SERVICE MANUAL

AUTORANGING
SYSTEM DC POWER SUPPLY
HP MODELS 6033A and 6038A

HP Part No. 5959-3346

FOR INSTRUMENTS WITH SERIAL NUMBERS

HP Model 6033A; Serials US38320231 and above

HP Model 6038A; Serials US38310401 and above

For instruments with higher serial numbers, a change page may be included.

Microfiche Part No. 5959-3347 Printed in USA: December, 1999

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 CERTIFICATION
Hewlett-Packard Company certifies that this product met its published specifications at time of shipment from the factory.
Hewlett-Packard further certifies that its calibration measurements are traceable to the United States National Bureau of
Standards, to the extent allowed by the Bureau’s calibration facility, and to the calibration facilities of other International
Standards Organization members.

WARRANTY
This Hewlett-Packard hardware product is warranted against defects in material and workmanship for a period of three years
from date of delivery. HP software and firmware products, which are designated by HP for use with a hardware product and
when properly installed on that hardware product, are warranted not to fail to execute their programming instructions due to
defects in material and workmanship for a period of 90 days from date of delivery. During the warranty period Hewlett-
Packard Company will, at its option, either repair or replace products which prove to be defective. HP does not warrant that
the operation of the software, firmware, or hardware shall be uninterrupted or error free.

For warranty service, with the exception of warranty options, this product must be returned to a service facility designated
by HP. Customer shall prepay shipping charges by (and shall pay all duty and taxes) for products returned to HP for
warranty service. Except for products returned to Customer from another country, HP shall pay for return of products to
Customer.

Warranty services outside the country of initial purchase are included in HP’s product price, only if Customer pays HP
international prices (defined as destination local currency price, or U.S. or Geneva Export price).

If HP is unable, within a reasonable time to repair or replace any product to condition as warranted, the Customer shall be
entitled to a refund of the purchase price upon return of the product to HP.

LIMITATION OF WARRANTY
The foregoing warranty shall not apply to defects resulting from improper or inadequate maintenance by the Customer,
Customer-supplied software or interfacing, unauthorized modification or misuse, operation outside of the environmental
specifications for the product, or improper site preparation and maintenance. NO OTHER WARRANTY IS EXPRESSED
OR IMPLIED. HP SPECIFICALLY DISCLAIMS THE IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS FOR A PARTICULAR PURPOSE.

EXCLUSIVE REMEDIES
THE REMEDIES PROVIDED HEREIN ARE THE CUSTOMER’S SOLE AND EXCLUSIVE REMEDIES. HP SHALL
NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES,
WHETHER BASED ON CONTRACT, TORT, OR ANY OTHER LEGAL THEORY.

ASSISTANCE
The above statements apply only to the standard product warranty. Warranty options, extended support contracts, product
maintenance agreements and customer assistance agreements are also available. Contact your nearest Hewlett-Packard
Sales and Service office for further information on HP’s full line of Support Programs.

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 SAFETY SUMMARY
The following general safety precautions must be observed during all phases of operation, service and repair of this
instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety
standards of design, manufacture, and intended use of the instrument. Hewlett-Packard Company assumes no liability for
the customer’s failure to comply with these requirements.

BEFORE APPLYING POWER.

Verify that the product is set to match the available line voltage and the correct fuse is installed.

GROUND THE INSTRUMENT.

This product is a Safety Class 1 instrument (provided with a protective earth terminal). To minimize shock hazard, the instrument chassis
and cabinet must be connected to an electrical ground. The instrument must be connected to the ac power supply mains through a three-
conductor power cable, with the third wire firmly connected to an electrical ground (safety ground) at the power outlet. For instruments
designed to be hard wired to the ac power lines (supply mains), connect the protective earth terminal to a protective conductor before any
other connection is made. Any interruption of the protective (grounding) conductor or disconnection of the protective earth terminal will
cause a potential shock hazard that could result in personal injury. If the instrument is to be energized via an external autotransformer for
voltage reduction, be certain that the autotransformer common terminal is connected to the neutral (earth pole) of the ac power lines
(supply mains).

FUSES
Only fuses with the required rated current, voltage, and specified type (normal blow, time delay, etc.) should be used. Do not use
repaired fuses or short circuited fuseholders. To do so could cause a shock or fire hazard.

DO NOT OPERATE IN AN EXPLOSIVE ATMOSPHERE.

Do not operate the instrument in the presence of flammable gases or fumes.

KEEP AWAY FROM LIVE CIRCUITS.

Operating personnel must not remove instrument covers. Component replacement and internal adjustments must be made by qualified
service personnel. Do not replace components with power cable connected. Under certain conditions, dangerous voltages may exist even
with the power cable removed. To avoid injuries, always disconnect power, discharge circuits and remove external voltage sources before
touching components.

DO NOT SERVICE OR ADJUST ALONE.

Do not attempt internal service or adjustment unless another person, capable of rendering first aid and resuscitation, is present.

DO NOT EXCEED INPUT RATINGS.

This instrument may be equipped with a line filter to reduce electromagnetic interference and must be connected to a properly grounded
receptacle to minimize electric shock hazard. Operation at the line voltage or frequencies in excess of those stated on the data plate may
cause leakage currents in excess of 5.0mA peak.

SAFETY SYMBOLS.
Instruction manual symbol: the product will be marked with this symbol when it is necessary for the user to refer to the
instruction manual (refer to Table of Contents) .

Indicates hazardous voltages.

Indicate earth (ground) terminal.

The WARNING sign denotes a hazard. It calls attention to a procedure, practice, or the like, which, if not correctly
performed or adhered to, could result in personal injury. Do not proceed beyond a WARNING sign until the
indicated conditions are fully understood and met.

The CAUTION sign denotes a hazard. It calls attention to an operating procedure, or the like, which, if not correctly
performed or adhered to, could result in damage to or destruction of part or all of the product. Do not proceed
beyond a CAUTION sign until the indicated conditions are fully understood and met.

DO NOT SUBSTITUTE PARTS OR MODIFY INSTRUMENT.

Because of the danger of introducing additional hazards, do not install substitute parts or perform any unauthorized modification to the
instrument. Return the instrument to a Hewlett-Packard Sales and Service Office for service and repair to ensure that safety features are
maintained.
Instruments which appear damaged or defective should be made inoperative and secured against unintended operation until they can be
repaired by qualified service personnel.

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 TABLE OF CONTENTS
Introduction ............................................................................................................................................................................ 9
Scope .................................................................................................................................................................................... 9
Calibration and Verification ............................................................................................................................................. 9
Troubleshooting................................................................................................................................................................ 9
Principles of Operation ..................................................................................................................................................... 9
Replaceable Parts.............................................................................................................................................................. 9
Circuit Diagrams............................................................................................................................................................... 9
Safety Considerations ........................................................................................................................................................... 9
Manual Revisions ............................................................................................................................................................... 10
Firmware Revisions ............................................................................................................................................................ 10
Calibration and Verification................................................................................................................................................ 11
Introduction ........................................................................................................................................................................ 11
Test Equipment Required ................................................................................................................................................... 11
Operation Verification Tests............................................................................................................................................... 11
Calibration Procedure ......................................................................................................................................................... 11
Initial Setup..................................................................................................................................................................... 14
Voltage Monitor Zero Calibration .................................................................................................................................. 15
Common Mode Calibration ............................................................................................................................................ 15
Remote Readback Zero Calibration................................................................................................................................ 16
Constant Voltage Full Scale Calibration......................................................................................................................... 16
Voltage Monitor and Remote Readback Full Scale Calibration ..................................................................................... 17
Constant Voltage Zero Calibration ................................................................................................................................. 17
Current Monitor Zero Calibration................................................................................................................................... 17
Constant Current Zero Calibration.................................................................................................................................. 18
Current Monitor Full Scale Calibration .......................................................................................................................... 18
Constant Current Full Scale Calibration ......................................................................................................................... 19
Power Limit Calibration ................................................................................................................................................. 19
Resistance Programming Full Scale Calibration............................................................................................................. 19
Performance Tests .............................................................................................................................................................. 20
Measurement Techniques ............................................................................................................................................... 20
Constant Voltage (CV) Tests.......................................................................................................................................... 21
Constant Current (CC) Tests........................................................................................................................................... 26
Initialization Procedure....................................................................................................................................................... 28
Troubleshooting .................................................................................................................................................................... 29
Introduction ........................................................................................................................................................................ 29
Initial Troubleshooting Procedures..................................................................................................................................... 29
Electrostatic Protection....................................................................................................................................................... 30
Repair and Replacement ..................................................................................................................................................... 30
A2 Control Board Removal ............................................................................................................................................ 31
A4 FET Board Removal ................................................................................................................................................. 31
A8 HP-IB Board Removal.............................................................................................................................................. 32
A3 Front-Panel Board Removal...................................................................................................................................... 32
A1 Main Board Removal................................................................................................................................................ 32
Overall Troubleshooting Procedure.................................................................................................................................... 33
HP-IB Section Troubleshooting.......................................................................................................................................... 33
Primary Interface Troubleshooting ..................................................................................................................................... 36
Secondary Interface Troubleshooting ................................................................................................................................. 38
Voltage and Current DAC .............................................................................................................................................. 38
Readback DAC Circuits.................................................................................................................................................. 39
Readback Multiplexer (U20): ......................................................................................................................................... 39

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 Signature Analysis .............................................................................................................................................................. 41
Primary SA ..................................................................................................................................................................... 41
Front Panel SA................................................................................................................................................................ 41
Secondary SA ................................................................................................................................................................. 42
Power Section Troubleshooting.......................................................................................................................................... 47
Main Troubleshooting Setup .......................................................................................................................................... 48
Troubleshooting No-Output Failures .............................................................................................................................. 49
Power Section Blocks ..................................................................................................................................................... 50
Troubleshooting AC-Turn-On Circuits........................................................................................................................... 53
Troubleshooting DC-To-DC Converter .......................................................................................................................... 53
Troubleshooting Bias Supplies ....................................................................................................................................... 54
Troubleshooting Down Programmer .............................................................................................................................. 57
Troubleshooting CV Circuit ........................................................................................................................................... 58
Troubleshooting CC Circuit............................................................................................................................................ 58
Troubleshooting OVP Circuit......................................................................................................................................... 59
Troubleshooting PWM & Clock..................................................................................................................................... 59
Principles of Operation ........................................................................................................................................................ 61
Introduction ........................................................................................................................................................................ 61
HP-IB Board....................................................................................................................................................................... 61
Primary Microprocessor ................................................................................................................................................. 61
Address Switches........................................................................................................................................................... 61
EEPROM........................................................................................................................................................................ 63
Isolation .......................................................................................................................................................................... 63
Secondary Microprocessor ............................................................................................................................................. 63
Digital-to-Analog Converters ......................................................................................................................................... 63
Analog Multiplexer......................................................................................................................................................... 63
Status Inputs ................................................................................................................................................................... 63
Front Panel Board............................................................................................................................................................... 64
Address Latches and Decoders ....................................................................................................................................... 64
Volts and Amps Output Ports and Displays.................................................................................................................... 64
RPG and Latches ............................................................................................................................................................ 64
Front-Panel Switches and Input Port .............................................................................................................................. 64
Mode Indicators.............................................................................................................................................................. 66
OVP Adjust Control ....................................................................................................................................................... 66
Power Clear .................................................................................................................................................................... 66
Power Mesh and Control Board.......................................................................................................................................... 66
Overview ........................................................................................................................................................................ 66
AC Turn-On Circuits ...................................................................................................................................................... 68
DC-to-DC Converter....................................................................................................................................................... 68
Down Programmer.......................................................................................................................................................... 69
Bleeder Circuit (6038A only) ......................................................................................................................................... 69
Constant-Voltage (CV) Circuit ....................................................................................................................................... 69
Constant-Current (CC) Circuit........................................................................................................................................ 70
Overvoltage Protection (OVP) Circuit............................................................................................................................ 70
Power-Limit Comparator ................................................................................................................................................ 70
Control-Voltage Comparator .......................................................................................................................................... 70
Initial-Ramp Circuit........................................................................................................................................................ 71
Pulse-Width Modulator (PWM) ..................................................................................................................................... 71
Bias Voltage Detector..................................................................................................................................................... 71
AC-Surge-&-Dropout Detector....................................................................................................................................... 71
1-Second-Delay Circuit .................................................................................................................................................. 72
Replaceable Parts ................................................................................................................................................................. 73
Introduction ........................................................................................................................................................................ 73

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 Ordering Information.......................................................................................................................................................... 74
Component Location and Circuit Diagrams ...................................................................................................................... 91

l00 Vac Input Power Option 100 ......................................................................................................................................... 99

General Information............................................................................................................................................................ 99
Description ..................................................................................................................................................................... 99
Scope of Appendix A...................................................................................................................................................... 99
Suggestions for Using Appendix A................................................................................................................................. 99
Chapter 1 Manual Changes............................................................................................................................................. 99
Chapter 2 Manual Changes............................................................................................................................................. 99
Chapter 3 Manual Changes:.......................................................................................................................................... 101
Chapter 4 Manual Changes:.......................................................................................................................................... 101
Chapter 5 and 6 Manual Changes ................................................................................................................................. 102
Blank Front Panel Option 001........................................................................................................................................... 103
Introduction ...................................................................................................................................................................... 103
Troubleshooting............................................................................................................................................................ 103
Chapter 2 Manual Changes:.......................................................................................................................................... 103
Chapter 3 Manual Changes:.......................................................................................................................................... 104
Chapter 5 and 6 Manual Changes: ................................................................................................................................ 104

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 1
Introduction

Scope

This manual contains information for troubleshooting the HP 6033A/6038A 200W Autoranging Power Supply to the
component level. Wherever applicable, the service instructions given in this manual refer to pertinent information provided
in the Operation Manual (P/N 5959-3301). Both manuals cover HP Models 6033A/6038A; differences between models are
described as required.

The following information is contained in this manual.

Calibration and Verification

Contains calibration procedures for HP Models 6033A/6038A. Also contains verification procedures that check the
operation of the supplies to ensure they meet the specifications of Chapter 1 in the Operating Manual.

Troubleshooting
Contains troubleshooting procedures to isolate a malfunction to a defective component on the main circuit board or to a
defective assembly (front panel, power transformer, or cable assembly). Board and assembly level removal and replacement
procedures are also given in this section.

Principles of Operation
Provides block diagram level descriptions of the supply’s circuits. The primary interface, secondary interface, and the power
mesh and control circuits are described. These descriptions are intended as an aid in troubleshooting.

Replaceable Parts
Provides a listing of replaceable parts for all electronic components and mechanical assemblies for HP Models
6033A/6038A.

Circuit Diagrams
Contains functional schematics and component location diagrams for all HP 6033A/6038A circuits. The names that appear
on the functional schematics also appear on the block diagrams in Chapter 2. Thus, the descriptions in Chapter 2 can be
correlated with both the block diagrams and the schematics.

Safety Considerations

This product is a Safety Class 1 instrument, which means that it is provided with a protective earth terminal. Refer to the
Safety Summary page at the beginning of this manual for a summary of general safety information. Safety information for
specific procedures is located at appropriate places in the manual.

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 Manual Revisions

Hewlett-Packard instruments are identified by a 10-digit serial number. The format is described as follows: first two letters
indicate the country of manufacture. The next four digits are a code that identify either the date of manufacture or of a
significant design change. The last four digits are a sequential number assigned to each instrument.

Item Description

US The first two letters indicates the country of manufacture, where US = USA.

3648 This is a code that identifies either the date of manufacture or the date of a significant design change.

0101 The last four digits are a unique number assigned to each power supply.

If the serial number prefix on your unit differs from that shown on the title page of this manual, a yellow Manual Change
sheet may be supplied with the manual. It defines the differences between your unit and the unit described in this manual.
The yellow change sheet may also contain information for correcting errors in the manual.

Note that because not all changes to the product require changes to the manual, there may be no update information required
for your version of the supply.

Older serial number formats used with these instruments had a two-part serial number, i.e. 2701A-00101. This manual also
applies to instruments with these older serial number formats. Refer to Appendix E for backdating information.

Firmware Revisions

The primary and secondary interface microcomputer chips inside of your supply are identified with labels that specify the
revision of the supply’s firmware. This manual applies to firmware revisions A.00.00, A.00.01, and A.00.02.

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 2
Calibration and Verification
Introduction

This section provides test and calibration procedures. The operation-verification tests comprise a short procedure to verify
that the unit is performing properly, without testing all specified parameters. After troubleshooting and repair of a defective
power supply you can usually verify proper operation with the turn-on checkout procedure in the Operating Manual. Repairs
to the A1 main board, the A2 control board and the A8 HP-IB board can involve circuits which, although functional, may
prevent the unit from performing within specified limits. So, after A1, A2 or A8 board repair, decide if recalibration and
operation verification tests are needed according to the faults you discover. Use the calibration procedure both to check
repairs and for regular maintenance.

Test Equipment Required

Table 2-1 lists the equipment required to perform the tests of this section. You can separately identify the equipment for
performance tests, calibration and troubleshooting using the USE column of the table.

Operation Verification Tests

To assure that the unit is performing properly, without testing all specified parameters, first perform the turn-on checkout
procedure in the Operating Manual. Then perform the following performance tests, in this section.

Voltage Programming And Readback Accuracy

Current Programming And Readback Accuracy
CV Load Effect
CC Load Effect

Calibration Procedure

Calibrate the unit twice per year and when required during repair. The following calibration procedures should be
performed in the sequence given.

Note: Some of the calibration procedures for this instrument can be performed independently, and some
procedures must be performed together and/or in a prescribed order. If a procedure contains no references
to other procedures, you may assume that it can be performed independently.

To return a serviced unit to specifications as quickly as possible with minimal calibration, the technician
need only perform calibration procedures that affect the repaired circuit. Table 2-2 lists various power
supply circuits with calibration procedures that should be performed after those circuits are serviced.

If the HP-IB board (A8) has been replaced, you must first initialize the board before you can calibrate the
unit. Refer to Page 28.

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 Table 2-1. Test Equipment Required

TYPE REQUIRED CHARACTERISTICS USE RECOMMENDED MODEL

Oscilloscope Sensitivity: 1 mV P,T HP54504A
Bandwidth: 20MHz & 100MHz
Input: differential, 50 Ω & 10MΩ
RMS Voltmeter True rms, 10MHz bandwidth P HP3400A
Sensitivity: 1 mV Accuracy: 5%
Logic Pulser 4.5 to 5.5Vdc @ 35mA T HP546A
Multimeter Resolution: 100nV P,C,T HP 3458A
Accuracy: 0.0035%, 6½ digit
Signature Analyzer -- T HP 5004A
HP-IB Controller Full HP-IB capabilities C,T,P HP Series, 200/300
Current Probe No saturation at 30Adc P Tektronix P6303 Probe/
Bandwidth: 20Hz to 20MHz AM503 Amp/
TM500 Power Module
Electronic Load Voltage range: 60Vdc P,C HP 6060A
Current range: 30Adc
Power range: 250W
Open and short switched
Power Resistor* Value: 0.25Ω >200W (6033A) P,C
Value: 2.3Ω >200W (6038A)
Current-Monitoring Value: 10mΩ ± 0.04% @ 100W (6033A) P,C** Guildline 9230/100
Shunts PC: 0.0004%/W
Value: 100mΩ ± 0.04% @ 25W (6038A) Guildline 9230/15
PC: 0.0004%/W
Calibration and Test Value: 100Ω, 5%, 1W C,T
Resistors 1Ω, 5%, ½W
1KΩ, 5%, ¼W
2KΩ, 0.01%, ¼W
Terminating Value: 50Ω ±5%, noninductive P
Resistors (2)
Blocking Value: 0.01µF, 100Vdc P
Capacitors (2)
Common-mode ≥3.7µH/turn2 P Ferrox-Cube
Toroidal Core ≅23mm I.D. 500T600-3C8,
HP 9170-0061
Switch* SPST, 30A @60V P
DC Power Supply Voltage range: 0-60Vdc C,T HP 6024A
Current range: 0-3Adc
P = performance testing C = calibration adjustments T = troubleshooting

* Not required if using electronic load.

** Less accurate, and less expensive, current-monitor resistors can be used, but the accuracy to which current programming
and readback can be checked must be reduced accordingly.

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 Table 2-2. Guide to Recalibration After Repair

Printed Circuit Block Name Ref. Perform These Procedures

Board Desig.

A1 Main Board R3 Current Monitor Full Scale Calibration

Constant Current Full Scale Calibration

A1 Main Board T1 Power Limit Calibration

A4 Power Mesh Board T3 Power Limit Calibration

A4 Power Mesh Board CR7 Power Limit Calibration

A2 Control Board Constant Voltage Circuit All Voltage Monitor Zero Calibration
(All Except Current Source) Common Mode Calibration
Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration

A2 Control Board Constant Voltage Circuit All Resistance Programming Full Scale Calibration
(Current Source)

A2 Control Board Constant Current Circuit All Current Monitor Zero Calibration
Constant Current Zero Calibration
Current Monitor Full Scale Calibration
Constant Current Full Scale Calibration

A2 Control Board Power Limit Comparator All Power Limit Calibration

A2 Control Board Bias Power Supplies All All Calibration Procedures

( + & -15V Supplies)

A8 HP-IB Board Voltage Monitor Buffer All Voltage Monitor Zero Calibration
Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration

A8 HP-IB Board Analog Multiplexer All Remote Readback Zero Calibration

Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration

A8 HP-IB Board Readback DAC All Remote Readback Zero Calibration

Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration

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 Table 2-2. Guide to Recalibration After Repair (continued)

Printed Circuit Block Name Ref. Perform These Procedures

Board Desig.
A8 HP-IB Board Voltage DAC All Remote Readback Zero Calibration
Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration

A8 HP-IB Board Current DAC All Constant Current Zero Calibration

Constant Current Full Scale Calibration

A8 HP-IB Board U5 Remote Readback Zero Calibration

Constant Voltage Full Scale Calibration
Voltage Monitor and Remote Readback Full
Scale Calibration
Constant Voltage Zero Calibration
Constant Current Full Scale Calibration

Initial Setup
a. Unplug the line cable and remove the top cover by removing the three screws; the rear handle screw and the two top-
rear-corner screws. Do not remove the front handle screw as the retaining nut will fall into the unit.
b. Slide the cover to the rear.
c. Plug a control board test connector A2J3 onto the A2J3 card-edge fingers.
d. Turn OVERVOLTAGE ADJUST control A3R59 fully clockwise.
e. Disconnect all loads from output terminals.
f. Connect power supply for local sensing, and ensure that MODE switches are set as shown below.

g. Connect an HP-IB controller to the power supply.

h. Reconnect line cable and turn on ac power.
i. Allow unit to warm up for 30 minutes.
j. When attaching the DVM, the minus lead of the DVM should be connected to the first node listed, and the plus lead
should be connected to the second node listed.
k. At the beginning of each calibration procedure, the power supply should be in its power-on state (turn ac power off and
back on), with no external circuitry connected except as instructed.
l. The POWER LIMIT adjustment (A2R25) must be adjusted at least coarsely before many of the calibration procedures
can be performed. If you have no reason to suspect that the Power Limit circuit is out of adjustment, do not change its
setting. Otherwise, center A2R25 before you begin to calibrate the power supply.
m. Turn off ac power when making or removing connections to the power supply.

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 Maintenance described herein is performed with power supplied to the instrument, and protective covers
removed. Such maintenance should be performed only by trained service personnel who are aware of the
hazards involved (for example, fire and electrical shock). Where maintenance can be performed without
power applied, the power should be removed.

Voltage Monitor Zero Calibration

a. Send string "VSET 0; ISET 0; OUT OFF".

b. Short power supply output terminals.
c. Attach the DVM from M on the rear panel through a 1kΩ resistor to A2P3 pin 3 (V-MON1).
d. Adjust A2R22 (V-MON ZERO) to 0V ±20µV.

Common Mode Calibration

a. Send string ’’VSET 0; ISET 0; OUT OFF".

b. Short power supply sense terminals ( + S to - S) at rear panel.
c. Attach the DVM from M on the rear panel through a 1kΩ resistor to A2J3 pin 3 (V-MON).
d. Take initial reading from DVM.
e. Remove both local sensing straps from rear-panel terminal block, and connect a 1-volt external power supply with its +
lead to - S and its--lead to - Out. See Figure 2-1.
Adjust A2R21 (CV LOAD REG) to Initial Reading ±20µV.
f. Replace local sense straps after removing external power supply.

Figure 2-1. Common Mode Setup

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 Remote Readback Zero Calibration

Note: This procedure and the following three procedures must be done as a set, without omitting any of the four
procedures. Also, the following four procedures require that V-MON ZERO (A2R22) be adjusted within
specifications. If it is not, perform the Voltage Monitor Zero Calibration before proceeding.

a. Connect an external supply to the power supply as shown in Figure 2-2.

b. Send string "VSET 0; ISET 5; OUT ON’’.
c. Attach the DVM from M on the rear panel through a 1KΩ resistor to A2J3 pin 3 (V-MON).
d. Adjust A8R40 (CV PROG ZERO) to 625µV ± 30µV.
e. Remove the DVM.
f. Enter and run the following program and begin noting the controller’s display:
10 OUTPUT 705; "VOUT’’
20 ENTER 705; A
30 DISP A
40 GOTO 10
50 END
g. Adjust A8R51 (READBACK ZERO) until the value displayed on the controller toggles between:
0 and 5mV (6033A).
0 and 15mV (6038A).
h. After adjusting A8R51 you must continue the calibration procedure through to the completion of Constant Voltage
Zero Calibration. Remember to disconnect the external power supply and resistor.

Figure 2-2. Remote Readback Zero And CV Zero Calibration Setup

Constant Voltage Full Scale Calibration

Note: Perform this procedure only after completing Remote Readback Zero Calibration.

a. Remove all external test circuits.

b. Send string:
"VSET 200; ISET 5; OUT ON" (6033A).
"VSET 60; ISET 5; OUT ON" (6038A).

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 c. Attach the DVM from - S to + S terminals on rear panel.
d. Adjust A8R58 (CV PROG F.S.) to:
20.0025 ±600µV (6033A).
60.0075 ±1.82mV (6038A).
e. After adjusting A8R58 you must continue the calibration procedure through to the completion of Constant Voltage
Zero Calibration.

Voltage Monitor and Remote Readback Full Scale Calibration

Note: Perform this procedure only after completing Constant Voltage Full Scale Calibration.

a. Attach the DVM from M on the rear panel to A2J3 pin 3 (V-MON). See DVM connection in Figure 2-1.
b. Send string: ’’VSET 20; ISET 5; OUT ON’’ (6033A).
’’VSET 60; ISET 5; OUT ON’’ (6038A).
c. Adjust A8R75 (V-MON F.S.) to 5.000625V ±100µV.
d. Disconnect the DVM.
e. Enter and run the following program and begin noting the controller’s display.
10 OUTPUT 705; ’’VOUT?’’
20 ENTER 705; A
30 DISP A
40 GOTO 10
50 END
f. Adjust A8R61 (READBACK F.S.) until the value displayed on the controller toggles between:
20V and 20.005V (6033A).
60V and 60.015V (6038A).
g. After adjusting A8R61 you must continue the calibration procedure through to the completion of Constant Voltage
Zero Calibration.

Constant Voltage Zero Calibration

Note: Perform this procedure only after completing Voltage Monitor and Remote Readback Full Scale
Calibration.

a. Send string "VSET 0; ISET 5; OUT ON".

b. Connect an external supply to the power supply as shown in Figure 2-2.
c. Attach the DVM from - S to + S on the rear panel.
d. Adjust A8R40 (CV PROG ZERO) to 0 ±120µV.

Current Monitor Zero Calibration

a. Send string "VSET 0; ISET 0; OUT OFF’’.

b. Connect a short across power supply output terminals.
c. Attach the DVM from M to IM on the rear panel.
d. Allow several minutes (3 or more) to ensure thermal settling.
e. Adjust A2R8 (I-MON ZERO) to:
0V ±100µV (6033A).
0V ±25µV (6038A).

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 Constant Current Zero Calibration

a. Connect the test setup shown in Figure 2-3.

b. Send string ’’VSET 5; ISET 0; OUT ON’’.
c. Allow several minutes (3 or more) to ensure thermal settling.
d. Adjust A8R29 (CC PROG ZERO) to:
0V ±1mV (6033A).
0V ±350µV (6038A).

Figure 2-3. CC Zero Calibration Setup

Current Monitor Full Scale Calibration

Note: This procedure requires that I-MON ZERO (A2R8) be adjusted within specifications. If it is not, perform
the Current Monitor Zero Calibration before proceeding.

a. Connect Rm current-monitoring shunt:

(10 milliohm, 6033A)
(100 milliohm, 6038A)
0.05% or better across power supply output terminals.
b. Send string:
"VSET 5; ISET 30; OUT ON" (6033A).
"VSET 5; ISET 10; OUT ON" (6038A).
c. Attach DVM from M to IM on the rear panel. Use six-digit display on HP 3458A DVM.
d. Take initial reading from DVM.
e. Attach DVM across Rm. Allow several minutes (3 or more) to ensure thermal settling. This can be noted as a stable
reading on the DVM.
f. Adjust A2R9 (I-MON F.S.) to:
0.060 x initial reading ±0.4mV (6033A).
0.200 x initial reading ±1.0mV (6038A).

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 Constant Current Full Scale Calibration

Note: This procedure requires that CC PROG ZERO (A8R29) and I-MON F. S. (A2R9) be adjusted within
specifications. If they are not, perform Constant Current Zero and/or Current Monitor Full Scale
Calibration before proceeding.

a. Connect Rm current-monitoring shunt:

(10 milliohm, 6033A)
(100 milliohm, 6038A)
0.05% or better across power supply output terminals.
b. Send string:
"VSET 5; ISET 30; OUT ON" (6033A).
"VSET 5, ISET 10; OUT ON’’ (6038A).
c. Attach DVM across Rm. Allow several minutes (3 or more) to ensure thermal settling.
d. Adjust A8R55 (CC PROG F.S.) to:
300mV ±30µV (6033A).
100mV ±100µV (6038A).

Power Limit Calibration

Note: This procedure requires that CC PROG F. S. (A8R55) be adjusted within specifications. If it is not,
perform Constant Current Full Scale Calibration before proceeding.

a. Connect the power supply to the ac power line through a variable autotransformer which is set to the minimum for your
line voltage (e.g. 104V for nominal 120V line).
b. Turn A2R25 (POWER LIMIT) fully counterclockwise.
c. Connect a electronic load across the output terminals, or use a:
0.25Ω 200W resistor (6033A).
2.3Ω 200W resistor (6038A).
d. Set the electronic load for:
30 amperes (6033A).
10 amperes (6038A).
in the constant Current mode.
e. Turn on power supply and send string:
"VSET 9; ISET 30.5; OUT ON" (6033A).
’’VSET 23; ISET 10.2; OUT ON’’ (6038A).
f. Adjust A2R25 (POWER LIMIT) clockwise until CV LED on front panel turns on.

Resistance Programming Full Scale Calibration

a. Send string ’’OUT OFF".

b. Connect a 2-kilohm calibration resistor from P to VP on rear panel.
c. Set rear-panel MODE switches for resistance programming:

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 d. Attach the DVM from P to VP on the rear panel.
e. Adjust A2R23 (R-PROG F.S.) to 2.5V ±4mV.
f. Remember to reset MODE switches to original settings.

Performance Tests

The following paragraphs provide test procedures for verifying the unit’s compliance with the specifications of Table 1-1 in
the Operating Manual. Please refer to CALIBRATION PROCEDURE or TROUBLESHOOTING if you observe
out-of-specification performance. The performance test specifications are listed in the Performance Test Record in
Appendix C and D. You can record the actual measured values in the columns provided.

Measurement Techniques

Setup For All Tests. Measure the output voltage directly at the + S and - S terminals. Connect unit for local sensing, and
ensure that MODE switches are set as shown below. Select an adequate wire gauge for load leads using the procedures
given in the Operating Manual for connecting the load.

Electronic Load. The test and calibration procedures use an electronic load to test the unit quickly and accurately. If an
electronic load is not available, you may substitute:
2Ω 200W load resistor (6033A).
18Ω 200W load resistor (6038A).
for the electronic load in these tests:
CV Source Effect (Line Regulation).
CC Load Effect (Load Regulation).

You may substitute:

0.25Ω 200W load resistor (6033A).
2.3Ω 200W load resistor (6038A).
in these tests:
CV Load Effect (Load Regulation)
CV PARD (Ripple and Noise)
CC Source Effect (Line Regulation)
CC PARD (Ripple and Noise)

The substitution of the load resistor requires adding a load switch and making minor changes to the procedures. The load
transient recovery time test procedure is not amenable to modification for use with load resistors.

An electronic load is considerably easier to use than a load resistor. It eliminates the need for connecting resistors or
rheostats in parallel to handle the power, it is much more stable than a carbon-pile load, and it makes easy work of switching
between load conditions as is required for the load regulation and load transient-response tests.

Current-Monitoring Resistor. To eliminate output current measurement error caused by voltage drops in the leads and
connections, connect the current-monitoring resistor between -OUT and the load as a four-terminal device. Figure 2-4
shows correct connections. Connect the current-monitoring test leads inside the load-lead connections directly at the
monitoring resistor element.

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 Note: A current-monitoring resistor with 1% accuracy is suitable for all tests except current programming
accuracy and current readback accuracy. For these tests, use the shunt listed in Table 2-1.

Figure 2-4. Current-Monitoring Resistor Setup

HP-IB Controller. Most performance tests can be performed using only front-panel controls. However, an HP-IB
controller is required to perform the voltage and current programming accuracy tests and the voltage and current readback
accuracy tests.

Constant Voltage (CV) Tests

CV Setup. If more than one meter or a meter and an oscilloscope are used, connect each to the + S and - S terminals by a
separate pair of leads to avoid mutual coupling effects. Connect only to + S and -S because the unit regulates the output
voltage between + S and - S, not between + OUT and -OUT. Use coaxial cable or shielded 2-wire cable to avoid pickup on
test leads. For all CV tests set the output current at full output to assure CV operation.

Voltage Programming And Readback Accuracy. This procedure verifies that the voltage programming and readback
functions are within specifications. An HP-IB controller must be used for this test.
a. Connect digital voltmeter between + S and - S.
b. Turn on ac power to the power supply.
c. Send string:
’’VSET 0.1; ISET 30’’ (6033A).
’’VSET 0.09; ISET 10" (6038A).
d. The DVM reading should be in the range:
0.090 to 0.109Vdc (6033A).
0.050 to 0.130Vdc (6038A).
Note the reading.
e. Enter and run the following program:
10 OUTPUT 705; "VOUT?"
20 ENTER 705;A
30 DISP A
40 GOTO 10
50 END
f. The value displayed by the controller should be the value noted in step d:
± 0.006Vdc (6033A).
± 0.015Vdc (6038A).
g. Send string:
"VSET 20; ISET 30" (6033A).
’’VSET 60; ISET 10" (6038A).
h. The DVM reading should be in the range:
19.984 to 20.016Vdc (6033A).
59.939 to 60.061Vdc (6038A).
Note the reading.

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 i. Run the program listed in step e. The value displayed by the controller should be the value noted in step h:
± 0.02Vdc (6033A).
± 0.092Vdc (6038A).

Load Effect (Load Regulation). Constant-voltage load effect is the change in dc output voltage (Eo) resulting from a
load-resistance change from open-circuit to full-load. Full-load is the resistance which draws the maximum rated output
current at voltage Eo. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit’s power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
c. Turn up output voltage to:
7.0Vdc (6033A).
20.0Vdc (6038A).
as read on the digital voltmeter.

Figure 2-5. Basic Test Setup

d. Reduce the resistance of the load to draw an output current of:

29Adc (6033A).
10 Adc (6038A).
Check that the unit’s CV LED remains lighted.
e. Open-circuit the load.
f. Record the output voltage at the digital voltmeter.
g. Reconnect the load.
h. When the reading settles, record the output voltage again. Check that the two recorded readings differ no more than:
± 0.0027Vdc (6033A).
± 0.005Vdc (6038A).

Source Effect (Line Regulation). Source effect is the change in dc output voltage resulting from a change in ac input
voltage from the minimum to the maximum value as specified in Input Power Requirements in the Specifications Table, in
the Operating Manual. Proceed as follows:

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 a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Connect the unit to the ac power line through a variable autotransformer which is set for nominal line voltage.
c. Turn the unit’s power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.

d. Turn up output voltage to:

20.0Vdc (6033A).
60.0Vdc (6038A).
as read on the digital voltmeter.
e. Reduce the resistance of the load to draw an output current of:
10Adc (6033A).
3.3Adc (6038A).
Check that the unit’s CV LED remains lighted.
f. Adjust autotransformer to the minimum for your line voltage.
g. Record the output voltage at the digital voltmeter.
h. Adjust autotransformer to the maximum for your line voltage.
i. When the reading settles record the output voltage again. Check that the two recorded readings differ no more than:
± 0.003Vdc (6033A).
± 0.008Vdc (6038A).

PARD (Ripple And Noise). Periodic and random deviations (PARD) in the unit’s output-ripple and noise-combine to
produce a residual ac voltage superimposed on the dc output voltage. Constant-voltage PARD is specified as the
root-mean-square (rms) or peak-to-peak (pp) output voltage in a frequency range of 20Hz to 20MHz.

RMS Measurement Procedure. Figure 2-6 shows the interconnections of equipment to measure PARD in Vrms. To ensure
that there is no voltage difference between the voltmeter’s case and the unit’s case, connect both to the same ac power outlet
or check that the two ac power outlets used have the same earth-ground connection.

Use the common-mode choke as shown to reduce ground-loop currents from interfering with measurement. Reduce noise
pickup on the test leads by using 50Ω coaxial cable, and wind it five turns through the magnetic core to form the
common-mode choke. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-6. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit’s power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
c. Turn up output voltage to:
7Vdc (6033A).
20Vdc (6038A).
d. Reduce the resistance of the load to draw an output current of:
29Adc (6033A).
10Adc (6038A).
Check that the unit’s CV LED remains lighted.
e. Check that the rms noise voltage at the true rms voltmeter is no more than 30mV rms.

Peak-To-Peak Measurement Procedure. Figure 2-7 shows the interconnections of equipment to measure PARD in Vpp.
The equipment grounding and power connection instructions on Page 23 apply to this setup also. Connect the oscilloscope
to the + S and - S terminals through 0.01µF blocking capacitors to protect the oscilloscope’s input from the unit’s output
voltage. To reduce common-mode noise pickup, set up the oscilloscope for a differential, two-channel voltage measurement.
To reduce normal-mode noise pickup, use matched-length, 1 meter or shorter, 50Ω coaxial cables with shields connected to
the oscilloscope case and to each other at the other ends. Proceed as follows:

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 Figure 2-6. RMS Measurement Test Setup, CV PARD Test

Figure 2-7. Peak-To-Peak Measurement Test Setup, CV PARD Test

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 a. Connect the test equipment as shown in Figure 2-7. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to maximum.
b. Turn the unit’s power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
c. Turn up output voltage to:
7Vdc (6033A).
20Vdc (6038A).
d. Turn up output current setting to full output and reduce the resistance of the load to draw an output current of:
29Adc (6033A).
10Adc (6038A).
Check that the unit’s CV LED remains lighted.
e. Set the oscilloscope’s input impedance to 50Ω and bandwidth to 20MHz. Check that the peak-to-peak is no more than
30mV.

Load Transient Recovery Time. Specified for CV operation only; load transient recovery time is the time for the output
voltage to return to within a specified band around its set voltage following a step change in load.

Use the equipment setup of Figure 2-5 to display output voltage transients while switching the load between 10% with the
output set at:
6.7Vdc (6033A).
20Vdc (6038A).

Proceed as follows:

a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant-current mode and set for minimum
current.
b. Turn the unit’s power on, and, using DISPLAY SETTINGS pushbutton switch, turn up current setting to full output.
c. Turn up output voltage to:
6.7Vdc (6033A).
20.0Vdc (6038A).
as read on the digital voltmeter.
d. Set the load to vary the load current between:
27Adc and 30Adc (6033A).
9Adc and 10 Adc (6038A).
at a 30Hz rate for the 10% RECOVERY TEST.
e. Set the oscilloscope for ac coupling, internal sync and lock on either the positive or negative load transient.
f. Adjust the oscilloscope to display transients as in Figure 2-8.
g. Check that the amplitude of the transient pulse at 1 ms is no more than:
50mV (6033A).
75mV (6038A).

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 .
Figure 2-8. Load Transient Recovery Waveform

Constant Current (CC) Tests

CC Setup. Constant-current tests are analogous to constant-voltage tests, with the unit’s output short circuited and the
voltage set to full output to assure CC operation. Follow the general setup instructions of Page 20.

Current Programming And Readback Accuracy. This procedure verifies that the current programming and readback
functions are within specifications. An HP-IB controller must be used for this test. The accuracy of the current shunt resistor
(Rm) must be 0.02% or better. Proceed as follows:

a. Connect test setup shown in Figure 2-5, except replace the load with a short circuit.
b. Turn on ac power to the power supply.
c. Send string:
"VSET 20; ISET 1.0" (6033A).
’’VSET 60; ISET 0.5" (6038A).
d. Check that the voltage across Rm is in the range:
9.79mV to 10.22mV (6033A).
48.9mV to 51.0mV (6038A).
Note the reading.
e. Enter and run the following program:
10 OUTPUT 705; "IOUT?’’
20 ENTER 705; A
30 DISP A
40 GOTO 10
50 END
f. The value displayed by the controller should be the actual output current ± 0.025Adc.
g. Send string:
’’VSET 20; ISET 30" (6033A).
’’VSET 60; ISET 10" (6038A).
h. Check that the voltage across Rm is in the range:
0.29935 to 0.30065Vdc (6033A).
1.0019 to 0.9982Vdc (6038A).
Note the reading.
i. Run the program listed in step e.
j. The value displayed by the controller should be the actual output current:
± 0.115Adc (6033A).
± 0.031Adc (6038A).

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 Load Effect (Load Regulation). Constant current load effect is the change in dc output current (Io) resulting from a
load-resistance change from short-circuit to full-load, or full-load to short-circuit. Full-load is the resistance which develops
the maximum rated output voltage at current Io. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
b. Turn the unit’s power on, and, using DISPLAY SETTINGS pushbutton switch, turn up voltage setting to full output.
c. Turn up output current to:
10Adc (6033A).
3Adc (6038A).
d. Increase the load resistance until the output voltage at +S and -S decreases to:
20Vdc (6033A).
60Vdc (6038A).
Check that the CC LED is lighted and AMPS display still reads ≈ 10 amps.
e. Short-circuit the load and allow the voltage across Rm to stabilize.
f. Record voltage across Rm.
g. Disconnect short across load.
h. When the reading settles (≈ 10s), record the voltage across Rm again. Check that the two recorded readings differ no
more than:
± 100µVdc (6033A).
± 530µVdc (6038A).

Source Effect (Line Regulation). Constant current source effect is the change in dc output current resulting from a change
in ac input voltage from the minimum to the maximum values listed in the Specifications Table in the Operating Manual.
Proceed as follows:
a. Connect the test equipment as shown in Figure 2-5. Operate the load in constant resistance mode (Amps/Volt) and set
resistance to minimum.
b. Connect the unit to the ac power line through a variable autotransformer set for nominal line voltage.
c. Switch the unit’s power on and turn up output voltage setting to full output.
d. Turn up output current to:
30Adc (6033A).
10Adc (6038A).
e. Increase the load resistance until the output voltage between + S and - S decreases to:
7.0Vdc (6033A).
20.0Vdc (6038A).
Check that the CC LED is still on.
f. Adjust autotransformer to the minimum for your line voltage.
g. Record the voltage across Rm.
h. Adjust autotransformer to the maximum for your line voltage.
i. When the reading settles record the voltage across Rm again. Check that the two recorded readings differ no more than:
90µVdc (6033A).
300µVdc (6038A).

PARD Ripple And Noise. Periodic and random deviations (PARD) in the unit’s output (ripple and noise) combine to
produce a residual ac current as well as an ac voltage super-imposed on the dc output. The ac voltage is measured as
constant-voltage PARD, Page 23. Constant-current PARD is specified as the root-mean-square (rms) output current in a
frequency range 20Hz to 20MHz with the unit in CC operation. To avoid incorrect measurements, with the unit in CC
operation, caused by the impedance of the electronic load at noise frequencies, use a:
0.25Ω (6033A)
2.3Ω (6038A)
load resistor that is capable of safely dissipating 200 watts. Proceed as follows:
a. Connect the test equipment as shown in Figure 2-9.
b. Switch the unit’s power on and turn the output voltage all the way up.
c. Turn up output current to:

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 29Adc (6033A).
10Adc (6038A).
Check that the unit’s CC LED remains lighted.
d. Check that the rms noise current measured by the current probe and rms voltmeter is no more than:
15mA rms (6033A).
5mA rms (6038A).

Initialization Procedure

Follow the procedure if either the HP-IB assembly has been replaced, or the EEPROM (U70) has been replaced:
1. Install the HP-IB assembly in the unit.
2. Turn the power on and depending on your unit’s model number, send string:
"EEINIT 6033"
or
"EEINIT 6038’’.
3. Turn the power off, wait 5 seconds, then turn the power back on.
4. If the HP-IB assembly has been replaced, calibrate the unit.

Figure 2-9. CC PARD Test Setup

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 3
Troubleshooting
Maintenance described herein is performed with power supplied to the instrument, and protective covers
removed. Such maintenance should be performed only by service-trained personnel who are aware of the
hazards involved (for example, fire and electrical shock). Where maintenance can be performed without
power applied, the power should be removed.

Introduction

Before attempting to troubleshoot this instrument, ensure that the fault is with the instrument itself and not with an
associated circuit. The performance test enables this to be determined without having to remove the covers from the supply.

The most important aspect of troubleshooting is the formulation of a logical approach to locating the source of trouble. A
good understanding of the principles of operation is particularly helpful, and it is recommended that Chapter 4 of this
manual be reviewed before attempting to troubleshoot the unit. Often the user will then be able to isolate a problem simply
by using the operating controls and indicators. Once the principles of operation are understood, refer to the following
paragraphs.

Table 2-1 lists the test equipment for troubleshooting. Chapter 6 contains schematic diagrams and information concerning
the voltage levels and waveforms at many of the important test points. Most of the test points used for troubleshooting the
supply are located on the control board test "fingers", which are accessible close to the top of the board. See Table 3-9.

If a component is found to be defective, replace it and re-conduct the performance test. When a component is replaced, refer
to Calibration Procedure (Chapter 2). It may be necessary to perform one or more of the adjustment procedures after a
component is replaced.

Initial Troubleshooting Procedures

If a problem occurs, follow the steps below in sequence:

a. Check that input power is available, and check the power cord and rear-panel line fuse.
b. Check that the settings of mode switch A2S1 are correct for the desired mode of operation. (See Operating Manual).
c. Check that all connections to the power supply are secure and that circuits between the supply and external devices are
not interrupted.
d. Check that the rear-panel HP-IB address switch A8S1 is properly set. (See Operating Manual).
e. If the power supply fails turn-on self-test or gives any other indication of malfunction, remove the unit from the
operating system before proceeding with further testing.

Some circuits on the power mesh are connected directly to the ac power line. Exercise extreme caution
when working on energized circuits. Energize the supply through an isolation transformer to avoid
shorting ac energized circuits through the test instrument’s input leads. The isolation transformer must
have a power rating of at least 4KVA. During work on energized circuits, the safest practice is to
disconnect power, make or change the test connections, and then re-apply power.

Make certain that the supply’s ground terminal ( ) is securely connected to an earth ground before applying
power. Failure to do so will cause a potential shock hazard that could result in personal injury.

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 Electrostatic Protection

The following caution outlines important precautions which should be observed when working with static sensitive
components in the power supply.

This instrument uses components which can be damaged by static charge. Most semiconductors can
suffer serious performance degradation as a result of static charges, even though complete failure may
not occur. The following precautions should be observed when handling static-sensitive devices.

a. Always turn power off before removing or installing printed-circuit boards.

b. Always store or transport static-sensitive devices (all semiconductors and thin-film devices) in conductive material.
Attach warning labels to the container or bag enclosing the device.
c. Handle static-sensitive devices only at static-free work stations. These work stations should include special conductive
work surfaces (such as HP Part No. 9300-0797) grounded through a one-megohm resistor. Note that metal table tops
and highly conductive carbon-impregnated plastic surfaces are too conductive; they can act as large capacitors and
shunt charges too quickly. The work surfaces should have distributed resistance of between 106and 10l2 Ω per square.
d. Ground all conductive equipment or devices that may come in contact with static-sensitive devices or sub-assemblies
containing same.
e. Where direct grounding of objects in the work area is impractical, a static neutralizer should be used (ionized air blower
directed at work). Note that this method is considerably less effective than direct grounding and provides less protection
for static-sensitive devices.
f. While working with equipment on which no point exceeds 500 volts, use a conductive wrist strap in contact with skin.
The wrist strap should be connected to ground through a one-megohm resistor. A wrist strap with insulated cord and
built-in resistor is recommended, such as 3M Co. No. 1066 (HP Part No. 9300-0969 (small) and 9300-0970 [large]).

Do not wear a conductive wrist strap when working with potentials in excess of 500 volts; the one-megohm
resistor will provide insufficient current limiting for personal safety.

g. All grounding (device being repaired, test equipment, soldering iron, work surface, wrist strap, etc.) should be done to
the same point.
h. Do not wear nylon clothing. Keep clothing of any kind from coming within 12 inches of static-sensitive devices.
i. Low-impedance test equipment (signal generators, logic pulsers, etc.) should be connected to static-sensitive inputs
only while the components are powered.
j. Use a mildly activated rosin core solder (such as Alpha Metal Reliacor No. 1, HP Part No. 8090-0098) for repair. The
flux residue of this type of solder can be left on the printed circuit board. Generally, it is safer not to clean the
printed-circuit board after repair. Do not use Freon or other types of spray cleaners. If necessary, the printed-circuit
board can be brushed using a natural-bristle brush only. Do not use nylon-bristle or other synthetic-bristle brushes. Do
not use high-velocity air blowers (unless ionized).
k. Keep the work area free of non-conductive objects such as Styrofoam-type cups, polystyrene foam, polyethylene bags,
and plastic wrappers. Non-conductive devices that are necessary in the area can be kept from building up a static charge
by spraying them with an anti-static chemical (HP Part No. 8500-3397).
l. Do not allow long hair to come in contact with static-sensitive assemblies.
m. Do not exceed the maximum rated voltages specified for the device.

Repair and Replacement

Repair and replacement of most components in the power supply require only standard techniques that should be apparent to
the technician. The following paragraphs provide instructions for removing certain assemblies and components for which
the procedure may not be obvious upon inspection.

To avoid the possibility of personal injury, remove the power supply from operation before opening the
cabinet. Turn off ac power and disconnect the line cord, HP-IB plug, load, and remote sense leads before

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 attempting any repair or replacement.

When replacing any heatsink-mounted components except thermostat, smear a thin coating of heatsink
compound between the component and heatsink. If a mica insulator is used, smear a thin coating of
heatsink compound on both sides of the mica insulator.

Do not use any heatsink compound containing silicone, which can migrate and foul electrical contacts
elsewhere in the system. An organic zinc oxide cream, such as American Oil and Supply Company
Heatsink Compound #100, is recommended.

Most of thc attaching hardware in this unit is metric. The only non-metric (sometimes called English or
inch) fittings are listed below. Be careful when both types of screws are removed not to get them mixed
up.

a. Rear-panel fuseholder.
b. Rear-panel ground binding post.

Top Outside Cover Removal. Remove one screw - the rear handle screw using a Size 2, Pozidriv screwdriver. A Phillips
head screwdriver does not fully seat into Pozidriv screws and risks stripping the heads. (Do not remove the front handle
screw, as the retaining nut will fall into the unit.) Remove the top cover by sliding it to the rear and lifting at the front.

Bottom Cover Removal. Remove only for repair of main board. Remove two bottom-rear-corner screws (Pozidriv,
M4x.7), and remove the bottom cover by sliding it to the rear. You do not need to remove the unit’s feet.

Inside Top Cover Removal. The unit includes an inside cover which secures the vertical board assemblies. Remove the
inside cover for repair but not for calibration.

Remove the six mounting screws (Pozidriv, M4x.7) - three on each side - and the five board-fastening screws (Pozidriv,
M4x.17) - all on top. Remove the inside cover by lifting at the front edge.

When installing the inside cover, insert it first at the right side. While holding it tilted up at the left, reach through the
cutouts in the cover and fit the top tabs of the A8 HP-IB board into the mating slots in the cover. Then repeat the process for
the A2 control board tabs and slots. With the top cover in place reach through the cutout above the A3 power mesh board,
align the board-fastening screw holes, and replace the rear-most screw to secure the A3 board. Press the inside cover down
firmly while tightening screws that secure cover to chassis. Complete the installation by replacing the remaining ten screws.

A2 Control Board Removal

After removing the inside cover, unplug the W5 and W6 ribbon cables at the top edge of the A2 control board. Remove the
A2 board by lifting first at the front edge and than pulling it up and out of the unit. Two connectors hold the A2 board at its
bottom edge.

When installing the A2 board, insert it first at the rear of the unit. While holding it tilted up at the front, fit the A2TB1
terminal strip into the mating cutout in the rear panel. Then lower the A2 board’s bottom connectors into the mating
connectors on the main board. Press the A2 board into the connectors, and reinstall the W5 and W6 ribbon cables.

A4 FET Board Removal

After removing the inside cover, remove the A4 mesh board by lifting, using the large aluminum heatsink as a handle. Two
connectors hold the A4 board at its bottom edge.

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 When installing the A4 power mesh board, lower it into its connectors and press in place.

A8 HP-IB Board Removal

Remove the A8 board as follows:

a. Remove the two screws (Pozidriv, M3x.5) which attach the A8 HP-IB board to the rear panel. Remove the single screw
(Pozidriv, M4x.7) that secures the HP-IB board to the side frame near the front corner.
b. After removing the inside cover, unplug the W5 and W6 ribbon cables at the top edge of the A8 board, the W2 3-wire
cable from connector A8J10 and the W1 ribbon cable from connector A8J9.
c. Remove the A8 board lifting it straight up.

Install the A8 board by reversing the above steps. Lower the rear side of the board into the unit first and fit the bottom tabs
into their mating slots.

A3 Front-Panel Board Removal

Remove the A3 front-panel board by first removing the entire front panel assembly. You do not need to remove the top
cover. Follow this procedure:
a. Remove the top plastic insert by prying up with a flat-blade screwdriver.
b. Remove the four front-panel assembly mounting screws on the top and bottom at the corners.
c. Gently pull the front-panel assembly away from the unit as far as permitted by the connecting cables.
d. Remove the ground-wire screw (Pozidriv, M4x.7) holding the green-yellow ground wire.
e. Note the locations of the four power-wire connections to the power switch and then unplug the quick-connect plugs.
f. Unplug the W3 3-wire cable from connector A1J3 to the A1 main board, and unplug the W1 ribbon cable from
connector A8J1 on the A8 HP-IB board.
g. Remove the A3 board from the front-panel assembly by removing the five mounting screws (Pozidriv, M4x.7).

Install the A3 Board by reversing the above steps. Connect the power switch wires in the exact locations from which they
were removed.

A1 Main Board Removal

Removing the A1 main board requires removing the rear-panel, all boards except the A3 front-panel board, and 17 A1
board mounting screws, two standoffs, and and interface bracket. Component-access cutouts in the bottom inside cover
allow unsoldering most A1-board components for repair without removing the A1 board.
Proceed as follows:

a. Remove the A2, A4, and A8 boards according to the above instructions.
b. Detach the rear panel by removing the four mounting screws (Pozidriv, M4x.7)-two on each side. Gently pull the rear
panel away from the unit as far as permitted by the four wires connected to the A1 board.
c. Remove the A8 bracket by removing three screws (Pozidriv, M4x.7) - two on bracket, one on side of the unit.
d. Unplug the W2 3-wire ribbon cable from connector A1J2, and unplug the W3 3-wire cable from connector A1J3.
e. Remove the A1 board by removing the 17 mounting screws (Pozidriv, M4x.7).
f. Note locations and then unplug the two ac power wires and the two fan wires to the A1 board.
Install the A1 board by reversing the above steps. Plug the two ac-power wires onto the two spade terminals in the left-rear
corner of the A1 board. Use the table below to choose the correct terminal for each wire.

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 AC POWER WIRE PLUG ONTO TERMINAL
from color desig. located
F1 fuse wht/brn/gry L left-rear corner
FL1 line module white/gry N right of above

Plug the fan wires, ignoring color codes if any, onto the remaining pair of terminals.

Overall Troubleshooting Procedure

The overall troubleshooting procedure for the unit involves isolating the problem to one of several circuit blocks and
troubleshooting the block individually. The HP-IB/ microprocessor related circuit blocks are located on the A3 (front panel)
and the A8 (HP-IB) boards. They are referred to collectively as the HP-IB section. The power supply circuit blocks are on
the A1 (main), the A2 (control), the A4 (FET), and the A5 (diode) boards. They are referred to collectively as the power
section.

The flowchart of Figure 3-1 provides troubleshooting isolation procedures to guide you either to the appropriate circuit or to
one of the detailed troubleshooting procedures in this section. The purpose of the flowchart is only to isolate the problem to
a specific area of the power supply. If you have already isolated the problem, proceed directly to the applicable
troubleshooting section.

Table 3-1 lists the error codes that may appear on the front panel when the unit performs its internal selftest. Along with the
error codes, the table also identifies various circuits or components that may have caused that error code to appear.

In the Power Section Troubleshooting, Tables 3-10 and 3-11 give various power supply symptoms that identify the
corresponding board, circuit or components that may have caused that symptom. The symptoms in Table 3-10 may become
apparent when running the Performance Tests in Section 2.

HP-IB Section Troubleshooting

The HP-IB section troubleshooting consists of primary and secondary interface troubleshooting. Signature analysis is
required to troubleshoot the primary and secondary processor as well as the front panel board. Other circuits on the HP-IB
board, such as the voltage and current DACs, can be checked using either signature analysis or the front panel controls. The
readback circuits cannot be checked using signature analysis. Figure 3-2 illustrates the test setup that allows access to the
HP-IB board components for troubleshooting.

To remove the HP-IB board, perform the HP-IB board removal procedure discussed earlier in this section. Lay out the
board as shown in Figure 3-2 with a piece of insulating material under the board. Reconnect connectors W1, W2, W5, and
W6 after the board is on the insulating material.

Note: The HP-IB board can be placed alongside the unit for troubleshooting by using extender cables provided
in service kit HP P/N 06033-60005.

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 Figure 3-1. Troubleshooting Isolation

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 Figure 3-1. Troubleshooting Isolation (continued)

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 Table 3-1. Selftest Error Code Troubleshooting

Error Code Description Check Functional Circuit

ERROR 4 External RAM Test Replace A8U8
ERROR 5 Internal RAM Test Replace A8U14
ERROR 6 External ROM Test Replace A8U6
ERROR 7 HP-IB Test Replace A8U17
ERROR 8 HP-IB address set to 31
ERROR 10 Internal ROM Test Replace A8U4
ERROR 12 ADC Zero Too High Check U11,20,24,66,67; go to Readback DAC Troubleshooting
ERROR 13 Voltage DAC Full Scale Low Check U2,7,64,69
ERROR 14 Voltage DAC Full Scale High Check U2,7,64,69
ERROR 15 Voltage DAC Zero Low Check U2,7,64,69
ERROR 16 Voltage DAC Zero High Check U2,7,64,69 Go to Secondary SA
ERROR 17 Current DAC Full Scale Low Check U9,65,68 Troubleshooting
ERROR 18 Current DAC Full Scale High Check U9,65,68
ERROR 19 Current DAC Zero Low Check U9,65,68
ERROR 20 Current DAC Zero High Check U9,65,68

Primary Interface Troubleshooting

Primary interface troubleshooting checks for the presence of bias voltages, clock signals (see Figure 3-3), and activity on the
data lines. Primary signature analysis may be used to further troubleshoot these circuits, but since the address and data lines
go to so many IC’s, it may not be cost-effective to narrow an incorrect signature to a specific chip. HP-IB board replacement
may be the most cost-effective solution.

Note: The initialization procedure in Page 28 must be performed when the HP-IB board is replaced.

Figure 3-2. HP-IB Board Test Setup

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 Figure 3-3. Clock and Primary SA Waveforms

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 +5V and PCLR Circuits:

Node Measurement
U1-8 ≈ 3.5Vdc
U1-2 = 4Vdc
U1-3 = 4.2Vdc
U1-4 = 4.2Vdc
U1-6 ≈50mVdc

Clock Signals (see clock waveforrns in Figure 3-3)

Node Measurement Source

C7+,C8+ = 12MHz (see waveform) Y2
J5-8 = 6MHz (see waveform) U14
U35-12 ≈ 50mVdc (see waveform) U35

Data Lines Check that all data and address lines are toggling. Address and data lines go to the following IC’s:

Address Lines Data Lines

U6: A0 to A15 U6: D0 to D7
U8: A0 to A15 U8: D0 to D7
U12: A0 to A4 U12: D0 to D7
U14: A8 to A15 U14: D0 to D7
U16: A0 to A7 U16: D0 to D7
U17: A0 to A2 U17: D0 to D7
U36: A7 to A15

Note: Data and address lines may not toggle if one line is shorted either high or low. If no short is found, replace
all socketed IC’s. If the data lines still do not toggle, replace the HP-IB (A8) assembly.

Node Measurement
A0 to A15 Toggling
D0 to D7 Toggling

Secondary Interface Troubleshooting

Secondary interface troubleshooting checks the operation of the voltage, current, and readback DACs as well as analog
multiplexer and secondary microprocessor. The analog multiplexer is checked in the Readback DAC troubleshooting
procedure. The secondary microprocessor can only be checked using secondary SA (refer to Signature Analysis).

Voltage and Current DAC

The voltage and current DACs can be checked either from the front panel or by secondary SA. Refer to Signature Analysis
to troubleshoot the voltage and current DACs in this manner.

Note: To troubleshoot the voltage and current DACs from the front panel if the unit has failed selftest, place
jumper A8J5 in the skip selftest position (see Table 3-2). This lets you operate the unit even though it fails
the internal selftest.

Use the front panel controls to vary the output voltage and current from zero to full-scale output. Remember to turn off the
unit and connect a short across the output before programming the current from zero to full scale. Use a DMM and check
the voltages at the following nodes:

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 CV DAC Circuits

Node Setup Measurement

U69-6 Voltage set to 0. 0V
Voltage set to max. + 5V

U64-6 Voltage set to 0. 0V

Voltage set to max. -10V

CC DAC Circuits

Node Setup Measurement

U68-6 Current set to 0. 0V
Current set to max. + 5V

U65-6 Current set to 0. 0V

Current set to max. -10V

Readback DAC Circuits

Refer to Figure 3-4 for the waveforms to troubleshoot the readback circuits.

The turn-on selftest waveforrn at U24-7 is obtained by toggling the on/off switch repeatedly to perform the selftest routine.
If this waveform is not correct, isolate the problem either to the readback DAC or the multiplexer.

Note: To troubleshoot the readback DAC from the front panel if the unit has failed selftest, place jumper A8J5
in the skip selftest position (see Table 3-2). This lets you operate the unit even though it fails the internal
selftest.

Use the front panel controls to vary the output voltage from zero to full-scale output to obtain the waveforms at U67-6.
These waveforms check the operation of the readback DAC.

To check the multiplexer, use the front panel controls to obtain the waveforms at the output of the multiplexer (U24-2).
Remember to turn off the unit and connect a short across the output before programming the current from zero to full scale.
Press "OVP DISPLAY’’ on the front panel to display the OV_MON portion of the waveforms.

If the waveforms are not correct, use the front panel controls and a DMM to check the multiplexer input voltages at the
following nodes:

Readback Multiplexer (U20):

Node Setup Measurement

U20-9 Voltage set to 0. 0V
Voltage set to max. + 5V

U20-10 Current set to 0. 0V

Current set to max. + 5V

U20-11 OV set to 0. 0V
OV set to max. +2.2V

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 Figure 3-4. Readback and Secondary SA Waveforms

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 Signature Analysis

Perform the signature analysis only after you have completed the Primary Processor Troubleshooting.

The easiest and most efficient method of troubleshooting microprocessor-based instruments is signature analysis. Signature
analysis is similar to signal tracing with an oscilloscope in linear circuits. Part of the microcomputer memory is dedicated to
signature analysis and a known bit stream is generated to stimulate as many nodes as possible within the circuit. However,
because it is virtually impossible to analyze a bit stream with an oscilloscope, a signature analyzer is used to compress the
bit stream into a four-character signature that is unique for each node. By comparing signatures of the unit under test to the
correct signatures for each node, faults can usually be isolated to one or two components. Note that signature analysis
provides only go/no-go information; the signature provides absolutely no diagnostic information.

The following general notes apply to signature analysis of the power supply.

1. Be certain to use the correct setup for the signature being examined.
2. Most signatures are taken on the HP-IB, and front panel assemblies.
3. Note the signatures for Vcc and ground on the I.C. being examined. If an incorrect signature is the same as that of Vcc
or ground, that point is probably shorted to Vcc or ground.
4. If two pins have identical signatures, they are probably shorted together. If two signatures are similar, it is only
coincidence. For example, if the signature at a certain point should be 65C4, a signature of 65C3 is not "almost right".
No diagnostic information can be inferred from an incorrect signature.
5. If a signature is incorrect at an input pin, but is correct at its source (output of previous I.C.), check for printed circuit
and soldering discontinuity.
6. An incorrect signature at an output could be caused by a faulty component producing that output; or, a short circuit in
another component or on the board could be loading down that node.

Tables 3-2 and 3-3 show the primary, front panel, and secondary signature analyzer connections that are required to perform
the SA tests in Tables 3-4 through 3-8. Remember that the primary and secondary circuits each reference a different circuit
common.

Primary SA

Place the unit in primary SA mode by moving the J5 jumper as shown in Table 3-2. Connect the signature analyzer as
shown in the table. The front panel display should indicate: ’’SA SA", and all LED’s will be on. If the display is different,
replace U14.

Note: The power supply will not go into SA mode if one of the data and address lines is shorted either high or
low. Refer to Data Lines troubleshooting.

When the unit is in SA mode, check for the waveforms shown in Figure 3-3. Refer to Table 3-4 for the primary SA
signatures. Return the J5 jumper to its normal position when the primary signature analysis is complete.

Front Panel SA

To place the unit in SA mode for Front Panel SA troubleshooting, follow the procedure for Primary SA troubleshooting.
When the unit is in SA mode, check the signatures in Tables 3-5 through 3-7.

The signatures in Table 3-5 check the registers that drive the 7-segment LED displays. Most problems will involve only one
display or LED indicator. Table 3-6 checks the address latches and decoders. Address latch U15 forwards address data to
the address decoders, which enable the shift registers. Table 3-7 checks flip-flop U12, shift register U11, and gate U18. U12
decodes the output of the RPG. U11 and U18 are used by the microprocessor to read the status of the RPG and front panel
switches.

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 Return the J5 jumper to its normal position when the front panel signature analysis is complete.

Secondary SA

For secondary SA troubleshooting, connect the signature analyzer as shown in Table 3-3. Use a jumper wire and short U4
pin 21 to common (U4 pin 20). Check for the waveforms in Figure 3-4 and the signatures in Table 3-8 for the secondary
SA. When the secondary signature analysis is complete, disconnect the jumper on U4 pin 21.

Table 3-2. Primary and Front Panel Signature Analyzer Test Setups

SIGNATURE EDGE PRIMARY SA

ANALYZER INPUT SETTING CONNECTIONS
CLOCK A8J5 pin 8
START A8U37 pin 16
STOP A8U37 pin 16
GROUND A8J5 pin 5
A8J5 (in SA mode)

A8J5 JUMPER POSITIONS

Jumpering pins 1 and 2 skips the internal
selftest when the unit is turned on.
Jumpering pins 3 and 4 places U37 in SA mode.
Jumpering pins 5 and 6 is the normal/operating
position of the jumper.

Table 3-3. Secondary Signature Analyzer Test Setups

SIGNATURE EDGE SECONDARY SA

ANALYZER INPUT SETTING CONNECTIONS
CLOCK A8U4 pin 23
START A8U4 pin 22
STOP A8U4 pin 22
GROUND A8U4 pin 20

A8U4 JUMPER POSITIONS

Use a jumper wire and connect A8U4 pin 21 to pin 20 (ground).

Use a 40-pin test clip (Pomona Model 5240 or eq.) to facilitate test
connections to A8U4.

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 Table 3-4. Primary Processor Signature Table
(A8U6 = P/N 5080-2160 REV A.00.00, A.00.01, A.00.02 and A.00.04)

A.00.04 A.00.02 A.00.01 A.00.00

A(0) A46A A46A A46A A46A U16-12 U6-12 U8-12 U12-11 U17-21
A(1) 4148 UH8O UH8O UH8O U16-13 U6-11 U8-11 U12-13 U17-22
A(2) 72F5 82H5 UO39 4FU1 U16-14 U6-10 U8-10 U12-9 U17-23
A(3) PAU8 9899 HOPF 86C2 U16-15 U6-9 U8-9 U12-10
A(4) A4A7 3088 O7FA 5A37 U16-16 U6-8 U8-8 U12-8
A(5) 45OP 48H5 5823 PHHO U16-17 U6-7 U8-7
A(6) C3UU UF3H 2682 3F6U U16-18 U6-6 U8-6 U36-11
A(7) HOU4 HOU4 F6OP HFP3 U16-19 U6-5 U8-5 U36-9
A(8) 4U39 4U39 17AF 17AF U14-52 U6-27 U8-27 U36-8
A(9) 45A8 45A8 62H1 62H1 U14-51 U6-26 U8-26 U36-7
A(10) 278A 278A OOU3 OOU3 U14-50 U6-23 U8-23 U36-6
A(11) 6OA3 6OA3 6OA3 6OA3 U14-49 U6-25 U8-25 U36-5
A(12) 7826 7826 7826 7826 U14-48 U6-4 U8-4 U36-4
A(13) 5850 5850 5850 585O U14-47 U6-28 U8-28 U36-3
A(14) F93H F93H F93H F93H U14-46 U6-29 U8-3 U36-2
A(15) 79UA 79UA 79UA 79UA U14-45 U6-3 U8-31 U36-1

D(0) PH2F 48P2 48P2 48P2 U14-60 U16-9 U6-13 U8-13 U12-22 U17-12
D(1) HU9O 6O84 6O84 6O84 U14-59 U16-8 U6-14 U8-14 U12-21 U17-13
D(2) U665 74UH 96C5 HA6P U14-58 U16-7 U6-15 U8-15 U12-20 U17-14
D(3) 53PP 16A9 UH79 8OC2 U14-57 U16-6 U6-17 U8-17 U12-19 U17-15
D(4) C9C2 196F AA13 U64C U14-56 U16-5 U6-18 U8-18 U12-18 U17-16
D(5) C27C 132C 8A9F 89AP U14-55 U16-4 U6-19 U8-19 U12-17 U17-17
D(6) HO18 4387 497F 2C5F U14-54 U16-3 U6-20 U8-20 U12-16 U17-18
D(7) P97H 4FC3 33AO U44P U14-53 U16-2 U6-21 U8-21 U12-15 U17-19

WR* FP65 FP65 FP65 FP65 U14-40 U8-29 U36-12

RD* unstable 3PPH 3PPH 3PPH U14-61 U6-24 U8-24 U36-13
ALE U665 4OAP 4OAP 4OAP U14-62 U16-11
READY 26C3 26C3 26C3 26C3 U14-43 U36-15

BANK_SEL unstable 5AHH unstable unstable U14-27 U36-14

EE(0) 7CF1 7CF1 7CF1 7CF1 U14-19 U70-1

EE(1) AH32 AH32 AH32 AH32 U14-20 U70-2
EE(2) HCCH HCCH HCCH HCCH U14-21 U70-3
EE(3) 9P5F 9P5F 9P5F 9P5F U14-22 U704

APC 9361 9361 9361 9361 U14-23 U15-22

UART CHU5 CHU5 CHU5 CHU5 U12-14 U36-16
HPIB 2688 2688 2688 2688 U36-17 U17-8
ROM C95F C95F C95F C95F U6-22 U36-19
RAM 9UPU 9UPU 9UPU 9UPU U8-22 U36-18

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 Table 3-5. Front Panel LED Display and Indicator Drivers
(A8U6 = P/N 5080-2160 REV A.00.00, A.00.01, A.00.02 and A00.04 Inputs)

Inputs:
Node Measurement
U1 to U10-1 6H15
U1 to U10-9 Cycle power to unit--Lo to Hi after approx. 160 ms
U1 to U10-2,14 +5V
U1 to U10-7 common
U1-8 F05U
U2-8 50A9
U3-8 6F42
U4-8 AH52
U5-8 51U7
U6-8 PHFF
U7-8 5730
U8-8 8U73
U9-8 HU9C
U10-8 5AHH

Outputs:

Current Display Voltage Display

6υυυυυυυ7υυυυυυυυυ 6υυυυυυυ7υυυυυυυυ
8 υ8
U1 U2 U3 U4 U5 U6 U7 U8 U9 U10
pin 3 5AHH 102A 4A3F 5AHH 5AHH 4U91 7499 5AHH CHP5 0000
pin 4 5AHH 92FF C665 5AHH 5AHH 31U5 4475 5AHH P3PP 0000
pin 5 5AHH 4FUC 5526 5AHH 5AHH 739H P7AH 5AHH H8HC 0000
pin 6 5AHH 94F0 C4A9 5AHH 5AHH 5724 OUC4 5AHH 84PU 0000
pin 10 5AHH 102A A73P 5AHH 5AHH 4U91 1467 5AHH 5UAU 0000
pin 11 5AHH 92FF PFP6 5AHH 5AHH 31U5 U810 5AHH U7A8 0000
pin 12 5AHH 4FUC 163C 5AHH 5AHH 739H HA84 5AHH A60U 0000
pin 13 5AHH 94F0 lAP8 5AHH 5AHH 5724 C4HC 5AHH 56PA 0000

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 Table 3-6. Front Panel Address Latches and Decoders
(A8U6 = P/N 5080-2160 REV A.00.00, A.00.01, A.00.02 and A.00.04 Inputs)

Inputs:
Node Measurements
U14-26 Toggling (unstable)
U14-35 37F8
U14-38 1ABC

U15-9, U17-3,6 Cycle power to unit--Lo to Hi after approx. 160 rns

U17-4,5 Cycle power to unit--Hi to Lo after approx. 160 rns

Outputs:

U13-1, U14-1, U15-3 969U U14-5, U16-6 F615 U16-5, U17-12 9C3C
U13-2, U14-2, U15-4 C7AA U14-13 Toggling U16-12, U17-8 4056
U13-3, U14-3, U15-5 A372 U14-14 5AHH U16-13, U17-10 Toggling
U13-4, U14-4, U17-11 Toggling U14-15 HU9C U17-1 37F8
U13-5, U16-3 5C91 U15-1, U17-2 6H15 U17-2
U13-6, U14-6, U17-9 1ABC U15-2 +5V
U13-7 8U73 U15-3
U13-9 5730 U15-6, U16-2, U17-3 FlP6
U13-10 PHFF U15-8, U16-11 P62F
U13-11 51U7 U15-10, U16-1,4,10 9H84
U13-12 AH52
U13-13 6F42
U13-14 50A9
U13-15 F05U

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 Table 3-7. Front Panel RPG Latches and Input Port
(A8U6 = P/N 5080-2160 REV A.00.00, A.00.01 A.00.02, and A.00.04)

Inputs:
Node Measurement
U11-1 1ABC
U11-2 U12-4,10 Toggling (unstable)
U16-10 9H84

Procedure:

Node
S1 LCL released U11-13 Lo U11-7, U16-9 Lo U16-8 Hi
S1 LCL depressed U11-13 Hi U11-7, U16-8,9 Toggling

S2 OUTPUT ADJUST released U11-14 Lo U11-7, U16-9 Lo U16-8 Hi

S2 OUTPUT ADJUST depressed U11-14 Hi U11-7, U16-8,9 Toggling

S3 DISPLAY OVP released U11-3 Lo U11-7, U16-9 Lo U16-8 Hi

S3 DISPLAY OVP depressed U11-3 Hi U11-7, U16-8,9 Toggling

S4 DISPLAY SETTINGS released U11-4 Lo U11-7, U16-9 Lo U16-8 Hi

S4 DISPLAY SETTINGS depressed U11-4 Hi U11-7, U16-8,9 Toggling

S5 FOLDBACK released U11-5 Lo U11-7, U16-9 Lo U16-8 Hi

S5 FOLDBACK depressed U11-5 Hi U11-7, U16-8,9 Toggling

U12-5 Node toggles when RPG is rotated clockwise

U12-9 Node toggles when RPG is rotated in either direction
Set scope for dual trace operation, 2V/div, 10 ms/div, normal triggering, and positive edge on channel A.
Connect channel A to U12-3 and channel B to U12-2.

U12-3 Rotate RPG CW

U12-2 Rotate RPG CW

U12-3 Rotate RPG CCW

U12-2 Rotate RPG CCW

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 Table 3-8. Secondary Processor Signature Table

DS(0) P36U U4-1 U7-15 U9-15 U11-15

DS(1) 2280 U4-2 U7-14 U9-14 U11-14
DS(2) 4277 U4-3 U7-13 U9-13 U11-13
DS(3) 720F U4-4 U7-12 U9-12 U11-12
DS(4) 6A31 U4-5 U7-11 U9-11 U11-11
DS(5) 662U U4-6 U7-10 U9-10 U11-10
DS(6) 6020 U4-7 U7-9 U9-9 U11-9
DS(7) 6327 U4-8 U7-8 U9-8 U11-8
DS(8) 1377 U4-39 U7-7 U9-7 U11-7 U2-16
DS(9) FF99 U4-38 U7-6 U9-6 U11-6 U2-17
DS(10) 236P U4-37 U7-5 U9-5 U11-5 U2-18
DS(11) H495 U4-36 U7-4 U9-4 U11-4 U2-19

WR* 9FU7 U4-12 U7-17

WR* 9FF7 U4-13 U9-17
WR* 9FHU U4-14 U11-17
F817 U4-26 U20-1
36U7 U4-27 U20-16
0562 U4-28 U20-15
ISTX 9F97 U4-11 U2-4, 14
9FH6 U4-17 U2-2
9FH5 U4-16 U2-11
ALE 0000 U4-30 U2-1
AU68 U4-35
+ 5V 9FA8 U4-33,34

Power Section Troubleshooting

Table 3-9 describes the signals at each of the control board test points. The test connector provided in service kit P/N
5060-2865 allows easy connection to each test point. The measurements given here include bias and reference voltages as
well as power supply status signals. It provides conditions for these measurements and gives the components which are the
sources of the signals. Tables 3-10 and 3-11 describe possible symptoms in the power section. Both give lists of circuit
blocks or components which can cause the symptoms shown. The appropriate assembly is also given.

If the supply exhibits a symptom given in Table 3-10 or 3-11, go to the block which pertains to that symptom. If the exact
symptom seen is not in the tables, start with the symptom that seems to be closest to the one observed. The blocks are given
in the Power Section Blocks section starting on Page 50. Troubleshooting information for each block will include a brief
description of the circuit. The columns provided are as follows:

NODE: This column lists the nodes where the measurements should be taken. In some cases this will be
stated as NODE( + ) and NODE(-) where the first is the test node and the second is the reference.

SETUP: If a certain setup is required for the measurement, it will be given in this column.

MEASUREMENT: This column indicates what the expected measurement is for the given node.

SOURCE: If applicable, the components which generate the signal will be provided in this column.

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 To troubleshoot the power supply the A4 power FET board and A2 control board can be raised out of the unit using
extender boards and cables provided in service kit P/N 5060-2865.

Main Troubleshooting Setup

Figure 3-5 shows the troubleshooting setup for troubleshooting all of the unit except the front panel and initial no-output
failures (see Page 49). The external power supply provides the unit’s internal bus voltage. The ac mains connects directly to
the unit’s A1T3 bias transformer via the isolation transformer, thereby energizing the bias supplies, but it does not connect
to the input rectifier and filter to create the bus voltage. With the external supply the unit operates as a dc-to-dc converter.
The supply biases A4Q3, and A4Q4 PFETs with a low voltage rather than the 320Vdc bus voltage. This protects the PFETs
from failure from excess power dissipation if the power-limit comparator or the off-pulse circuitry are defective. It also
reduces the possibility of electrical shock to the troubleshooter.

Figure 3 5. Main Troubleshooting Setup

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 An isolation transformer provides ac voltage that is not referenced to earth ground, thereby reducing the
possibility of accidentally touching two points having high ac potential between them. Failure to use an
isolation transformer as shown in Figure 3-5 will cause the ac mains voltage to be connected directly to
many components and circuits within the power supply, including the FET heatsinks, as well as to the
terminals of the external dc power supply. Failure to use an isolation transformer is a definite personal-
injury hazard.

The troubleshooting setup of Figure 3-5 connects high ac voltage to A1F1, A1S2, the fan, and
other components and circuits along the left edge of the A1 main board.

As a convenience in implementing the troubleshooting setup, modify a spare mains cord set as shown in Figure 3-6. This
facilitates connecting the unit’s power receptacle to the external supply and connecting the bias transformer to the ac mains.

With the mains cord unplugged proceed as follows:

a. Remove the top cover and the inside cover per Page 31. Set switch S4 (front-left corner of the A1 main board) in the
TEST position.

Failure to set switch S4 in the TEST position will result in damage to the power supply, damage to the
external dc supply, and is an electrical shock hazard to you.

a. Install control board test connector onto the A2J3 card-edge fingers.
b. Connect a 50Ω 10-W load resistor to the unit’s output terminals.
c. With the LINE switch off, connect an external dc power supply to the outside prongs of the unit’s power receptacle.
Ignore polarity as the unit’s input rectifying diodes steer the dc power to the correct nodes.
d. Complete the setup of Figure 3-5 by attaching an ac mains cord to test points TP1 (L, black wire) and TP2 (N, white
wire) and connect the green ground wire to the unit’s case ground terminal or a suitably grounded cabinet screw. TP1
and TP2 are accessible through the cutout on the left side of the unit and are at the left edge of the A1 main board.

Troubleshooting No-Output Failures

No-output failures often include failure of the A4Q4 PFETs and their fuses A4F1 and A4F2. When either the off-pulses or
the power-limit comparator fails, the PFETs can fail from excessive power dissipation. The strategy for localizing no-output
failures is to check the voltages and waveforms at the control board test connector to predict if that circuit failure would
cause the FETs to fail. This makes it possible to develop your troubleshooting approach without an extensive equipment
setup. Proceed as follows:

a. With the mains cord disconnected remove the A4 FET board per Page 32. Connect the mains cord and switch on
power.
b. Using Table 3-9 check the bias voltages, the PWM-OFF and PWM-ON Control signals and other signals of interest at
the A2 control board test fingers, A2J3.
c. Check for the presence of program voltages, VP and IP, at the rear panel.
d. Check for presence of the 320Vdc rail voltage between the cathodes of diodes A1CR1 and A1CR2 and the anode of the
diodes A1CR3 and A1CR4. If there is no rail voltage, check diodes A1CR1 through A1CR4.

Diodes AlCR1 through A1CR4 connect to the ac mains voltage. Use a voltmeter with both input
terminals floating to measure the rail voltage.

a. Select the functional circuit for troubleshooting based on your measurements and Table 3-11, which provides direction
based on the status of the PWM OFF and PWM ON signals.

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 ..

Figure 3-6. Modified Mains Cord Set For Troubleshooting

Power Section Blocks

This section contains the blocks referenced in Tables 3-10 and 3-11.

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 Table 3-9. Control Board Test Connector, A2J7

PIN NO. SIGNAL NAME Vdc WAVEFORM/CONDITIONS SOURCE

Digital-Circuits Bias & Reference Voltages
1 +5V 5.0 A2Q3 (emitter)
22 + 20V(5V UNREG) 20.0 with 120Hz & 45KHz ripple AlCR6, AlCR7
14 2.5V ref 2.50 A2U9 (OUT)
6 0.5V ref 0.50 A2R79,A2R80

Analog-Circuits Bias Voltages

2 +15V 15.0 A2U12 (OUT)
21 -15V -15.0 A2U4 (OUT )

Status Signals
17 CV TTL Lo if in CV operation A2Q6C-7 (collector)
16 CC TTL Lo if in CC operation A2Q6F-14 (collector)
13 OV TTL Hi if not OVP shutdown A2U11D-11
11 DROPOUT TTL Hi if ac mains okay A2U17D-11
12 OT TTL Hi if not overtemp shutdown A2U11B-6

Control Signals
25 PWM OFF 1.7µs TTL pulses, 20KHz U1A-5
26 PWM ON 1.7µs TTL pulses, 20KHz U2B-6
18 Ip MONITOR 1V pk, ½ sawtooth, 20KHz A2CR26 (cathode)
(at full power only)
8 INHIBIT TTL Hi if not remotely inhibited A2R185C, U19A-2
15 DOWN PROGRAM 1.2-3.0 while not down programming A2CR21, A2CR27

7 OVP PROGRAM 1/10 OVP (6033A) e.g.: 2Vdc if OVP set to full
1/30 OVP (6038A) voltage output A3R6 (wiper)
5 OV CLEAR +5V inverted OV reset line A8U4-35
19 PCLR2 +5V if +5V bias OK A2Q60-9
Commons & Current-Monitor
4 COMMON 0.0 common return for all bias A2C20(-), A2R50
voltages, status and control
signals
9 COMMON 0.0 common return for 2.5V ref and A2R83, A21-20
0.5V ref
10 I-TEST ≈0.005 (6033A). inboard-side monitoring res A1R27 &A1R28, A1T2
≈0.055 (6038A)
3 V-MON-BUF V-OUT/12 trimmed V-MON for readback A8U25-6

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 Table 3-10. Performance Failure Symptoms

DEFECTIVE
SYMPTOMS BOARD CHECK FUNCTIONAL CIRCUITS
unexplained OVP shutdowns A2 OVP circuit, CV circuit
no current limit A2 CC circuit
max current < 10Adc (6038A) A2 CC Clamp, CC circuit
< 30Adc (6033A)
max power < specified A2, A1 Power Limit, 20KHz clock, transformer AlT1
max voltage < 60Vdc (6038A) A2, A1 CV Circuit, diodes A1CR1-CR4
< 20Vdc (6033A)
cycles on & off randomly A2, A1 AC-Surge-&-Dropout Detector, Mains Voltage
Select switch A1S2
CV overshoots A2 A2U10A, A2CR20, A2R94
output noise (<1KHz) A2,A1 CV circuit, input filter
output noise (>1KHz) A1, A4 transformer AlT1, Output Filter, snubbers
A4R7/R8/C5/CR5/, A4R13/
R14/C6/CR6, A4R33/C13
CV regulation, transient A2, A1 wrong sensing
response, programming time low ac mains voltage, CV circuit
CC regulation A2 low ac mains voltage, CC circuit
CV oscillates with capacitive A2 A2R10, A2C51, A2R95, A2R96, A2R86,
loads A2C47, A2R71, A2C36
CC oscillates with inductive A2 A2U10, A2R86, A2C47, A2C43, A2R77, A2U3D
loads A2U3D, A2R30, A2C44, A2R76, A2R75,
A2C42, A2C41, A2R1

Table 3-11. No-Output Failures

(Bias supplies and AC turn-on circuit functioning)

Status of FET On/Off-Pulses

PWM-ON PWM-OFF DEFECTIVE

A2J3-26 A2J3-25 BOARD CHECK FUNCTIONAL CIRCUITS
Lo Lo A2 Control ckts: CV & CC thru On- & Off-Pulse Oneshots *
Lo Hi A2&A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed
Hi Lo A2&A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed
Hi Hi A2&A4 PWM and DC-to-DC Converter: A4Q3 and A4Q4 probably failed
Lo N A2 A2U17B, On-Pulse Oneshot and A2Q6A
N Lo A2&A4 Off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed
Hi N A2&A4 A2U17B, On-Pulse Oneshot & DC-to-DC: A4Q3 and A4Q4 probably
failed
N Hi A2&A4 Off-Pulse Oneshot and DC-to-DC: A4Q3 and A4Q4 probably failed
N N A2&A4 Power-Limit Comparator and DC-to-DC: A4Q3 and A4Q4 probably
failed
Lo= TTL low Hi= TTL high N= normal 20KHz pulse train, TTL levels
* Decide which to troubleshoot--the CV circuit, the CC circuit, or the PWM and Off-Pulse & On-Pulse Oneshots-- by
measuring the CV CONTROL (A2CR24, cathode) and the CC CONTROL (A2CR19 cathode) voltages. Troubleshoot
whichever is negative, and if neither is negative, troubleshoot the PWM. Make these voltage measurements after you
have implemented the Main Troubleshooting Setup.

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 Troubleshooting AC-Turn-On Circuits

Relay AlK1 closes at 1.0 seconds and DROPOUT goes high at 1.1 seconds after 20V (5V UNREG) reaches about 11Vdc.
DROPOUT high enables the PWM if OVERVOLTAGE , INHIBIT , and OVERTEMP are also high.

Circuits Included. AC-Surge-&-Dropout Detector, Bias Voltage Detector, U11A, 1-Second Delay and Relay Driver--all on
A2 control board.

Setup. The Main Troubleshooting Setup, Page 48. Apply the ac mains voltage to the bias transformer, and set the external
supply to 0Vdc.

Inputs:

NODE (+) * SETUP MEASUREMENT SOURCE

A2J3-1 wait 2s 5.0Vdc A2Q3 (emit.)
A2J3-22 20Vdc A1CR6, A1CR7
A2U20-8, 10 f.w.rect, 1-2V pk A1CR8,A1CR9
A2U22-13 TTL sq wave, 20KHz A2U22-6

Outputs:

NODE SETUP MEASUREMENT

A2U20-5 cycle power transition 0 to 13.5Vdc
A2U20-2 cycle power transition 0 to 1.4Vdc
A2Q6-1 cycle power transition 0 to 5.0 to 0.3Vdc
A2Q6-9 cycle power transition 0 to 0.3 to 5.0Vdc
A2U20-6 wait 2s < 0.25Vdc
A2U20-1, 14 wait 2s Hi (5Vdc)
A2U11-3 cycle power transition Lo to Hi to Lo
A2U18-10 cycle power burst 1.25khz sq. wave, 1.1s
A2U18-13 cycle power five 100ms pulses then Hi
A2U18-12 cycle power two 200ms pulses then Hi
A2U18-15 cycle power transition Lo to Hi at 800ms
A2U17-8 cycle power transition Lo to Hi at 1.0s
A2U17-11 cycle power transition Lo to Hi at 1.1s
( DROPOUT )
A2Q5 (col.) cycle power transition 5.0 to 0.3Vdc at 1.0s
(RELAY ENABLE)

Troubleshooting DC-To-DC Converter

Parallel NOR gates A4U2A, A4U2B and A4U1A act as drivers and switch on PFETs A4Q3 and A4Q4 through pulse
transformer A4T1. NOR gate A4U1B turns off the PFETs through pulse transformer A4T2 and transistors A4Q1 and
A4Q2.

Circuits Included. On-Pulse Driver, Off-Pulse Driver, PFET Switches and Drivers on A4 power mesh board.

Setup. The Main Troubleshooting Setup, Page 48. Apply the ac mains voltage to the bias transformer, set the external
supply to 40Vdc, and switch on the LINE switch. Set the unit’s output voltage to 20Vdc and current to above 1Adc. Verify
that the OVERRANGE LED lights. See Figure 3-7 for waveforms.

Inputs:

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 NODE (+) NODE (-) MEASUREMENT SOURCE
A2J3-26(PWM-ON) VM waveform #1 A2Ul7-6,A2P1-7, A4P1-24,C
A2J3-25(PWM-OFF) VM waveform #2 A2U13-5,A2P1-13,A4P1-26,A
A4Q3-D A4Q4-S 39Vdc A1C4 ( + ),A4P1-10,A,C
A1C4 ( - ),A4P1-4,A,C

Outputs:

NODE (+) NODE (-) MEASUREMENT

A4Q3-G A4Q3-S waveform #3
A4Q4-G A4Q4-S waveform #3
A4Q3-D A4Q3-S waveform #4
A4Q4-D A4Q4-S waveform #4
A2J3-18 A2J3-4 waveform #5

Note: The Gate (G) and Source (S) leads of PFETs A4Q3 and A4Q4 can be accessed from the circuit side of the
board and used as test points. The Drain (D) of A4Q3 can be picked up at its case or from the cathode of
A4CR13. The Drain of A4Q4 can be picked up at its case or from the anode of A4CR14.

If all the INPUT measurements are correct but the OUTPUT Vgs waveform (3) is incorrect, the problem may be caused by
weak PFETs. Two 6800pF capacitors (HP PN 0160-0159) can be substituted for the PFETs (G to S) to check waveform 3.
If the waveform is still incorrect, the problem may be located in the drive components. If you replace the PFETs, replace
both the PFETs and associated drive components as furnished in PFET Service Kit. HP Part No. 5060-2860.

The PFETs are static sensitive and can be destroyed by relatively low levels of electrostatic voltage.
Handle the A4 power mesh board and the PFETs only after you, your work surface and your equipment
are properly grounded with appropriate resistive grounding straps. Avoid touching the PFET’s gate and
source pins.

Troubleshooting Bias Supplies

+5V On A2 Control Board. The PWM A2U6 includes a clock generator (45KHz set by A2R53 and A2C26), and a
current limit (2Adc set by 0.15Vdc across A2R50). It turns off each output pulse using the difference between the voltage
at voltage divider A2R46-A2R47 and the 2.5Vdc set by voltage regulator A2U5.

Circuit Included. +5Vdc bias supply circuitry from connector pins A2P1-15 through jumper A2W3 on A2 control board.

Setup. The Main Troubleshooting Setup, Page 48. Apply the ac mains voltage to the bias transformer, and set the external
supply to 0Vdc.

Input:

NODE MEASUREMENT SOURCE

A2J3-22 ≈ 20Vdc A1CR6,A1CR7

Outputs:

NODE MEASUREMENT
A2U6-6 ≈2 to 4Vdc sawtooth, 45KHz
A2U6-12,13 ≈ 19V pk, 15µs pulses, 45KHz

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 A2Q3 (emit) ≈ 20V pk, 5µs pulses, 45KHz
A2U5 (OUT) 2.5 Vdc
A2R50, A2CR11 (anode) ≈ 0 >V > 0.007Vdc
A2R46, A2R47 2.5 Vdc

To check if load on + 5V is shorted, remove jumper A2W3

+15V On A2 Control Board. Voltage regulator A2U12 regulates the voltage across resistor A2R29 to be 1.25Vdc. That
sets the current through zener diode A2VR1 at 7.5mAdc. The output voltage is 1.25Vdc plus 11.7Vdc across A2VR1 plus
the voltage across A2R34.

Circuit Included. +15Vdc bias supply circuitry from connector pin A2P1-27 through test point A2J3-2 on A2 control
board.

Setup. The Main Troubleshooting Setup, Page 48. Apply the ac mains voltage to the isolatlon transformer, and set the
external supply to 0Vdc.

Input:

NODE MEASUREMENT SOURCE

A2U12(IN) ≈ 24Vdc A1U1, A1C1 (+)
A2C17 (+)

Outputs:

NODE ( + ) NODE (-) MEASUREMENT

A2U12 (OUT) A2U12 (ADJ) l.25Vdc
A2U12 (cath.) A2U12 (anode) 11.7Vdc
A2VR1 (anode) A2R34, A2R33 2.05Vdc
A2LR3 (cath.) A2VR3 (anode) 6.2Vdc

To check if load on +15V is shorted, remove jumper A2W1.

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 Figure 3-7. Waveforms

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 -15 V On A2 Control Board. Voltage regulator A2U4 regulates the voltage across resistor A2R32 to be 1.25Vdc.

Circuit Included. -15 Vdc bias supply circuitry from connector pin A2P1-30 through test point A2J3-21 on A2 control
board.

Setup. The Main Troubleshooting Setup, Page 48. Apply the ac mains voltage to the bias transformer, and set the external
supply to 0Vdc.

Input:

NODE (+) MEASUREMENT SOURCE

A2U4(IN), A2C16 (-) ≈ - 24Vdc A1U1, A1C1(+)

Outputs:

NODE ( + ) NODE (-) MEASUREMENT

A2U4 (ADJ) A2U24 (OUT) l.25Vdc
A2VR2 (cath.) A2VR2 (anode) 11.7Vdc
A2R33, A2R34 A2VR2 (cath.) 2.05Vdc

To check if load on -15V is shorted, remove jumper A2W3.

Refer to Down Programmer, for the + 8.9Vdc bias supply, and refer to OVP Circuit, for the + 2.5V bias supply.

Troubleshooting Down Programmer

The down programmer loads the output when either MASTER ENABLE is low or CV ERROR is more negative than about
- 6Vdc. Comparator A4U3B triggers down programming when the voltage at A4U3B-5 is less than about 3Vdc. The
collector-emitter current through transistor A4Q6 increases as the output voltage decreases because of feedback from
voltage divider A4R24-A4R27 at A4U3A-2

Circuit Included. Down programmer and 8.9V bias supply on A4 power mesh board.

Setup. The Main Troubleshooting Setup, Page 48, except connect the external supply to the unit’s + OUT ( + ) and - OUT
( - ) terminals. Apply the ac mains voltage to the bias transformer. Set the external supply (EXTERNAL) and adjust the
unit’s voltage setting (INTERNAL) as instructed below.

Outputs:

Set Voltage (Vdc)

NODE External Internal Setup Measurement
A4U4 (OUT) - - 8.9Vdc
A4U3B-7 0 2 unplug TS1 0Vdc
A4U3B-7 10 0 reconnect TS1 0Vdc
A4U3B-7 0 2 7.8Vdc
A4U3A-2 0 2 unplug TS1 0.43Vdc
A4R26 0 2 ≈0.41Vdc (6038A)
0.2Vdc (6033A)
A4Q6 (base) 20 2 1.0Vdc
A4U3A-1 20 2 4.0Vdc
A4R26 20 2 ≈0.34Vdc (6038A)
≈0.11Vdc (6033A)

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 Troubleshooting CV Circuit

V-MON, the output of CV Monitor Amp A2U7 is the voltage between + S and - S. CV Error Amp A2U8 compares
V-MON to CV PROGRAM. Innerloop Amp A2U10A stabilizes the CV loop with IVS input from A2U10C. The
measurements below verify that the operational amplifier circuits provide expected positive and negative dc voltage
excursion when the CV loop is open and the power mesh shut down.

Circuits Included. Constant Voltage (CV) Circuit and buffer amplifier A2U10C.

Setup. The Main Troubleshooting Setup, Page 48. Apply the ac mains voltage to the bias transformer, and disconnect the
external supply. Remove the + S jumper and connect A2J3-2 ( +15V) to + S. Set MODE switch settings B4, B5 and B6 all
to 0. Set VP to 0Vdc by connecting to P or set VP to + 5Vdc by connecting to A2J3-1 according to SETUP below.

Outputs:

NODE SETUP MEASUREMENT

VM 3.75Vdc
A2U10C-8 4.7Vdc
A2U8-6 VP = 0 -14Vdc
A2U10A-1 VP = 0 -14Vdc
A2U8-6 VP = 5 4.7Vdc
A2U10A-1 VP = 5 5.1Vdc

If the failure symptoms include output voltage oscillation, check if the CV Error Amp circuit is at fault by shorting A2U8-6
to A2U8-2. If oscillations stop, the CV Error Amp circuit is probably at fault.

Troubleshooting CC Circuit

I-MON, the output of CC Monitor Amp A2U1, in volts is 1/6 the output current in amperes. CC Error Amp A2U2B
compares I-MON to CC PROGRAM. Differentiator circuit A2U3D and A2U3C, stabilizes the CC loop. It differentiates
IVS and has a voltage gain of 16. Its output is summed with CC PROGRAM at CC Error Amp A2U2B.

The measurements below verify that the operational amplifier circuits provide expected positive and negative dc voltage
gain when the CC loop is open and the power mesh shut down.

Circuits Included. Constant Current (CC) Circuit on A2 control board.

Setup. The Main Troubleshooting Setup, Page 48, except connect the external supply with polarity reversed to the unit’s +
OUT ( - ) and - OUT ( + ) terminals. Apply the ac mains voltage to the bias transformer. Set the external supply to 3.0Adc
constant current with a voltage limit in the range 5 to 20Vdc. Set IP to 0Vdc by connecting to P or set IP to +5Vdc by
connecting to A2J3-1 according to the following SETUP.

Outputs:

NODE SETUP MEASUREMENT

IM 0.50Vdc
A2U2B-7 IP=0 -14Vdc
A2U2B-7 IP=5 6.0Vdc
A2U3D-13 +0.015Vdc
A2U3C-9 +0.015Vdc
A2U3C-8 +0.25Vdc

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 If the failure symptoms include output current oscillation, check if the differentiator circuit is at fault by removing resistor
A2R16. If oscillations stop, the differentiator is probably at fault.

Troubleshooting OVP Circuit

Comparator A2U14D sets, and gate A2U17A resets flipflop A2U14B-A2U14C. TTL low at A2U14-1,8,13 inhibits the
PWM.

Circuit included. OVP Circuit and 2.5V bias supply on A2 control board.

Setup. The Main Troubleshooting Setup, Page 48, except connect the external supply to the unit’s + OUT ( + ) and - OUT
(-) terminals. Apply the ac mains voltage to the bias transformer. Adjust the unit’s OVP limit to 15Vdc. Set the external
supply (EXTERNAL) as instructed below.

Outputs:

SET VOLTAGE
NODE EXTERNAL (Vdc) SETUP MEASUREMENT
A2U9 (OUT) - 2.5Vdc
A2U14-10 10 1.0Vdc
A2U14-11 - 1.5Vdc
A2J3-13 10 Hi
A2J3-13 20 Lo
A2J3-13 10 Lo
A2J3-13 10 cycle power Hi

Note: Connecting a test probe to either input of either comparator in the OV Flipflop (pins A2U14-1, 6, 7, 8, 9,
14 or A2U11-13) may cause the flipflop to change states and cause the probed input to be low.

Troubleshooting PWM & Clock

The inputs to Inhibit Gate A2U19A and PWM gate A2U19B are the keys to PWM troubleshooting. The 20KHz Clock
starts each PWM output pulse, and the pulse stops when any of the inputs to A2U19A or A2U19B goes low. The PWM is
inhibited and prevented from initiating output pulses as long as any of the eight inputs are low.

Circuit Included. Pulse Width Modulator (PWM), Inhibit Gate A2U19A, Off-Pulse Oneshot, On-Pulse Oneshot, A2U17B,
20KHz Clock.

Setup. The Main Troubleshooting Setup, Page 48. Apply the ac mains voltage to the bias transformer and switch on the
LINE switch. Adjust the unit’s current setting above 1.0 Adc. Set the extemal supply (EXTERNAL) and adjust the unit’s
voltage setting (INTERNAL) as instructed below.

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 Inputs:

NODE SETUP MEASUREMENT SOURCE

A2J3-1 5.0Vdc A2Q3 (emitter)
A2U19-1 Hi A2U17D-11
A2U19-2 Hi remote inhibit
A2U19-4 Hi A2U14-1,8
A2U19-5 Hi A2U11B-6
A2U19-10 Hi A2U16-7
A2U19-12 POWER LIMIT fully Lo A2U14-2
CCW
A2U19-12 POWER LIMIT fully Hi A2U14-2
CCW

Outputs:

SET VOLTAGE (Vdc)

NODE EXT. INT. SETUP MEASUREMENT
A2U21-7 0 0 TTL sq wave, 320KHz
A2U22-3 0 0 TTL sq wave, 160KHz
A2U22-6 0 0 TTL sq wave, 20KHz
A2U13-5 0 0 23.5µs TTL pulses, 20KHz
A2U13-9 0 0 23.5µs TTL pulses, 20KHz
A2U14-2 40 0 POWER LIMIT fully Lo
CCW
A2U19-8 40 0 Lo
A2U13-9 40 0 Lo
A2U17-6 40 0 Lo
A2U13-13 40 0 Lo
A2U13-5 40 0 Lo
A2U17-6 40 0 POWER LIMIT fully groups of 4 pulses, 1.7µs, TTL, 20KHz
CCW
A2U13-5 40 0 1.7µs, TTL, 20KHz
+OUT 40 15 ≈ 12.2Vdc (OVERRANGE); 6038A
3.8Vdc (OVERRANGE); 6033A
+OUT 40 2 2.0Vdc (CV)
+OUT 40 2 short A2J3-4 to A2J3-8 0.0Vdc

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 4
Principles of Operation

Introduction

This chapter contains block diagrams, simplified schematics, and related descriptions of the power supply. The instrument
can be thought of as comprising two major sections: the HP-IB, microcomputer, and interface circuitry; and the power mesh
and control circuits. Block diagrams represent the HP-IB board, the front panel board, and the power mesh and control
board. The descriptions associated with these block diagrams explain the function of each block without describing how
individual components within the circuit accomplish that function. Detailed descriptions are provided only for those
individual circuits whose operation may not be obvious to the user.

The circuit names and layouts of the block diagrams are the same as used on the complete schematics; however, some items,
such as bias supplies, are left off the block diagrams for clarity. In general, circuits are described as they appear on the
diagrams from left to right. Signal names that appear on the drawings are printed in capitals in the descriptions, as are
front-panel labels for indicators and controls. Signal names that describe an operating mode or condition are active when
that condition exists. For example, OT is high and OT is low if an overtemperature condition exists. Signal flow is from left
to right and top to bottom, unless arrows indicate otherwise.‘

The following paragraphs describe the HP-IB and the front-panel board. These circuits provide the interface between the
power mesh circuits and the controller and/or operator. The HP-IB and front-panel boards are referenced to earth common.
Isolation is achieved by optical isolators on the HP-IB board. Data is sent between boards serially.

HP-IB Board

Circuits on the HP-IB board, see Figure 4-1, provide the interface between the power supply and the user, generate the
fault/inhibit and relay controls signals (DFI/RI), and supply the analog control and reference signals for the power mesh and
readback circuit. Two microprocessors (primary and secondary) control all data communication between the power supply
and the user. Additional circuits on the HP-IB board include the serial interface ports, address switches, an EEPROM, and
status registers.

Primary Microprocessor

The primary microprocessor controls the HP-IB/serial link interface, the front panel data communication, and the DFI/RI
interface. It communicates with the secondary microprocessor through two serial link data lines that are optically coupled to
provide the proper isolation of the user interface from the power mesh. The HP-IB board also has a ROM, which contains
the operating firmware, and a RAM, which stores variables such as programmed voltage and current and readback values.

Address Switches

The primary microprocessor determines the HP-IB address by reading the address switch settings. Two of the address
switches determine the power-on SRQ state and the DFI/RI port setting.

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 Figure 4-1. HP-IB Block Diagram

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 EEPROM

The primary microprocessor determines the power supply ID, start-up parameters, calibration constants and scale factors by
reading the factory-initialized EEPROM.

Isolation

Two optical isolators transmit serial data between the primary and secondary microprocessors while maintaining electrical
isolation between the controller/user-interface and the power mesh.

Secondary Microprocessor

The secondary microprocessor translates the serial data from the primary microprocessor into a parallel data bus and other
control signals. Values are loaded into the voltage, current, and readback DAC via the data bus. The secondary
microprocessor also controls the analog multiplexer, which is used when reading back the actual output.

Digital-to-Analog Converters

Output voltage and current are controlled by two 12-bit DACs whose digital inputs are directly connected to the secondary
microprocessor. The microprocessor programs the DACs according to data received over the HP-IB or from the front panel
rotary pulse generator. The DAC circuits also include buffers and compensation amplifiers.

The 12-bit readback DAC is connected to the input of a comparator where it’s output is compared to the unknown voltage
output of the analog multiplexer. The secondary microprocessor programs the output of the readback DAC starting with the
MSB and continuing down to the LSB. Each bit is programmed either on or off until the output of the DAC is closest to the
unknown voltage output of the multiplexer. At this point, the microprocessor returns the programmed value of the readback
DAC.

Analog Multiplexer

The analog multiplexer selects one of five input voltages to be compared to the readback DAC. This comparison allows the
microprocessor to determine the value of the input voltage. The five inputs of the multiplexer are: CV_PROG and
CC_PROG, which are only used during selftest, at power-on, or in response to the TEST? query when the supply is
disabled; OV_MON, which represents the overvoltage trip setting; and I_MON and V_MON, which represent the measured
values of output current and voltage.

Status Inputs

The status inputs from the main board provide the following status information to the secondary microprocessor. They are:
CC, which is set when the supply is operating in constant current mode; CV, which is set when the supply is in constant
voltage mode; AC_FAULT, which signals that ac power has dropped below the minimum operating voltage of the supply;
OT, which indicates an overtemperature condition has occurred on the supply; and OV, which indicates an overvoltage has
occurred on the supply.

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 Front Panel Board

The front-panel board, see Figure 4-2, contains the VOLTS and AMPS display circuits, the rotary pulse generator (RPG)
and RPG decoders, five pushbutton switches, mode indicators, and the OVP ADJUST potentiometer. Data from the
microprocessor is shifted to the display circuits via DATA DOWN , and data from the front-panel controls circuits is
shifted to the microprocessor via DATA UP. Circuits on the front-panel board operate from bias voltages supplied from the
HP-IB board, and are referenced to the same common as the HP-IB board (earth ground). The OVP ADJUST potentiometer
is part of the power mesh control circuitry (referenced to power supply negative output), and is not connected to any circuits
on the front-panel board.

Address Latches and Decoders

DATA DOWN bits received while D / A is low are latched and decoded in this circuit, which then steers clock pulses to
the addressed circuit when D / A goes high.

Volts and Amps Output Ports and Displays

These circuits display values sent by the microprocessor via DATA DOWN. Normally, these are the actual output voltage
and current readings. Pressing the DISPLAY SETTINGS switch causes the microprocessor to send the voltage and current
values that have been sent by the controller (remote) or RPG (local). If the unit is in CV mode, the voltage display should
show the same reading for actual and set values; the current display will switch from the actual value to the current limit. In
CC mode, the current readings will be the same and the voltage display will switch from actual value to the voltage limit.
Pressing the DISPLAY OVP switch causes the voltage display to show the OVP trip voltage that has been set.

The microprocessor also uses the readout to display the HP-IB address switch settings, self-test error messages, and
readback overrange conditions.

RPG and Latches

When rotated, the RPG products two pulse trains that are 90 degrees phase shifted from each other, with the phase
relationship determined by the direction of rotation. This circuit contains two flip-flops that monitor the RPG outputs. The
output of one flip-flop goes low to indicate that the RPG has been rotated, and the output of the other goes low to indicate
CW rotation or high to indicate CCW rotation. This data is loaded into an input port when D / A is low, and the flip-flops
are set back to their quiescent state by clock pulses from the address decoder when the input port is addressed.

Because the microprocessor reads the input approximately every millisecond, it can determine if the RPG is being turned
rapidly (for a large change) or slowly (for fine adjustment), and the microprocessor varies the rate it changes the DAC
inputs accordingly.

Front-Panel Switches and Input Port

Five front-panel pushbutton switches plus the two RPG flip-flop outputs are connected to this input port. Data is loaded
when D / A is low, and is shifted out by clock pulses from the address decoders. The microprocessor reads data in via
DATA UP approximately every millisecond, and checks the switches every 10ms, thereby ensuring that even rapid switch
operations will be captured.

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 Figure 4-2. Front Panel Block Diagram

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 Mode Indicators

The front-panel mode indicators are controlled by the microprocessor via DATA DOWN and the mode indicator output
ports and latches. DATA DOWN signals are shifted in by clock pulses from the address decoders.

OVP Adjust Control

The OVP ADJUST potentiometer sets the voltage level at which the overvoltage protection (OVP) circuit trips.

Power Clear

The power clear signal ( PCLR ) from the HP-IB board goes low when the unit is turned on, and remains low until the bias
power supplies have stabilized. This low level resets the display-circuit latches on the front panel board, causing all
indicators and display segments to turn on and remain on until the microprocessor updates the display (approximately one
second).

Power Mesh and Control Board

The basic operating concepts of the power mesh and control circuits are described in the following paragraphs. The
beginning paragraphs describe the basic difference between an autoranging power supply and a conventional CV/CC power
supply in terms of the available output, and provide an overview of the basic theory of operation. Later paragraphs describe
the functions of the individual circuits on the power mesh and control board.

Overview

The basic difference between an autoranging power supply and conventional types of Constant Voltage/Constant Current
(CV/CC) power supplies can be seen by comparing the maximum-output-power characteristics of each. A conventional
CV/CC power supply can provide maximum output power at only one combination of output voltage and current, as shown
in Figure 4-3a. The range of a power supply can be extended by designing an instrument with two or more switch-selectable
voltage/current ranges within the maximum power-output capability, as shown in Figure 4-3b. An autoranging power supply
provides maximum output power over a wide and continuous range of voltage and current combinations, as shown in Figure
4-3c, without the operator having to select the proper output range.

The unit is a flyback-type switching power supply, so-called from the flyback technique of generating high voltage in
television receivers. Energy is stored in the magnetic field within a transformer while current flows in the primary, and is
transferred to the secondary circuit when current flow in the primary is turned off. Current flow in the primary is controlled
by FET switches which are turned on and off at a 20KHz rate by a pulse width modulator. Regulation is accomplished by
controlling the on time of the FET switches. On pulses are initiated by a clock circuit. Off pulses are initiated when current
flow in the primary has stored enough energy for the output circuit, which is determined as follows.

Sense voltages representing the actual output voltage and current are compared to reference voltages set either by
front-panel controls or remote programming signals. These comparisons produce a control voltage, which represents the
amount of power required by the output circuit. Current flow in the primary circuit produces a ramp voltage that represents
the amount of energy being stored for transfer to the output circuit. An off pulse is generated when the ramp voltage exceeds
the control voltage. It can be seen that the power available in the output circuit corresponds to the duty cycle of the FET
switches.

Figure 4-4 shows the relationship of various signals associated with the FET on/off cycle.

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 Figure 4-3. Output Characteristics; Typical, Dual Range, and Autoranging Supplies

Figure 4-4. FET Control Signals Timing Diagram

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 Figure 4-5 is a block diagram of the power mesh. These circuits convert the ac input power to approximately 300Vdc, and
convert this dc voltage to the proper dc output voltage.

AC Turn-On Circuits

Primary power comes to the input rectifier through a resistor which limits turn-on inrush current to the input filter. Jumper
A1W5 connects the input rectifier and filter as a voltage doubler for 100/120Vac power lines. This jumper is not used for
220/240Vac; thus the input filter develops a dc bus voltage of about 300Vdc for either 100/120 or 220/240Vac power line
voltages. Primary power also comes through line-voltage select switches to the bias power supplies, which provide the
internal operating voltage for the power supply. The line-voltage select switches connect the primary winds of the
bias-supplies transformer for operation at 100, 120, 220, or 240Vac.

The unit checks that the + 5Vdc bias voltage and the ac power line voltage are within acceptable limits as part of its turn-on
sequence. When + 5Vdc comes up, the bias voltage detector resets the overvoltage protection circuit, enables the on-pulse
driver for the PFET switches, and with the ac-surge-&-dropout detector starts the 1-second-delay circuit. After one second,
relay A1K1 bypasses the inrush current-limiting resistor. After 0.1 seconds more, the 1-Second-Delay circuit enables the
PWM through the DROPOUT signal. The power supply can then provide output power.

When the ac-surge-&-dropout detector detects high or low line voltage, the unit shuts down until an acceptable power-line
voltage returns. Then it repeats the above turn-on sequence. This protects the unit from damage from power-line surges and
brownouts.

DC-to-DC Converter

PFET switches A4Q3 and A4Q4 control current flow from the Input Filter through power transformer T1. The PWM
creates on- and off-pulses for the PFETs. A train of on pulses comes through diodes A4CR4 and A4CR3 to the PFETs’ gates
to turn on the PFETs. The PFETs’ input capacitances hold the PFETs on between on pulses. Off pulses turn on transistors
A4Q1 and A4Q2 which then short the PFETs’ input capacitances and turn off the PFETs.

The on-pulse one-short A2U15B and off-pulse one-shot A2U15A generate the on and off pulses. A2U15A produces a train
of 160 KHz on pulses during the PWM output pulse. Off pulse one-short A2U15A triggers an off pulse at each trailing edge
of the PWM output pulses. Figure 4-5 shows the timing. Driver circuits increase the current drive capability before applying
the pulses to pulse transformers A4T1 and A4T2.

When the PFETs turn on, current flows through the primary of power transformer AlT1 and primary-current monitor
transformer A4T3. The output rectifier A4CR7 is reverse biased and blocks current flow in the AlT1 secondary.
Consequently, the AlT1 transformer stores energy. When the PFETs apply the dc bus voltage to the primary, the primary
current ramps up, storing more and more energy. The A4T3 transformer senses the AlT1 primary current, and the secondary
of A4T3 develops the Ip-RAMP VOLTAGE across resistor A2R108. This linearity increasing voltage predicts the
correction in the supply’s output voltage or current which will occur when the PFETs are turned off. Comparators
monitoring the Ip-RAMP VOLTAGE signal the PWM to turn off the PFETs when Ip-RAMP VOLTAGE exceeds either the
CP CONTROL-PORT voltage or the POWER-LIMIT reference voltage.

When the PFETs turn off, the collapsing magnetic field reverses the polarity of the voltages across the AlT1 primary and
secondary, and current flows from the A1T2 secondary through output rectifier A4CR7 to charge output capacitor A1C8,
A1C9 and A1C10. When the PFETs turn off, the leakage inductance of T1 forces the current to continue to flow in the
primary. Flyback Diodes A4CR13 and A4CR14 protect the PFETs from excess reverse voltage by conducting this current
around the PFETs and back to the input filter.

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 Down Programmer

This circuit allows the output voltage to be lowered rapidly when required. In order to lower the output voltage it is
necessary to discharge the output filter capacitors (typically, through the load). In situations that require the output voltage
to drop more rapidly than can be accomplished through the load, the Down Programmer discharges the capacitors and pulls
the output line low. Five conditions can conditions can trigger down programming: programming of a lower output voltage,
overvoltage, overtemperature, remote disable, or primary power failure. The Down Programmer turns on when either
MASTER ENABLE is low or the CV ERROR VOLTAGE is more negative than about -6Vdc.

The + 8.9Vdc bias supply for the Down Programmer stores enough energy in its input capacitor to operate the Down
Programmer after loss of primary power. This ensures that the Down Programmer will be able to discharge the output
circuit completely when primary power is turned off.

Bleeder Circuit (6038A only)

This circuit enables the output capacitor to discharge faster by providing ample bleed current at various output levels,
(thereby improving Down Programming times). The path for the bleed current is provided by one of two transistors, A1Q1
or A1Q2. At output voltages below 13 to 15.5Vdc, transistor A1Q2 is turned on to supply milliamperes of bleed current.
When the output voltage is above 13 to 15.5Vdc, transistor A1Q1 is turned on, turning off A1Q2.

Fuse A1F3 provides protection to internal components should A1Q2 short and draw excessive current. Down programming
response time at no load will be considerably longer if components malfunction in the bleeder circuit or if fuse A1F3 is
blown.

Constant-Voltage (CV) Circuit

The constant-voltage circuit compares the output voltage to the user-set CV PROGRAM VOLTAGE to produce CV
CONTROL VOLTAGE. Two comparison amplifier loops accomplish the comparison. In the outerloop, CV error amplifier
A2U8 compares V-MON, a buffered fraction of the sensed output voltage OVS, to the programming voltage from the HP-
IB board, to create the CV ERROR VOLTAGE. Then in the innerloop, amplifier A2U10A compares this error voltage to
IVS, a buffered fraction of the innerloop output voltage, to produce the CV CONTROL VOLTAGE. The CV ERROR
VOLTAGE is also diode-OR connected through diode A2CR21 as an input to the down programmer.

V-MON also connects through protective circuitry to rear-panel terminal VM for remote monitoring of the output voltage.
As output varies from zero to full scale, V-MON varies from 0 to + 5 volts.

Settings of the CV programming switches--the B6, B5 and B4 MODE switch settings--allow the CV PROGRAM
VOLTAGE to come from the HP-IB board, from an external voltage applied between rear-panel terminals VP and P, or
from an external resistor between VP and P. When using an external resistor, current from the CV constant-current source
flows through the applicable resistance to develop the CV PROGRAM VOLTAGE.

In CV mode the CV CONTROL VOLTAGE varies between about - 0.5Vdc and about + 1.0Vdc. It is most negative when
the load is drawing no power. As the load draws more power, the voltage becomes more positive. The CV CONTROL
VOLTAGE is at the cathode of diode A2CR24, part of the diode-OR input to the control-voltage comparator. Diode
A2CR20 prevents voltage overshoots during transient load changes and program changes.

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 Constant-Current (CC) Circuit

The constant-current circuit compares the output current user-set CC PROGRAM VOLTAGE to produce CC CONTROL
VOLTAGE. As with the CV Circuit, two comparison amplifier loops accomplish the comparison. OCS is the voltage across
current-monitoring resistors A1R27 and A1R28, and it senses the output current for the outerloop. To compensate for the
fraction of the output current which flows through the unit’s output-voltage sensing resistors, CC monitor amplifier A2U1
adds a fraction of VMON to OCS. It amplifies both to produce the outerloop current-sense voltage, I-MON.

I-MON also connects through protective circuitry to rear-panel terminal IM for remote monitoring of the output current. As
output varies from zero to full scale, I-MON varies from 0 to + 5 volts.

Differentiation of IVS develops a current proportional voltage which senses the interloop current flowing into the capacitive
output filter. CC error amplifier A2U2B sums this differentiated innerloop voltage with I-MON and compares the sum to the
CC PROGRAM VOLTAGE to produce CC CONTROL VOLTAGE. In CC mode the CC CONTROL VOLTAGE varies
between about -0.5 Vdc and about +1.0Vdc at the cathode of diode A2CR19. CC clamp A2U2A limits CC PROGRAM
VOLTAGE to about 5.6 peak volts.

Settings of the rear-panel CC programming switches--the B3, B2 and B1 MODE switch settings--allow the CC PROGRAM
VOLTAGE to come from the HP-IB board, from an external voltage applied between terminals IP and P, or from an
external resistor between IP and P. When using an external resistor, current from the CC constant-current source flows
through the resistance to develop CC PROGRAM VOLTAGE.

Overvoltage Protection (OVP) Circuit

The OVP circuit monitors the power supply output voltage and compares it to a preset limit determined by a front-panel
OVP ADJUST potentiometer. If the output voltage exceeds the limit, the OVP Circuit initiates a PWM OFF pulse, which
also triggers the Down Programmer. The OVP Circuit latches itself until it receives OV CLEAR or ac power is turned off.
The bias voltage detector resets the OVP at turn-on of the unit.

Power-Limit Comparator

Two comparisons with Ip-RAMP VOLTAGE provide POWER LIMIT and CONTROL V LIMIT, two of the four inputs for
the PWM. Power Limit is the output of the Power Limit Comparator A2U14A. The comparator compares Ip-RAMP
VOLTAGE with the power-limit reference voltage of about 1.0Vdc. The reference is adjustable with the POWER LIMIT
calibration trim pot A2R25. POWER LIMIT sets the maximum primary current in power transformer AlT1 by going low
and turning off the PWM when Ip-RAMP VOLTAGE exceeds the reference.

Primary current is approximately proportional to output power, and POWER LIMIT turns off the PWM when the
CONTROL V LIMIT would otherwise allow the unit to deliver more than about 200 watts. This occurs during transient
load increases, step increases in CV PROGRAM VOLTAGE and when the combination of the CV PROGRAM VOLTAGE
and the CC PROGRAM VOLTAGE calls for more than 200 watts. The power-limit comparator produces the power-limited
portion of the unit’s output characteristic curve in Figure 4-3 and is the essence of the unit’s autoranging characteristic.

Control-Voltage Comparator

The control-voltage comparator A2U16 produces the CONTROL V LIMIT input to the PWM by comparing Ip-RAMP
VOLTAGE to CP CONTROL-VOLTAGE. In CV or CC operation CP is one diode-drop more than the lower of the CV and
CC CONTROL VOLTAGE. CONTROL V LIMIT goes low and turns off the PWM when Ip-RAMP VOLTAGE exceeds
CP. The A2R113-A2R114 voltage divider steers control of CP by its connection at the anodes of series diodes A2CR19 and
A2CR24. The A2R113-A2R114 voltage divider sets the maximum CP voltage to + 1.5Vdc. As an illustration of CV-CC
selection, suppose the unit is in CV operation and diode A2CR24 is forward biased by a low CV CONTROL VOLTAGE:

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 then CV sets CP to less than + 1.5Vdc. CV keeps diodes A2CR19 reverse biased and prevents CC control until the CC
CONTROL VOLTAGE is even lower.

The lower of the control voltages varies between about - 0.5Vdc and + 1.0Vdc regulating the unit’s output. The higher
control voltage has no effect on the output and increases in response to the error voltage in its circuit. When higher, the CC
CONTROL VOLTAGE limits at about 6Vdc. When higher, the CV CONTROL VOLTAGE increases only slightly. In CV
or CC mode CP remains one diode drop more than the lower control voltage and varies from about 0.0 to + 1.5Vdc. In
UNREGULATED mode CP is + 1.0Vdc.

Initial-Ramp Circuit

The control voltage and ramp voltage waveforms in Figure 4-4 show that there is a time delay between when the control
voltage is exceeded and when the PFETS turn off. This cumulative circuit delay causes the PFETS to deliver power even
when no power is requested by the control circuits. To eliminate the delay, the initial-ramp circuit adds a ramp voltage to
Ip-RAM VOLTAGE at the input to the control voltage comparator. The added ramp voltage starts with the 20KHz clock
pulse and causes the combined-ramp voltage to exceed the control voltage earlier, thereby essentially eliminated the PFET
turn-off delay. A two-state RC integrating network consisting of resistors A2R116 and A2R117 and capacitors A2C59 and
A2C61 creates the initial ramp by shaping the 20KHz clock pulses.

Pulse-Width Modulator (PWM)

The PWM generates 20 KHz repetition-rate pulses which vary in length according to the unit’s output requirements. The
pulses start 1.5µs after each 20KHz clock pulse and turn off when any of these four inputs go low: The output of the
control-voltage comparator (CONTROL V LIMIT ), the output of the power-limit comparator (POWER LIMIT), the 20
KHz clock pulse (50% duty cycle limit), or the output of the inhibit gate A2U19A (MASTER ENABLE). As discussed on
Page 68, the PFETs turn on during and turn off at the trailing edges, respectively, of PWM output pulses.

The PWM generates pulses as follows: a 20KHz dock pulse holds the 1.5µs-delay flip-flop A2U13B reset; 1.5µs after the
trailing edge of the 20KHz pulse, the next pulse from the 320 KHz clock oscillator clocks the output of A2U13B high, and
this initiates the PWM pulse from PWM flip-flop A2U13A. When one of the above four inputs to AND-gate A2U19B goes
low, A2U19B resets A2U13A, and the PWM pulse turns off.

Bias Voltage Detector

The bias voltage detector prevents spurious operation, which might occur at turn-on, of the unit if circuits tried to operate
before the + 5Vdc bias voltage is at the clock, PWM, and logic circuits. After turn-on, as the output of the + 5Vdc bias
supply rises from 0Vdc through 1Vdc, three transistor switches in the Bias Voltage Detector turn on. They inhibit the Relay
Driver and the On-Pulse Driver, and they create the power clear signal, PCLR2 . The transistors inhibit the circuits and hold
PCLR2 low until the unregulated input to the + 5Vdc bias supply is greater than about 11Vdc, an input voltage sufficient to
assure + 5Vdc bias output. PCLR2 resets the OVP at turn-on.

AC-Surge-&-Dropout Detector

The ac-surge-&-dropout detector protects the unit from damage from power line voltage surges and dropouts by shutting
down the unit when there is either a 40% overvoltage or a 20ms voltage interruption in the ac power line voltage. The
detector shuts down the unit by inhibiting the PWM through the DROPOUT signal from the 1-Second Delay circuit. Line
Detect signal, which is fullwave-rectified ac from the + 5Vdc secondary of the bias-supplies transformer, senses the power
line voltage.

The dropout detector, including comparators A2U20A and A2U20D, operates by enabling a capacitor timing ramp when
UNE DETECT ceases. Comparator A2U20C monitors the amplitude of UNE DETECT to provide highline voltage
detection.

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 1-Second-Delay Circuit

The 1-second-delay circuit is the heart of the unit’s controlled turn on. It causes relay A1K1 to bypass inrush
current-limiting resistor A1R1 one second after turn on, and it enables the PWM 0.1 second later. When either the output of
the ac-surge-&-dropout detector or PCLR2 is low NAND gate A2U11A holds the circuit reset. The circuit starts counting
at 1/16 the clock frequency (1.25 KHz) when both inputs to A2U11A are high and causes RELAY ENABLE to go high in
1.0 seconds and DROPOUT to go high in 1.1 seconds. When DROPOUT goes high, it stops the count, and it enables the
PWM.

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 5
Replaceable Parts

Introduction

This chapter contains information for ordering replacement parts. Table 5-3 lists parts in alpha-numeric order by reference
designators and provides the following information:

a. Reference Designators. Refer to Table 5-1.

b. Hewlett-Packard model in which the particular part is used.
c. Hewlett-Packard Part Number.
d. Description. Refer to Table 5-2 for abbreviations.

Parts not identified by reference designator are listed at the end of Table 5-4 under Mechanical and/or Miscellaneous.

Table 5-1. Reference Designators

A Assembly
B Blower
C Capacitor
CR Diode
DS Signaling Device (light)
F Fuse
FL Filter
G Pulse Generator
J Jack
K Relay
L Inductor
Q Transistor
RT Thermistor Disc
S Switch
T Transformer
TB Terminal Block
TS Thermal Switch
U Integrated Circuit
VR Voltage Regulator (Zener diode)
W Wire (Jumper)
X Socket*
Y Oscillator

* Reference designator following "X" (e.g. XA2) indicates assembly or device mounted in socket.

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 Ordering Information

To order a replacement part, address order or inquiry to your local Hewlett-Packard sales office. Specify the following
information for each part: Model, complete serial number, and any Option or special modification (J) numbers of the
instrument; Hewlett-Packard part number; circuit reference designator; and description. To order a part not listed in Table
5-3, give a complete description of the part, its function, and its location.

Table 5-2. Description Abbreviations

ADDR Addressable
ASSY Assembly
AWG American Wire Gauge
BUFF Buffer
CER Ceramic
COMP Carbon Film Composition
CONV Converter
DECODER/DEMULTI Decoder/Demultiplexer
ELECT Electrolytic
EPROM Eraseble Programamble Read-Only Memory
FET Field Effect Transistor
FF Flip-Flop
FXD Fixed
IC Integrated Circuit
INP Input
LED Light Emitting Diode
MET Metalized
MOS Metal-Oxide Silicon
OP AMP Operational Amplifier
OPTO Optical
OVP Over Voltage Protection
PCB Printed Circuit Board
PORC Porcelain
POS Positive
PRIOR Priority
ROM Read-Only Memory
RAM Random Access Memory
RECT Rectifier
REGIS Register
RES Resistor
TBAX Tube Axial
TRlG Triggered
UNI Universal
VAR Variable
VLTG REG Voltage Regulator
WW Wire Wound

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 Table 5-3. Replaceable Parts List

Ref. Desig. HP Model HP Part Number Description

A1 6033A 06023-60021 Main Board Assembly
6038A 06038-60021 Main Board Assembly
C1 both 0160-7606 cap 1µF +10% 50Vac
C2,3 both 0180-3426 cap 590µF +50-10% 400V
C4 both 0180-3427 cap 300µF +50-10% 200V
C5 both 0160-7606 cap 1µF +20% 250V
C6,7 both 0160-5933 cap 0.022µF 10% 1500V
C8-10 6033A 0180-3425 cap 5500µF l0V
6038A 0180-3548 cap 1700µF 75V
C11,12 6033A 0160-5377 cap 2.2µF l00V
6038A 0160-6167 cap 2.2µF 63V
C13,14 both 0160-7731 cap 0.22µF 10% 1500V
C15,16 both 0160-4355 cap 0.01µF +10% 250V
C17 6033A 0160-5422 cap 0.047µF +20% l00V
6038A 0160-4834 cap 0.047µF +20% 50V
C20,21 both 0180-3428 cap 1000µF 50V
C22,23 both 0160-4439 cap 4700pF +20% 250V
C24,25 both 0160-4281 cap 2200pF 20% 250V
C26 both 0160-4323 cap 0.047µF 20% 250V
CR1-4 both 1901-1199 diode-power rectifier 600V 3A
CR6,7 both 1901-0731 diode-power rectifier 400V 1A
CR8,9 both 1901-0050 diode-switching 80V 200rnA
CR13-15 both 1901-0731 diode-power rectifier 400V 1A
F2 both 2110-0007 fuse 1A 250V
F3 6038A 2110-0763 fuse, 1/4A 125V
J1 both 1251-5927 connector, 26-contact
J2 both 1251-5384 connector, 3-contact
J3 both 1251-8676 connector, 5-contact
K1 both 0490-1417 relay, DPST
L1 both 06024-80094 choke, RFI, 3A (magnetic core 9170-0721)
L3 6033A 5080-1981 choke 0.5µH
6038A 9140-0987 choke 3µH
Q1 6038A 1854-0087 transistor, NPN SI
Q2 6038A 1854-0799 transistor, NPN SI TIP41C
R1 both 0811-3667 res 20 5% 7W
R2 6033A 0811-1856 res 250 1% 5W
6038A 0811-1865 res 2K 1% 5W
R3 6033A 5080-2007 res 0.0005 (current sense)
R4 both 0683-1025 res 1K 5% 1/4W
R5 6033A 8151-0013 wire, tinned copper, AWG 22
6038A 7175-0057 wire, tinned copper, AWG 22
R6 both 0683-1025 res 1K 5% 1/4W
R7 6038A 0699-1210 res 80K 0.1% 0.lW
R8 6033A 8151-0013 wire, tinned copper, AWG 22
6038A 0699-0118 res 20K 0.1% 0.lW
R9 6033A 8151-0013 wire, tinned copper, AWG 22
6038A 7175-0057 wire, tinned copper, AWG 22

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

R10 6033A 8151-0013 wire, tinned copper, AWG 22
6038A 0698-6359 res 80K 0.1% 1/8W
R11 both 0698-6322 res 4K 0.1% 1/8W
R12 both 0698-8695 res 36K 0.1% 1/8W
R14 6033A 0698-3572 res 60.4 1% 1/8W
R15 6033A 8151-0013 wire, tinned copper, AWG 22
6038A 0757-0270 res 249K 1% 1/4W
R17,18 both 0683-1005 res 10 5% 1/4W
R19 both 0683-1055 res 1M 5% 1/4W
R20,21 both 0811-1867 res 15K 5% 5W
R22,23 both 0686-1065 res 10M 5% 1/2W
R24,25 both 0686-1035 res 10K 5% 1/2W
R26 both 0683-3315 res 330 5% 1/4W
R27A,28B 6038A 0811-3823 res 0.1 5% 20W (current sense)
R29 both 0686-3335 res 33K 5% 1/2W
R30 6038A 0811-1865 res 2K 1% 5W
R31 6038A 0812-0098 res 135 5% 5W
R32 6038A 0683-1035 res 10K 5% 1/4W
R33 6038A 0683-4745 res 470 5% 1/4W
R34 6038A 0683-2035 res 20K 5% 1/4W
S2 both 3101-1914 switch 2-DPDT, slide
S4 both 3101-2046 switch DPDT, slide
T1 6033A 5080-1978 transformer, power
6038A 06038-80090 transformer, power
T2 both 9170-1264 core, magnetic (used with primary wire 06023-80004)
T3 both 9100-4864 transformer, bias
T4 both 5080-1984 choke, line 2mH
TP1,2 both 1251-5613 connector, single contact
U1 both 1906 0006 rectifier bridge 400V 1A
VR1,2 6038A 1902-1377 diode-zener 6.19V 2%
W1,2 both 06023-80003 jumper, output 10 AWG
XA2P1 both 1251-8665 connector, 30-contact
XA2P2 both 1251-8667 connector, 20-contact
XA4P1,2 both 1251-8806 connector, DIN 32-contact

A1 Mechanical
both 1480-0552 pin, escutcheon (L1)
both 0380-1489 snap-in spacer
both 2110-0726 fuseholder, clip type (F2)
both 0360-2190 jumper, local sensing (2)
6038A 0360-1833 barrier block, 6-position
6033A 0360-2192 barrier block, 2-position
6033A 06023 00007 bus bar, negative
6033A 06023-00008 bus bar, positive

A2 6033A 06023-60023 Control Board Assembly

6038A 06038 60023 Control Board Assembly
C1 both 0160-5469 cap 1µF 10% 50V
C2 both 0160-5422 cap 0.047µF 20% 50V

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

C3 6033A 0160-4801 cap 100pF 5% 100V
6038A 0160-4812 cap 220pF 5%
C7 both 0160-5422 cap 0.047µF 20% 50V
C8 both 0160-4812 cap 220pF 5% 100V
C9 both 0160-5377 cap 2.2µF 10% 63V
C10,11 both 0160-5469 cap 1µF 10% 50V
C12,13 both 0160-5422 cap 0.047µF 20% 50V
C14 both 0180-0291 cap 1µF 10% 35V
C15 both 0180-1731 cap 4.7µF 10% 50V
C16,17 both 0180-0230 cap 1µF 20% 50V
C18,19 both 0180-0291 cap lµF 10% 35V
C20 both 0180-2624 cap 2000µF +75-25% 10V
C21 both 0160-5098 cap 0.22µF 10% 50V
C22 both 0160-4832 cap 0.01µF 10% 100V
C23 both 0180-3407 cap 2200µF +50-10% 35V
C24 both 0160-5098 cap 0.22µF 10% 50V
C25 both 0160-4833 cap 0.022µF 10% 100V
C26 both 0160-0154 cap 2200pF 10% 200V
C27,28 both 0160-5422 cap 0.047µF 20% 50V
C29 6033A 0160-4808 cap 470pF 5% 100V
6038A 0160-4812 cap 220pF 5% 100V
C30 both 0160-4830 cap 2200pF 10% 100V
C31 6033A 0160-4808 cap 470pF 5% 100V
6038A 0160-4801 cap 100pF 5% 100V
C32 both 0160-4801 cap 100pF 5% 100V
C33-35 both 0160-5422 cap 0.047µF 20% 50V
C36 6033A 0160-5422 cap 0.047µF 20% 50V
6038A 0160-4833 cap 0.022µF 10% 100V
C37 both 0160-5422 cap 0.047µF 20% 50V
C38 6033A 0160-4801 cap 100pF 5% 100V
6038A 0160-4803 cap 68pF 5% 100V
C39,40 both 0160-5422 cap 0.047µF 20% 50V
C41 both 0160-4835 cap 0.1µF 10% 50V
C42 both 0160-4805 cap 47pF 5% 100V
C43 both 0160-5422 cap 0.047µF 20% 50V
C44 both 0160-4805 cap 47pF 5% 100V
C45 6033A 0160-4808 cap 470pF 5% 100V
6038A 0160-4810 cap 330pF 5% 100V
C46 both 0160-4807 cap 33pF 5% 100V
C47 both 0160-4822 cap 1000pF 5% 100V
C48 both 0160-5422 cap 0.047µF 20% 50V
C49 6033A 0160-5644 cap 0.033µF 10% 100V
6038A 0160-4833 cap 0.022µF 10% 100V
C50 6033A 0160-0167 cap 0.082µF 10% 200V
6038A 0160-0168 cap 0.1µF 10% 200V
C51 both 0160-4801 cap 100pF 5% 100V
C52,53 both 0160-4831 cap 4700pF 10% 100V
C54 both 0160-5422 cap 0.047µF 20% 50V
C55,56 both 0160-4801 cap 100pF 5% 100V

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

C57,58 both 0160-5422 cap 0.047µF 20% 50V
C59 both 0160-4812 cap 220pF 5% 100V
C60 both 0160-5422 cap 0.047pF 20% 50V
C61 both 0160-4812 cap 220pF 5% 100V
C62 both 0160-5422 cap 0.047pF 20% 50V
C63 both 0180-0116 cap 6.8µF 10% 35V
C64,65 both 0160-5422 cap 0.047µF 20% 50V
C66 both 0180-0376 cap 0.47µF 10% 35V
C67,68 both 0160-4812 cap 220pF 5% 100V
C69 both 0160-4832 cap 0.01µF 10% 100V
C70 both 0180-1980 cap 1µF 5% 35V
C71 both 0160-5422 cap 0.047pF 20% 50V
C72 6038A 0160-5422 cap 0.047pF 20% 50V
CR1,2 both 1901-0033 diode-gen purp 180V 200mA
CR3 both 1901-0050 diode-switching 80V 200mA
CR5-7 both 1901-0033 diode-gen purp 180V 200mA
CR8-10 both 1901-0050 diode-switching 80V 200mA
CR11 both 1901-0992 diode-power rectifier 40V 3A
CR12-16 both 1901-0033 diode-gen purp 180V 200mA
CR18 both 1901-0033 diode-gen purp 180V 200mA
CR19 both 1901-0050 diode-switching 80V 200mA
CR20 both 1901-0033 diode-gen purp 180V 200mA
CR21-30 both 1901-0050 diode-switching 80V 200mA
J1,2 both 1251-8417 connector, 16-contact
L1 both 06023-80090 choke, bias, 820µH
P1 both 1251-8664 connector, 30-contact
P2 both 1251-8666 connector, 20-contact
Q1,2 both 1855-0413 transistor, J-FET P-chan 2N5116
Q3 both 1854-0635 transistor, NPN SI D44H5
Q4 both 1853-0012 transistor, PNP SI 2N2904A
Q5 both 1854-0823 transistor, NPN SI
Q6 both 1858-0023 transistor array CA3081E
Q7 6038A 1854-0087 transistor, NPN SI
R1 both 0683-5125 res 5.1K 1/2W
R2 6033A 0757-4715 res 470 1% 1/8W
6038A 0757-0419 res 681 1% 1/8W
R3 6033A 0698-6329 res 845 1% 1/8W
6038A 0698-6393 res 585 1% 1/8W
R4 both 0683-1035 res 10K 5% 1/4W
R5 6033A 0699-7880 res 28.7K 1% 1/8W
6038A 0699-0774 res 6.65K 1% 1/8W
R6 both 0683-5125 res 5.1k 5% 1/4W
R7 both 0683-4745 res 470K 5% 1/4W
R8 both 2100-3353 trimmer 20K side adjust
R9 6033A 2100-3350 trimmer 200 side adjust
6038A 2100-3993 trimmer 200 side adjust
R10 6033A 0757-5625 res 5.6K 1% 1/8W
6038A 0757-0427 res 1.5K 1% 1/8W
R11 6033A 0698-3136 res 17.8K 1%
6038A 0683-1025 res 1K 5% 1/4W

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

R12 both 0683-1025 res 1K 5% 1/4W
R13 both 0683-2735 res 27K 5% 1/4W
R14 both 0686-5125 res 5.1K 1/2W
R15 both 0683-2015 res 200 5% 1/4W
R16 6033A 0683-3355 res 3.3M 5% 1/4W
6038A 0683-2255 res 2.2M 5% 1/4W
R17 6033A 0683-6835 res 68k 5% 1/8W
6038A 0757-0289 res 13.3K 1% 1/8W
R18 6033A 0683-3035 res 30K 5% 1/4W
6038A 0757-0449 res 20K 1% 1/8W
R19 6033A 0683-4735 res 47K 5% 1/4W
6038A 0757-0449 res 20K 1% 1/8W
R20 both 0683-1035 res 10K 5% 1/4W
R21 6033A 2100-3350 trimmer 200 side adjust
6038A 2100-3273 trimmer 2K side adjust
R22 both 2100-3353 trimmer 20k side adjust
R23 both 2100-3273 trimmer 2K side adjust
R24 both 2100-3350 trimmer 200 side adjust
R25 both 2100-3207 trimmer 5K side adjust
R26 both 0683-1045 res 100K 5% 1/4W
R27 both 0698-6322 res 4K 0.1% 1/8W
R28 both 0683-1045 res 100K 5% 1/4W
R29 both 0698-4416 res 169 1% 1/8W
R30 both 0683-7545 res 750K 5% 1/4W
R31 both 0698-6322 res 4K 0.1% 1/8W
R32 both 0698-4416 res 169 1% 1/8W
R33 both 0698-4447 res 280 1% 1/8W
R34 both 0757-0404 res 130 1% 1/8W
R35 both 0698-4608 res 806 1% 1/8W
R36 both 0757-0438 res 5.11K 1% 1/8W
R37,38 both 0683-1035 res 10K 5% 1/4W
R39 both 0686-2005 res 20 5% 1/2W
R40 both 0683-1005 res 10 5% 1/4W
R41,42 both 0686-6215 res 620 5% 1/2W
R43 both 0683-1515 res 150 5% 1/4W
R44 both 0757-0434 res 3.65K 1% 1/8W
R45 both 0757-0442 res 10k 1% 1/8W
R46,47 both 0757-0283 res 2K 1% 1/8W
R48,49 both 0686-1315 res 130 5% 1/2W
R50 both 0811-3174 res 0.07 5% 5W
R51 both 0698-6076 res 39K 1% 1/8W
R52 both 0757-0280 res 1K 1% 1/8W
R53 both 0698-4121 res 11.3K 1% 1/8W
R54 both 0683-2015 res 200 5% 1/4W
R55 6033A 0683-5655 res 5.6M 5% 1/4W
6038A 0683-1055 res 1M 5% 1/4W
R56 6033A 0757-0408 res 243 1/4W
6038A 0757-0269 res 270 1/4W
R57 6033A 0683-1325 res 1.3K 5% 1/4W
6038A 0683-2015 res 200 5% 1/4W

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

R58 both 0683-1045 res 100K 5% 1/4W
R59 both 0698-8816 res 2.15 1% 1/8W
R60 both 0757-0199 res 21.5K 1% 1/8W
R61 6033A 0699-0059 res 5K 0.1% 1/8W
6038A 0698-6360 res 10K 0.1% 1/8W
R62 6033A 0698-3432 res 26.1 1% 1/8 W
6038A 8159-0005 wire, tinned copper, AWG 22
R63 6033A 0699-0059 res 5K 0.1% 1/8W
6038A 0698-6360 res 10K 0.1% 1/8W
R64 both 0683-5125 res 5.1K 5% 1/4W
R65 6033A 0699-0118 res 20K 0.1% 0.1W
6038A 0699-1210 res 80K 0.1% 0.1W
R66 6033A 0699-0118 res 20K 0.1% 0.1W
6038A 0699-1211 res 95K 0.1% 0.1W
R67,68 both 0686-5125 res 5.1K 5% 1/2W
R69 both 0683-2225 res 2.2K 5% 1/4W
R70 both 0683-2015 res 200 5% 1/4W
R71 6033A 0683-2735 res 27K 1% 1/8W
6038A 0698-5089 res 33K 1% 1/8W
R72 6033A 0757-0465 res 100K 1% 1/8W
6038A 0757-0470 res 162K 1% 1/8W
R73,74 6033A 0683-2035 res 20K 1% 1/8W
6038A 0757-0452 res 27.4K 1% 1/8W
R75 both 0683-7545 res 750K 5% 1/4W
R76 6033A 0683-4735 res 47K 1% 1/8W
6038A 0757-0446 res 15K 1% 1/8W
R77 6033A 0683-7545 res 750K 1% 1/8W
6038A 0757-0469 res 150K 1% 1/8W
R78 6033A 0757-0415 res 475 1% 1/8W
6038A 0698-4014 res 787 1% 1/8W
R79 both 0698-6983 res 20.4K 0.1% 1/8W
R80 both 0698-6320 res 5K 0.1% 1/8W
R81 both 0757-0459 res 56.2K 1% 1/8W
R82 both 0683-3325 res 3.3K 5% 1/4W
R83 both 0757-0270 res 249K 1% 1/8W
R84 6033A 0683-5125 res 5.1K 1% 1/8W
6038A 0757-0442 res 10K 1% 1/8W
R85 both 0698-3450 res 42.2K 1% 1/8W
R86 both 0757-0452 res 27.4K 1% 1/8W
R87 both 0683-2715 res 270 5% 1/8W
R88,89 both 0683-2225 res 2.2K 5% 1/4W
R90 both 0683-2715 res 270 5% 1/4W
R91 both 0683-2225 res 2.2K 5% 1/4W
R92 both 0683-2015 res 200 5% 1/4W
R93 both 0683-5125 res 5.1K 5% 1/4W
R94 both 0683-1035 res 10K 5% 1/4W
R95 both 0757-0472 res 200K 1% 1/8W
R96 6033A 0698-3572 res 60.4K 1% 1/8W
6038A 0757-0455 res 36.5K 1% 1/8W

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

R97 both 0683-5125 res 5.1K 5% 1/4W
R98 both 0683-2735 res 27K 5% 1/4W
R99 both 0683-1035 res 10K 5% 1/4W
R100,101 both 1810-0365 network sip 2.2K X5
R102,103 both 0757-0449 res 20K 1% 1/8W
R104 both 0757-0280 res 1K 1% 1/8W
R105 both 0698-3430 res 21.5K 1% 1/8W
R106 both 0698-3449 res 28.7K 1% 1/8W
R107 both 0698-3153 res 3.38K 1% 1/8W
R108 both 0683-2035 res 20K 5% 1/4W
R109 both 0683-2225 res 2.2K 5% 1/4W
R110 both 0683-4725 res 4.7K 5% 1/4W
R111 both 0683-2025 res 2K 5% 1/4W
R112 both 0683-1125 res 1.1K 5% 1/4W
R113 both 0757-0442 res 10K 1% 1/8W
R114 both 0757-0424 res 1.1K 1% 1/8W
R115 both 0683-1015 res 100 5% 1/4W
R116 both 0698-3498 res 8.66K 1% 1/8W
R117 both 0757-0438 res 5.11K 1% 1/8W
R118 both 1810-0365 network sip 2.2K X5
R119 both 0757-0288 res 9.09 1% 1/8W
R120 both 0683-1005 res 10 5% 1/4W
R121 both 0757-0442 res 10K 1% 1/8W
R122 both 0683-5135 res 51K 5% 1/4W
R123-126 both 0683-4725 res 4.7K 5% 1/4W
R127 both 0683-1855 res 1.8M 5% 1/4W
R128 both 0683-6835 res 68K 5% 1/4W
R129 both 0757-0439 res 6.8K 1% 1/8W
R130 both 0683-1055 res 1M 5% 1/4W
R131 both 0683-3335 res 33K 5% 1/4W
R132 both 0683-2225 res 2.2K 5% 1/4W
R133 both 0683-2735 res 27K 5% 1/4W
R134 both 0757-0466 res 110K 1% 1/8W
R135,136 both 0757-0442 res 10K 1% 1/8W
R137 both 0698-3455 res 261K 1% 1/8W
R138 both 0683-2045 res 200K 5% 1/8W
R139 both 0757-0442 res 10K 1% 1/8W
R140 both 0698-3160 res 31.6K 1% 1/8W
R141 both 0683-1025 res 1K 5% 1/4W
R142 both 0683-2225 res 2.2K 5% 1/4W
R143 both 0683-1045 res 100K 5% 1/4W
R144 both 0683-4725 res 4.7K 5% 1/4W
R145 both 0683-4715 res 470 5% 1/4W
R146,147 both 0683-1125 res 1.1K 5% 1/4W
R148 both 0683-3925 res 3.9K 5% 1/4W
R149 both 1810-0365 network sip 2.2K X5
R150,151 both 0683-1815 res 180 5% 1/4W
R152 both 0683-1025 res 1K 5% 1/4W
R153 6038A 0683-1035 res 10K 5% 1/4W
R155 6038A 0683-1005 res 10 5% 1/4W

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

R156-158 6038A 0683-1005 res 10 5% 1/4W
S1 both 3101-2097 switch 6-lA slide
U1 both 1826-0493 IC op amp Lo-bias Hi-impedance
U2 both 1826-0346 IC op amp dual general purpose
U3 both 1826-0161 IC op amp quad general purpose
U4 both 1826-0527 IC voltage regulator 1.2/37V
U5 both 1826-0544 IC voltage reference 2.5V
U6 both 1826-0428 IC voltage regulator 1/40V
U7,8 both 1826-0493 IC op amp Lo-bias Hi-impedance
U9 both 1826-0544 IC voltage reference 2.5V
U10 both 1826-0161 IC op amp quad
U11 both 1820-1209 IC buffer quad NAND
U12 both 1826-0393 IC voltage regulator 1.2/37V
U13 both 1820-1112 IC flip-flop D-type
U14 both 1826-0138 IC comparator quad
U15 both 1820-1437 IC multivibrator monostable dual
U16 both 1826-0065 IC comparator precision
U17 both 1820-1246 IC gate quad AND
U18 both 1820-0935 IC counter binary CMOS
U19 both 1820-1205 IC gate dual AND
U20 both 1826-0138 IC comparator quad
U21 both 1826-0065 IC comparator precision
U22 both 1820-2096 IC counter binary dual
VR1,2 both 1902-0018 diode-zener 11.7V 5%
VR3 both 1902-0777 diode-zener 6.2V 5%
VR4 both 1902-3110 diode-zener 5.9V 2%
VR5 both 1902-0575 diode-zener 6.5V 2%
W1-3 both 7175-0057 jumper wire, AWG 22
Y1 both 0960-0586 resonator 320KHz

A2 Mechanical
both 5060-2942 heatsink (Q2, U15,16)
both 1200-0181 insulator (Q4)
both 1200-0485 socket (S1)
both 0360-2195 terminal block, 6-position
both 1531-0309 clevis, tapped

A3 both 06033-60020 Front Panel Board

C1,2 both 0180-0374 cap 10µF 10% 20V
C3-14 both 0160-5422 cap 0.047µF 20% 50V
DS1-8 both 1990-0985 numeric display, 8-character
DS9, 10 both 1990-0835 LED
DS11-16 both 1990-0831 LED
DS17-23 both 1990-0835 LED
G1 both 06033-60008 pulse generator
J1 both 1251-8417 connector, 16-contact
J2,3 both 1251-8675 connector, 5-contact
L1 both 9100-1618 inductor 5.6µH 10%
R1-58 both 0683-4715 res 470 5% 1/4W

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

R59 both 2100-1775 trimmer 5K top adjust
R60 both 0683-1015 res 100 5% 1/4W
R61,62 both 1810-0272 network sip 330 X9
R63 both 1810-1231 network smd 100 X8
S2-5 both 5060-9436 switch, pushbutton
U1-10 both 1820-1433 IC shift register, 8-bit
U11 both 1820-1975 IC shift register, 8-bit
U12 both 1820-1112 IC flip flop, D-type
U13,14 both 1820-1216 IC decoder, 3-to-8 line
U15 both 1820-1433 IC shift register, 8-bit
U16 both 1820-1197 IC gate quad NAND
U17 both 1820-1199 IC inverter, HEX

A3 Mechanical
both 4040-1615 standoff, LED (DS9-23)

A4 6033A 06023-60022 Power Mesh Board

6038A 06038-60022 Power Mesh Board
C1 both 0160-5891 cap 0.47µF 10% 800Vdc
C2 both 0160-5422 cap 0.047µF 20% 50Vdc
C5,6 both 0160-4960 cap 2200pF 10% 1.6KV
C7 both 0180-0155 cap 2.2µF 20% 20V
C8 both 0160-0127 cap 1µF 20% 25V
C9 both 0180-2780 cap 470µF 10% 16V
C10 both 0160-4834 cap 0.047µF 10% 100V
C11,12 both 0160-4835 cap 0.1µF 10% 50V
C13 6033A 0160-0161 cap 0.01µF 10% 200V
6038A 0160-5022 cap 2200pF 10% 600Vac
CR1-4 both 1901-0050 diode-switching 80V 200mA
CR5,6 both 1901-1065 diode-power rectifier 400V 1A
CR7 6033A 1901-1127 diode-power rectifier 150V 70A
6038A 1901-0887 diode-power rectifier 300V 50A
CR10,11 both 1901-0050 diode-switching 80V 200mA
CR13,14 both 1901-1087 diode-power rectifier 600V 3A
F1,2 both 2110-0671 fuse, 1/8A 125V
F3 6033A 2110-0546 fuse, 5A 125V
6038A 2110-0688 fuse, 3A
L3 both 06024-80096 inductor, 3A
L4 6033A 06023-80005 core, ferrite 5µH
6038A 06024-80097 inductor, 12A
P1,2 both 1251-8807 connector DIN 32-contact
Q1,2 both 1854-0477 transistor, NPN SI 2N222A
Q3,4 both 1855-0916 transistor, MOSFET N-channel
Q6 6033A 1854-0264 transistor, NPN SI
6038A 1854-1017 transistor, NPN SI
Q7 both 1855-0549 transistor, PFET
R1,2 both 0686-0275 res 2.7 5% 1/2W
R3 both 0683-3915 res 390 5% 1/4W
R4 both 0683-1015 res 100 5% 1/4W

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

R5 both 0683-4705 res 47 5% 1/4W
R6 both 0683-1045 res 100K 5% 1/4W
R7 both 0811-1857 res 400 5% 5W
R8 both 0698-3601 res 10 5% 2W
R9 both 0683-3915 res 390 5% 1/4W
R10 both 0683-1015 res 100 5% 1/4W
R11 both 0683-4705 res 47 5% 1/4W
R12 both 0683-1045 res 100K 5% 1/4W
R13 both 0811-1857 res 400 5% 5W
R14 both 0698-3601 res 10 5% 2W
R15 both 0757-0403 res 121 1% 1/8W
R16 both 0683-3305 res 33 5% 1/4W
R17 both 0683-1025 res lK 5% 1/4W
R18 both 0683-0475 res 4.7 5% 1/4W
R19 both 0683-2025 res 2K 5% 1/4W
R20 both 0683-0275 res 2.7 5% 1/4W
R21,22 both 0683-0475 res 4.7 5% 1/4W
R23 both 0683-2725 res 2.7K 5% 1/4W
R24 6033A 0757-0464 res 90.9K 1% 1/8W
6038A 0757-0476 res 301K 1% 1/8W
R25 6033A 0686-1005 res 10 5% 1/2W
6038A 0686-3005 res 30 5% 1/2W
R26 6033A 0811-2490 res 0.1 3% 5W
6038A 0811-2994 res 0.27 3% 5W
R27 both 0698-3225 res 1.43K 1% 1/8W
R28 both 0757-0279 res 3.16K 1% 1/8W
R29 both 0698-3159 res 26.1K 1%1/8W
R30 both 0698-3202 res 1.74K 1% 1/8W
R31 both 0698-4046 res 732 1%
R32 both 0757-0442 res 10K 1% 1/8W
R33 6033A 0698-3601 res 10 5% 2W
6038A 0698-3628 res 220 5% 2W
R34 both 0698-4484 res 19.1K 1% 1/8W
R35,36 both 0683-3305 res 33 5% 1/4W
R37 both 0683-3325 res 3.3K 5% 1/4W
R38 6038A 0757-0465 res 100K 1% 1/8W
R39 both 0683-1055 res lM 5% 1/4W
T1,2 both 5080-1983 transformer, FET driver
T3 both 1900-4350 transformer, current
TS1 both 3103-0116 thermal switch +100 C
TP14 both 1251-0646 connector, contact
U1,2 both 1820-1050 IC driver dual NOR
U3 both 1826-0346 IC op amp dual general purpose
U4 both 1826-0393 IC voltage regulator 1.2/37V
VR2 both 1902-3002 diode-zener 2.37V 5%
VR3 both 1902-0057 diode-zener 6.49V 5%
VR4 both 1902-0575 diode-zener 6.50V 2%

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

A4 Mechanical
both 1205-0919 heatsink (Q3,4)
both 5060-2942 heatsink (Q7)
both 06023-20001 heatsink (CR7)
both 1531-0309 clevis, tapped
A8 both 5063-3463 HP-IB/PSI Board
C1 both 0160-5422 cap 0.047µF 20% 50V
C2,3 both 0160-4807 cap 33pF 5% 100V
C4 both 0160-5422 cap 0.047µF 20% 50V
C5 both 0160-4822 cap 1000pF 100V
C6 both 0180-0197 cap 2.2µF 10% 20V
C7,8 both 0160-4807 cap 33pF 5% 100V
C9 both 0160-5422 cap 0.047µF 20% 50V
C10 both 0160-4801 cap 100pF 5% 100V
C11,12 both 0160-5422 cap 0 047µF 20% 50V
C13 both 0160-4801 cap 100pF 5% 100V
C14 both 0160-4832 cap 0.01µF 10% 50V
C15 both 0160-5422 cap 0.047µF 20% 50V
C16 both 0160-4801 cap 100pF 5% 100V
C22 both 0180-3798 cap 4700µF 25V
C23 both 0180-4136 cap 10µF 10% 20V
C24 both 0180-0393 cap 39µF 10% 10V
C25,26 both 0160-5422 cap 0.047µF 20% 50V
C27 both 0180-0374 cap 10µ.F 10% 20V
C28-31 both 0160-5469 cap 1µF 10% 50V
C32-37 both 0160-5422 cap 0.047µF 20% 50V
C38 both 0180-0116 cap 6.8µF 10% 35V
C39,40 both 0160-5422 cap 0.047µF 20% 50V
C41,42 both 0160-4820 cap 1800pF 5% 100V
C43-47 both 0160-5422 cap 0.047µF 20% 50V
C48 both 0180-0116 cap 6.8µF 10% 35V
C49-51 both 0160-5422 cap 0.047µF 20% 50V
C52 both 0160-4822 cap 1000pF 100V
C53-58 both 0160-5422 cap 0.047µF 20% 50V
C59,60 both 0160-4822 cap 1000pF 100V
C61 both 0160-4830 cap 2200pF 10% 250V
C62,63 both 0160-4807 cap 33pF 5% 100V
C64 both 0160-5422 cap 0.047µF 20% 50V
C65 both 0180-0393 cap 39µF 10% 10V
C66 both 0160-5422 cap 0.047µF 20% 50V
C67-70 both 0160-4832 cap 0.01µF 10% 50V
C71,73 both 0160-4830 cap 2200pF 10% 250V
C142 both 0160-4801 cap 100pF 5% 100V
C143,144 both 0160-5422 cap 0.047µF 20% 50V
D8,9 both 1901-0731 diode-power rectifier
D13-17 both 1901-1098 diode-switching
D20,21 both 1901-1080 diode-1N5817
D22 both 1901-1098 diode-switching
F1,2 both 2110-0712 fuse, 4A 125V

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

J1,2 both 1251-7330 telephone jacks
J3 both 1200-0485 right angle socket
J4 both 1252-0268 HP-IB connector
J5 both 1251-4926 connector 8-contact
J6 both 1251-4927 connector 16-contact
J7,8 both 1251-8417 connector 16-contact
J9 both 12514927 connector 16-contact
J10 both 1251-5384 connector 3-contact
L1 both 9170-1680 choke
L2-4 both 9170-1454 core-shield bead
Q1, 4 both 1853-0089 transistor 2N4917
R1 both 0757-0457 res 47.5 1% 1/8W
R2 both 0698-3155 res 4.64K 1% 1/8W
R3 both 0757-0442 res 10K 1% 1/8W
R4 both 0698-3155 res 4.64K 1% 1/8W
R5 both 0683-1065 res 10M 5% 1/4W
R6 both 0698-4037 res 46.4 1% 1/8W
R7 both 0698-3155 res 4.64K 1% 1/8W
R8-11 both 0757-0401 res 100 1% 1/8W
R12 both 0698-3155 res 4.64K 1% 1/8W
R14 both 0698-0082 res 464 1% 1/8W
R15-17 both 0698-4037 res 46.4 1% 1/8W
R18 both 0757-0280 res 1K 1% 1/8W
R19 both 0698-8827 res 1M 1% 1/8W
R20-22 both 0698-3155 res 4.64K 1% 1/8W
R23 both 0698-0082 res 464 1% 1/8W
R24,26 both 0698-3156 res 14.7K 1% 1/8W
R28 both 0699-0059 res 5K 0.1% 1/10W
R29 both 2100-3353 trimmer 20K, side adjust
R30 both 0699-0642 res 10K 0.1% 1/10W
R32 both 0757-0457 res 47.5K 1% 1/8W
R33 both 0698-6360 res 10K 0.1% 1/8W
R34 both 0757-0401 res 100 1% 1/8W
R35 both 0699-0059 res 5K 0.1% 1/10W
R36 both 0757-0316 res 42.2 1% 1/8W
R37 both 0699-0642 res 10K 0.1% 1/10W
R39 both 0757-0270 res 249K 1% 1/8W
R40 both 2100-3353 trimmer 20K, side adjust
R41 both 0757-0401 res 100 1% 1/8W
R42 both 0757-0411 res 332 1% 1/8W
R43 both 0699-0059 res 5K 0.1% 1/l0W
R44 both 0757-0316 res 42.2 1% 1/8W
R45 both 0699-0642 res 10K 0.1% 1/10W
R46 both 0757-0411 res 332 1% 1/8W
R48 both 0757-0457 res 47.5K 1% 1/8W
R49 both 0698-6360 res 10K 0.1% 1/8W
R50 both 0757-0401 res 100 1% 1/8
R51 both 2100-3353 trimmer 20K, side adjust
R52 both 0698-3156 res 14.7K 1% 1/8W

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

R55,58 both 2100-3732 trimmer 500, top adjust
R59,60 both 0698-3558 res 4.02K 1% 1/8W
R61 both 2100-3732 trimmer 500, top adjust
R62-64 both 0698-3558 res 4.02K 1% 1/8W
R65 both 0757-0280 res 1K 1% 1/8W
R66 both 0698-3558 res 4.02K 1% 1/8W
R67 both 0698-6320 res 5K 0.1% 1/8W
R68 both 0757-0400 res 90.9 1% 1/8W
R69 both 0698-6320 res 5K 0.1% 1/8W
R70 both 0757-0400 res 90.9 1% 1/8W
R71 both 0698-6320 res 5K 0.1% 1/8W
R72 both 0757-0400 res 90.9 1% 1/8W
R73 both 0757-0451 res 24.3k 1% 1/8W
R74 both 0757-0199 res 21.5K 1% 1/8W
R75 both 2100-3273 trimmer 2K, side adjust
R76 both 0698-3455 res 261K 1% 1/8W
R78 both 0698-3156 res 14.7K 1% 1/8W
R79,80 both 8159-0005 res 0 ohm
R82 both 0698-0082 res 464 1% 1/8W
R83-88 both 0698-3155 res 4.64K 1% 1/8W
R89 both 0757-0280 res 1K 1% 1/8W
R90,98,99 both 0698-3155 res 4.64K 1% 1/8W
R101 both 0698-6360 res 10K 0.1% 1/8W
R102 both 0698-3558 res 4.02K 1% 1/8W
R103 both 0698-3455 res 261K 1% 1/8W
R106 both 1810-0206 network, sip 10K X7
R109,110 both 0698-3155 res 4.64K 1% 1/8W
R111 both 0757-0316 res 42.2 1% 1/8W
R112 both 1810-0305 network, sip
S1 both 3101-1973 HP-IB switch
TB1 both 0360-2312 terminal block 4-contact
U1 both 1826-0468 IC MC3423P1 0V-level detect
U2 both 5080-2157 IC GAL programmed
U4 both 1820-8773 IC 80C51 microprocessor
U5 both 1826-1369 IC LT1021 voltage regulator 10V
U6 both 5080-2624 IC EPROM AM27512
U7 both 1826-2187 IC converter PM-7545
U8 both 1818-4134 IC RAM MCM6164C55
U9 both 1826-2187 IC converter PM-7545
U11 both 1826-2187 IC converter PM-7545
U12 both 1820-3210 IC UART MC68B50P
U13 both 1990-0543 IC opto-isolator
U14 both 1821-1479 IC 80C196 microprocessor
U16 both 1820-2724 IC latch 74ALS573
U19 both 1826-0161 IC LM324N quad op amp
U20 both 1826-0609 IC 8-input multiplexer
U24 both 1826-1475 IC LT1011 comparator
U25 both 1826-1896 IC LT1001 op amp
U28 both 1990-1387 IC opto-isolator

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

U31 both 1820-6789 IC 75176B RS485 driver
U32 both 1990-1387 IC opto-isolator
U33 both 1826-0536 IC LM340AK-5 voltage regulator 5V
U35 both 5080-2625 IC GAL programmed
U36 both 5080-2158 IC GAL programmed
U37 both 1820-4185 IC DS3658N interface
U64-69 both 1826-1896 IC LT1001 op amp
U70 both 1818-4932 IC EEPROM NMC9346
U115 both 1820-6045 IC SN75ALS61610
U116 both 1820-6170 IC SN75ALS6160
U117 all 1821-1740 IC 9914 talker/listener
VR2 both 1902-3172 diode-zener 11V
VR3,4 both 1902-0049 diode-zener 6.19V
VR6,7,8 both 1902-0766 diode-zener 18.2V
Y1,2 both 0410-2109 oscillator 12MHz

A8 Mechanical
both 1205-0564 heat sink (U33)
both 5001-6732 HP-IB mounting plate

Chassis Electrical
B1 both 3160-0343 fan
S1 both 3101-0402 switch, DPST (on/off)
FL1 both 9135-0223 ac line filter
F1 both 2110-0383 fuse, 8A 250V
W1 both 8120-4355 cable, ribbon (A3 to A8)
W2 both 8120-4352 cable, 3-pin (A1 to A8)
W3 both 8120-4351 cable, 5-pin (A1 to A3)
W5,6 both 8120-4356 cable, ribbon (A2 to A8)

Chassis
Mechanical
both 06023-00016 chassis
both 5021-8417 front frame casting
both 06033-00010 front sub-panel
6033A 06033-00013 front panel, screened
6038A 06038-00015 front panel, screened
both 06023-00024 rear panel
both 1510-0044 binding post (rear panel ground)
both 2110-0564 fuseholder body
both 2110-0565 fuseholder cap
both 2110-0569 fuseholder nut
both 3160-0309 finger guard (fan)
both 06023-00023 bracket, upper (lettered)
both 0403-0282 bumper feet (on upper bracket)
both 06033-00002 bracket, lower (A8 board)
both 5041-8803 top trim strip
both 5001-0540 side trim strip (2)
both 01650-47401 knob (RPG adjust)

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 Table 5-3. Replaceable Parts List (continued)

Ref. Desig. HP Model HP Part Number Description

both 5041-0309 plain key cap (4)
both 5041-2089 lettered key cap (LCL)
both 7120-1254 LOGO
both 4040-1954 display window
both 06023-00020 cover, top
both 06023-00022 cover, bottom
both 06023-00009 cover, terminal block
6033A 0360-2191 cover, dc output
6038A 1540-1626 cover, dc output
both 5062-3703 strap handle
both 5041-8819 handle retainer, front
both 5041-8820 handle retainer, back
both 5041-8801 foot (4)

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 6
Component Location and Circuit Diagrams

This chapter contains component location diagrams, schematics, and other drawings useful for maintenance of the power
supply. Included in this section are:

a. Component location illustrations (Figures 6-1 through 6-6), showing the physical location and reference designators of
almost all electrical parts. (Components located on the rear panel are easily identified.)
b. Notes (Table 6-1) that apply to all schematic diagrams.
c. Schematic diagrams (Figures 6-7 through 6-9).

AC line voltage is present on the A1 Main Board Assembly whenever the power cord is connected to an ac
power source.

Table 6-1. Schematic Diagram Notes

1. denotes front-panel marking.

2. denotes rear-panel marking.

3. Complete reference designator consists of component reference designator prefixed with assembly number (e.g.:
A2R14).

4. Resistor values are in ohms. Unless otherwise noted, resistors are either 1/4W, 5% or 1/8W, 1%. Parts list provides
power rating and tolerance for all resistors.

5. Unless otherwise noted, capacitor values are in microfarads.

6. Square p.c. pads indicate one of the following:

a. pin 1 of an integrated circuit.
b. the cathode of a diode or emitter of a transistor.
c. the positive end of a polarized capacitor.

7. Schematic components marked with an asterisk (*) indicate that different values are used in each model. Refer to the
parts list for the applicable values.

8. indicates multiple paths represented by only one line. Reference designators with pin
numbers indicate destination, or signal names identify individual paths. Numbers
indicate number of paths represented by the line.

9. Inter-board commons have letter identifications (e.g.: ); commons existing on a single assembly have number
identifications (e.g.: ).

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 Table 6-1. Schematic Diagram Notes (continued)

10. For single in-line resistor packages, pin 1 is marked with a dot. For integrated circuit packages, pin 1 is either marked
with a dot, or pin 1 is to the left (as viewed from top) of indentation on the integrated circuit package (except for A8U6
and A8U8).

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 Figure 6-1. Top View, Top Covers Removed

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 Figure 6-2. Main Board (A1) Component Location

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 Figure 6-3. Control Board (A2) Component Location

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 Figure 6-4. Front Panel Board (A3) Component Location

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 Figure 6-5. Power Mesh Board (A4) Component Location

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 Figure 6-6. HP-IB Board (A8) Component Location

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 A
l00 Vac Input Power Option 100

General Information

Description

Option 100 is a modification of HP 6033A/6038A power supplies that involves changing a resistor in the A2 OVP circuit,
recalibrating the supply, and changing the Front Panel. These changes allow the units to operate at a lower line voltage of 87
to 106 Vac, while operating on the same line frequency of 48 to 63 Hz. The reduced input voltage limits the output power to
150W and the output voltage from 0 to 17V for the HP6033A, and from 0 to 50V for the HP6038A, while retaining the
standard’s unit output current rating. Other specifications that change due to Option 100 include Programming Response
Time, Overvoltage Protection and Remote Analog Programming.

Scope of Appendix A

This appendix contains all the information necessary to support HP 6033A/6038A power supplies that are equipped with
Option 100. The appendix describes only the changes pertaining to Option 100 and how they affect the other portions of this
manual. Unless otherwise specified in Appendix A, all other portions of the manual apply to both the standard unit and the
Option 100 unit.

Suggestions for Using Appendix A

The Option 100 changes are listed sequentially, starting with Chapter 1 in the main body of the manual and working back
through Chapter 6. It is recommended that the user mark all the necessary changes directly into his manual. This will update
the manual for Option 100 and eliminate the need for constant referrals back to Appendix A.

Chapter 1 Manual Changes

On Page 9, in Scope change the output power from 200 to 150 watts.

Chapter 2 Manual Changes

On Page 16, in Constant Voltage Full Scale Calibration, step b, change VSET 20 to VSET (6033A).

On Page 17, in Constant Voltage Full Scale Calibration, step d,

change 20.0025V to 17.0025V ±600µV (6033A).
change 60.0075 to 50.0175V ± 1.52mV (6038A).

On Page 17, in Voltage Monitor and Remote Readback Full Scale Calibration step b, change VSET 60 to VSET 50
(6038A).

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 On Page 17, in Voltage Monitor and Remote Readback Full Scale Calibration step c,
change 5.000625V to 4.250625V ±100µV (6033A).
change 5.000625V to 4.168125V ±80µV (6038A).

On Page 17, in Voltage Monitor and Remote Readback Full Scale Calibration step f,
change 20V and 20.005V to 17.000 and 17.005V (6033A).
change 60V and 60.015V to 50.025V and 50.01V (6038A).

On Page 19, in Power Limit Calibration step d, change 10A to 9.2A (6033A)

On Page 19, in Power Limit Calibration step e,

change ISET 30.5 to ISET 27.5 (6033A).
change VSET 23 to VSET 21 (6038A).

On Page 21 in Voltage Programming and Readback Accuracy step g,

change VSET 20 to VSET17 (6033A).
change VSET 60 to VSET 50 (6038A).

On Page 22, in Voltage Programming and Readback Accuracy step h,

change 19.984 and 20.016 to 16.988 and 17.012 (6033A).
change 59.939 and 60.061 to 49.9375 and 50.0525 (6038A).

On Page 22 in Voltage Programming and Readback Accuracy step I,

change 0.02 to 0.018V (6033A).

On Page 22, in Load Effect (Load Regulation) step c,

change 7.0V to 6.25V (6033A).
change 20.0V to 15.0V (6038A).

On Page 22 in Load Effect (Load Regulation) step d,

change 29A to 25A (6033A).

On Page 22 in Load Effect (Load Regulation) step h,

change 0.0027V to 0.0026V (6033A).

On Page 23, in Source Effect (Line Regulation) step d,

change 20V to 17V (6033A).
change 60V to 50V (6038A).

On Page 23, in Source Effect (Line Regulation) step e,

change 10A to 9A (6033A).

On Page 23, in Source Effect (Line Regulation) step i,

change 0.003 to 0.0027 (6033A).
change 0.08 to 0.007 (6038A).
‘
On Pages 23, 25, in RMS Measurement Procedure and Peak Measurement step c,
change 7.0 to 6.25V (6033A).

On Pages 23, 25, in RMS Measurement Procedure and Peak Measurement step d,
change 29A to 25A (6033A).
On Page 25, in Load Transient Recovery Time and step c
change 6.7V to 5.0V (6033A).

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 On Page 26, in Current Programming and Readback Accuracy steps c and g,
change 20V to 17V (6033A).
change 60V to 50V (6038A).

On Page 27 in Load Effect (Load Regulation) steps c,

change 10A to 9A (6033A).

On Page 27 in Load Effect (Load Regulation) steps d,

change 20V to 17V (6033A).
change 60V to 50V (6038A).

On Page 27, in Source Effect (Line Regulation) step d,

change 30A to 25A (6033A).

On Page 27, in Source Effect (Line Regulation) step e,

change 7.0 to 6.25V (6033A).
change 20.0 to 15.0V (6038A).

On Page 27, in Source Effect (Line Regulation) step i,

change 90µV to 85µV (6033A).

On Page 28, in PARD Ripple and Noise step c,

change 29A to 25A (6033A).

On Page 28, Initialization, change step 2 as follows:

2. Turn the power on, and depending on your unit’s model number, send the following strings:

"EEINIT 6033
"EEPROM 10,4,17.500"
or
’’EEINIT 6038
"EEPROM 10,4,51.495"

Chapter 3 Manual Changes:

On Page 41, in Readback Multiplexer (U20), change Node U20-9,

from + 5V to + 4.25V (6033A).
from + 5V to + 4.167V (6038A).

On Page 48 in Main Troubleshooting and on Page 49 in Troubleshooting No-Out Failures step d, change 320Vdc to
250Vdc.

In Table 3-10 (page 52) under Symptoms,

change max voltage <20 to max voltage <17 (6033A).
change max voltage <60 to max voltage <50 (6038A).

On Page 54 in Troubleshooting AC-Turn-On Circuits, setup,

change 20V to 17V (6033A).

Chapter 4 Manual Changes:

On Page 65, change 5V to 4.25V (6033A); change 5V to 4.167V (6038A).

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 On page 68, change 200W to 150W.

Chapter 5 and 6 Manual Changes

On Page 76,
change A2 board from 06023-60023 to 06023-60123 (6033A).
change A2 board from 06038-60023 to 06038-60024 (6038A).

On Page 80,
change R78 from 475 to 1.43K, HP P/N 0698-3225 (6033A).
change R78 from 787 to 1.96K, HP P/N 0698-0083 (6038A).
Make these same changes on the schematic diagram, Figure 6-7.

On Page 82, add Option 100 label (A2 board) 9320-5540.

On Page 88,
change front panel from 06033-00013 to 06033-00012 (6033A).
change front panel from 06038-00015 to 06038-00014 (6038A).

On Page 89,
add line voltage label (rear panel) 06033-81004 (6033A).
add line voltage label (rear panel) 06023-81004 (6038A).

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 B
Blank Front Panel Option 001

Introduction

This appendix describes the blank front panel option (Option 001) for the power supply. Option 001 is designed for
applications in which front panel operation and monitoring are unnecessary. It has no front-panel controls and indicators
except for the LINE switch and OVP ADJUST control found on the standard unit, and a pilot light to indicate when ac input
power is turned on. All other characteristics of the standard are retained.

Except for references to front-panel controls and indicators, most of the information in the manual applies to Option 001
units. No attempt has been made in this appendix to change every reference to front-panel controls and indicators. In
general, information in this appendix replaces only those procedures whose modification may not be obvious to the user.
When reading the manual, the user can usually skip over references to front-panel controls and indicators other than the
LINE switch and OVP ADJUST control.

Troubleshooting

The major difference between troubleshooting an Option 001 unit and a standard power supply is that the front panel is not
available to help you isolate the problem to a specific section in the power supply. If you know which section of the supply
is defective, simply go to that section in the troubleshooting procedure and troubleshoot as described in Chapter 3.

To help you isolate the problem to a specific area of the supply, use the flowchart provided in this section.

If you cannot isolate the problem using the flowchart, you could replace the blank front panel of your supply with a standard
front panel and then troubleshoot the unit. Part numbers for front panel assemblies are provided in Chapter 5.

Chapter 2 Manual Changes:

On Page 19, Power Limit Calibration, change step f to read: Connect a DVM to control board test connector A2J3 pin 16
(CC). Observe the DVM while adjusting A2R25 (POWER LIMIT) clockwise. Stop adjusting as soon as test point A2J3-16
goes from high to low.

Note: You can also send an STS? query (or SCPI equivalent) in a looping program and monitor when the power
supply status changes to CC mode.

Under the Performance Tests section, any references to front panel control will have to be accomplished using HP-IB
commands. Use the following guidelines:

1. To set the voltage and current to specific values, use the VSET and ISET (or SCPI equivalent) commands.

2. If the procedure says to check the CC or CV LED’s, use an STS? query (or SCPI equivalent). A returned value of 1
indicates CV mode; a value of 2 indicates CC mode.

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 Chapter 3 Manual Changes:

Replace Figure 3-1 with the figure on the next page. SA Tables 3-5 through 3-7 do not apply to Option 001 units.

Chapter 5 and 6 Manual Changes:

On Page 83 under A3 Front Panel Board, the only part that applies to the Option 001 unit is R59, the OVP-adjust
potentiometer. Change R59 from 2100-1775 to 2100-4060.

On Page 86 under Chassis Electrical, add Neon Pilot Light, P/N 1450-0647. Also add OVP Cable (R59), P/N 06032-60004.
Under Chassis Mechanical, change screened front panel to:

06033-00011 (6033A)
06038-00013 (6038A)

On Figure 6-7, add the neon pilot light in series with R29, 33K, across pins 4 and 5 of transformer T3.

On Figure 6-9, the only part that applies to the Option 001 unit is R59, the OVP-adjust potentiometer.

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 Figure 3-1. Troubleshooting Isolation (option 001)

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 C
HP 6033A Test Record
Performance Test Record - HP 6033A POWER SUPPLY (Page 1 of 2)

Test Facility:

__________________________________________ Report No.__________________________________________

__________________________________________ Date_______________________________________________
__________________________________________ Customer___________________________________________
__________________________________________ Tested By___________________________________________

Model HP 6033A Ambient Temperature _______________________________°C

Serial No.__________________________________ Relative Humidity ___________________________________%
Options ___________________________________ Nominal Line Frequency ____________________Hz (nominal)
Firmware Revision___________________________

Special Notes:

____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________

Test Equipment Used

Description Model No. Trace No. Cal. Due Date

1. AC Source _______________ _____________________________ _________________

2. DC Voltmeter HP 3458A _____________________________ _________________
3. RMS Voltmeter HP 3400A _____________________________ _________________
4. Oscilloscope HP 54504A _____________________________ _________________
5. Electronic Load HP 6060A and _____________________________ _________________
HP 60502A
6. Current Probe _______________ _____________________________ _________________
7. Current Shunt Guildline _____________________________ _________________
9230/100
_______________ _______________ _____________________________ _________________
_______________ _______________ _____________________________ _________________
_______________ _______________ _____________________________ _________________
_______________ _______________ _____________________________ _________________
_______________ _______________ _____________________________ _________________

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 Performance Test Record - HP 6033A POWER SUPPLY (Page 2 of 2)

MODEL HP 6033A Report No.______________ Date_____________________

Page Test Description Minimum Spec. Results Maximum Measurement

No. * Spec. Uncertainty
Constant Voltage Tests

21 Voltage Programming
and Readback
Low Voltage (0.100V) 0.091 ________V 0.109 3µV
Front Panel Display VOUT - 0.011 ________V VOUT + 0.011 3µV
HP-IB Readback VOUT - 0.006 ________V VOUT + 0.006 3µV

High Voltage (20.00V) 19.984 ________V 20.016 300µV

Front Panel Display VOUT - 0.025 ________V VOUT + 0.025 300µV
HP-IB Readback VOUT - 0.020 ________V VOUT + 0.020 300µV

22 Load Effect (7.0V) VOUT - 0.0027 _______mV VOUT + 0.0027 20µV

22 Source Effect (20.00V) VOUT - 0.003 _______mV VOUT + 0.003 20µV

PARD (Ripple and Noise)

23 RMS 0 _______mV 0.003 450µV
23 Peak-to-Peak 0 _______mV 0.030 900µV
25 Transient Recovery 0 _______mV 0.050 6mV
(90% to 100% Full Load)
Constant Current Tests

26 Current Programming
and Readback

Low Current (1.000A) 0.9785 ________A 1.0210 400µA

Front Panel Display IOUT - 0.023 ________A IOUT + 0.023 400µA
HP-IB Readback IOUT - 0.028 ________A IOUT + 0.028 400µA
High Current (30.00A) 29.935 ________A 30.065 12mA
Front Panel Display IOUT - 0.155 ________A IOUT + 0.155 12mA
HP-IB Readback IOUT - 0.115 ________A IOUT + 0.115 12mA
27 Load Effect (10.0A) IOUT - 0.010 ________mA IOUT + 0.010 19µA

27 Source Effect (30.0A) IOUT - 0.009 ________mA IOUT + 0.009 19µA

27 PARD (Ripple and Noise) 0 ________mA 0.015 2µA

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 D
HP 6038A Test Record
Performance Test Record - HP 6038A POWER SUPPLY (Page 1 of 2)

Test Facility:

__________________________________________ Report No.__________________________________________

__________________________________________ Date_______________________________________________
__________________________________________ Customer___________________________________________
__________________________________________ Tested By___________________________________________

Model HP 6038A Ambient Temperature _______________________________°C

Serial No.__________________________________ Relative Humidity ___________________________________%
Options ___________________________________ Nominal Line Frequency ____________________Hz (nominal)
Firmware Revision___________________________

Special Notes:

____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________
____________________________________________________________________________________________

Test Equipment Used

Description Model No. Trace No. Cal. Due Date

1. AC Source _______________ _____________________________ _________________

2. DC Voltmeter HP 3458A _____________________________ _________________
3. RMS Voltmeter HP 3400A _____________________________ _________________
4. Oscilloscope HP 54504A _____________________________ _________________
5. Electronic Load HP 6060A and _____________________________ _________________
HP 60502A
6. Current Probe _______________ _____________________________ _________________
7. Current Shunt Guildline _____________________________ _________________
9230/15
_______________ _______________ _____________________________ _________________
_______________ _______________ _____________________________ _________________
_______________ _______________ _____________________________ _________________
_______________ _______________ _____________________________ _________________
_______________ _______________ _____________________________ _________________

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 Performance Test Record - HP 6038A POWER SUPPLY (Page 2 of 2)

MODEL HP 6038A Report No.______________ Date_____________________

Page Test Description Minimum Spec. Results Maximum Measurement

No. * Spec. Uncertainty
Constant Voltage Tests

21 Voltage Programming
and Readback
Low Voltage (0.090V) 0.050 ________V 0.130 3µV
Front Panel Display VOUT - 0.050 ________V VOUT + 0.050 3µV
HP-IB Readback VOUT - 0.050 ________V VOUT + 0.050 3µV

High Voltage (60.0V) 59.939 ________V 60.061 845µV

Front Panel Display VOUT - 0.092 ________V VOUT + 0.092 845µV
HP-IB Readback VOUT - 0.092 ________V VOUT + 0.092 845µV

22 Load Effect (20.00V) VOUT - 0.005 _______mV VOUT + 0.005 20µV

22 Source Effect (60.0V) VOUT - 0.008 _______mV VOUT + 0.008 40µV

PARD (Ripple and Noise)

23 RMS 0 _______mV 0.003 450µV
23 Peak-to-Peak 0 _______mV 0.030 900µV
25 Transient Recovery 0 _______mV 0.075 9mV
(90% to 100% Full Load)

Constant Current Tests

26 Current Programming
and Readback

Low Current (0.500A) 0.4896 ________A 0.5104 221µA

Front Panel Display IOUT - 0.012 ________A IOUT + 0.012 221µA
HP-IB Readback IOUT - 0.012 ________A IOUT + 0.012 221µA
High Current (10.00A) 9.9815 ________A 10.0185 4.1mA
Front Panel Display IOUT - 0.031 ________A IOUT + 0.031 4.1mA
HP-IB Readback IOUT - 0.031 ________A IOUT + 0.031 4.1mA
27 Load Effect (3.30A) IOUT - 0.0053 ________mA IOUT + 0.0053 2µA

27 Source Effect (10.0A) IOUT - 0.003 ________mA IOUT + 0.003 4µA

27 PARD (Ripple and Noise) 0 ________mA 0.005 750µA

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 E
Manual Backdating
This section describes changes that must be made to the manual so that it applies to instruments with serial numbers lower
than those listed on the title page. Look in the following table for the serial number of your insrument, and make only those
changes listed for your instrument. Note that for some changes you may be instructed to update the instrument if certain
components are being replaced during repair.
_____________________________________
CHANGE 1 (continued)
| Prefix | Serial Number | Make Changes |
Delete: R2,12 4.64K 1%, p/n 0698-3155, qty 2.
| 6033A |
R79,80 0 ohm, p/n 8159-0005, qty 2.
| 3004A | 05092-05096 | 1-10 |
U117 IC-9914 talker/listener, p/n 1821-1740.
| 3024A | 05272-06111 | 1-10 |
Change: A8, HP-IB board to p/n 5060-3551.
| 3124A | 06112-06591 | 1-10 |
C14 to 0.047uF, p/n 0160-5422.
| 3211A | 06592-06691 | 1-10 |
C23 to 39uF, p/n 0180-0393.
| 3223A | 06692-07051 | 1-9 |
C61 to p/n 0160-4281.
| 3251A | 07052-07091 | 1-8 |
U6 to p/n 5080-2160.
| 3303A | 07092-07171 | 1-7 |
U36 to p/n 5080-2158.
| 3313A | 07172-07251 | 1-6 |
| 3329A | 07252-07691 | 1-5 | CHANGE 2:
| 3430A | 07692-07831 | 1-4 | Under A4 Power Mesh board, change Q3,4 to transistor
| 3442A | 07832-07951 | 1-3 | PFET, p/n 1855-0547.
| 3506A | 07952-08561 | 1, 2 |
CHANGE 3:
| 3649A | 08562-08881 | 1 |
Under A8 HP-IB Board, change U33 to p/n 1820-0430.
| US3649 | 0101-0230 | 1 |
| | | | CHANGE 4:
| 6038A | Under A8 HP-IB Board, change U14 to p/n 1820-6721.
| 2933A | 08856-08860 | 1-10 |
CHANGE 5:
| 3025A | 09316-11135 | 1-10 |
Under A8 HP-IB Board:
| 3122A | 10396-06591 | 1-10 |
Add: U15, p/n 1LH4-0001.
| 3212A | 11136-11255 | 1-10 |
Delete: U115, SN75ALS61610, p/n 1820-6045.
| 3221A | 11256-11655 | 1-9 |
U116, SN75ALS6160, p/n 1820-6170.
| 3250A | 11656-11695 | 1-8 |
C142 100pF, p/n 0160-4801.
| 3304A | 11696-11815 | 1-7 |
C143-144 .047uF, p/n 0160-5422.
| 3309A | 11816-12075 | 1-6 |
Change: A8, HP-IB board to p/n 5060-3305.
| 3329A | 12076-12545 | 1-5 |
| 3431A | 12546-12655 | 1-4 | CHANGE 6:
| 3440A | 12656-12855 | 1-3 | Under A1 Main Board Assembly, Change CR1,3 to p/n
| 3511A | 12856-13825 | 1, 2 | 1901-1087. Change CR2,4 to p/n 0901-0759.
| 3651A | 13826-14195 | 1 |
CHANGE 7:
| US3831 | 0101-0400 | 1 |
Under A3 Front Panel, change G1 to p/n 06033-60007.
CHANGE 1: Under Chassis Mechanical, change Knob to p/n 0370-
Under A8 HP-IB Board. 1303.
Add: R100 p/n 0698-4037. CHANGE 8:
U17 p/n 1820-2549 Under A1 Main Board Assembly, change C13, 14 to
Delete: C67-70 0.01uF 10%, p/n 0160-4832, qty 4. 0.022uF, p/n 0160-5933.
C71,73 2200pF 10%, p/n 0160-4830, qty 2.
CHANGE 9:
L1 choke, p/n 9170-1680.
Under A8 HP-IB Board, change U8 to p/n 1818-4111.
L2-4 core-shield bead, p/n 9170-1454, qty 3.
Q1 transistor 2N4917, p/n 1853-0089. CHANGE 10:
R1 47.5K 1%, p/n 0757-0457. Under A8 HP-IB Board, delete D22.

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