Tektronix. COMMITTED TO EXCELLENCE WARNING THE FOLLOWING SERVICING INSTRUCTIONS ARE FOR USE BY QUALIFIED PERSONNEL ONLY. TO AVOID PERSONAL INJURY, DO NOT PERFORM ANY SERVICING UNLESS YOU ARE QUALIFIED TO DO SO. PLEASE CHECK FOR CHANGE INFORMATION AT THE REAR OF THIS MANUAL. 2215 OSCILLOSCOPE SERVICE INSTRUCTION MANUAL Tektronix, inc. P.O. Box 500 Beaverton, Oregon 97077 070-3826.00 First Printing JUL 1981 Product Group 48 Revised AUG 1982 Serial NumberCopyright © 1981 Tektronix, Inc. All rights reserved, Contents of this publication may not be reproduced in any form without the written permission of Tektronix, Inc. Products of Tektronix, Inc. and its subsidiaries are covered by U.S. and foreign patents andlor pending patents. TEKTRONIX, TEK, SCOPE-MOBILE, and are registered trademarks of Tektronix, Inc, TELEQUIPMENT is a registered trademark of Tektronix U.K. Limited Printed in U.S.A. Specification and price change privileges are reserved. INSTRUMENT SERIAL NUMBERS Each instrument has a serial number on a panel insert, tag, or stamped on the chassis. The first number or letter designates the country of manufacture. The last five digits of the serial number are assigned sequentially and are Unique to each instrument, Those manufactured in the United States have six unique digits. The country of manufacture is identified as follows: 8000000 Tektronix, Inc., Beaverton, Oregon, USA 100000 Tektronix Guernsey, Ltd.. Channel Istands 200000 Tektronix United Kingdom, Ltd., London 300000 Sony/Tektronix, Japan 700000 Tektronix Holland, NV, Heerenveen, ‘The Netherlands2218 Service TABLE OF CONTENTS LIST OF ILLUSTRATIONS LIST OF TABLES. OPERATORS SAFETY SUMMARY. SERVICING SAFETY SUMMARY. . SECTION 1 SPECIFICATION INTRODUCTION . ACCESSORIES, PERFORMANCE CONDITIONS SECTION 2 OPERATING INSTRUCTIONS PREPARATION FOR USE SAFETY LINE VOLTAGE POWER CORD LINE FUSE CONTROLS, CONNECTORS, AND INDICATORS. . . POWER, DISPLAY, AND PROBE ADJUST. . VERTICAL HORIZONTAL, TRIGGER REAR PANEL OPERATING CONSIDERATIONS. GRATICULE GROUNDING SIGNAL CONNECTIONS. INPUT COUPLING CAPACITOR PRECHARGING. . INSTRUMENT COOLING OSCILLOSCOPE DISPLAYS. INTRODUCTION BASELINE TRACE. SIGNAL DISPLAY MAGNIFIED-SWEEP DISPLAY. DELAYED-SWEEP DISPLAY DELAYED-SWEEP MEASUREMENTS. X.Y DISPLAY e Page Ml uM MM 24 24 24 24 24 23 23 23 225 26 28 29 29 229 29 29 240 210 2.10 210 210 2ay 21 an 212 SECTION3 THEORY OF OPERATION INTRODUCTION GENERAL DESCRIPTION DETAILED CIRCUIT DESCRIPTION VERTICAL ATTENUATORS Input Coupling High-Z Attenuator. . Buffer Amplitier andl Low-2 Attenuator: Volts/Div Var Circuit ond X10 Amplifier VERTICAL PREAMPS, : Channel 1 Vertical Preamplifier Channel 2 Vertical Preamplifier Internal Trigger Pickotf Amplifier CHANNEL SWITCH AND VERTICAL OUTPUT Diode Gates Delay Line Driver Delay Line Vertical Output Amplifier AJB Sweep Separation Circuit ‘Channel Switching Logic Gireuit, Internal Trigger Switching Logic TRIGGER. Internal Tigger Amplifier. Trigger Source-Switching Circuit, ‘A External Triggor Amplifier ‘Auto Trigger Circuit “Trigger Level Comparator Inverting Amplifier and TV Trigger Circuit Schmitt Trigger Circuit. Auto Bateline Circuit A SWEEP GENERATOR AND Loaic Miller Sweep Generator ‘Sweep Logic. Page 34 32 34 34 34 35 35 . 36 36 36 37 37 37 . 37 39 39 39 39 39 340 343, 343 343 313 343 a4 aia 315 315 316 346 3172218 Service TABLE OF CONTENTS (cont) SECTION 3 THEORY OF OPERATION (cont) ALTERNATE B SWEEP. Run After Delay 8 Delay Time Position Comparator B Sweep Logic Alternate Display Switching Logie B Z-Axis Logie AUTO INTENSITY AND Z AXIS AMPLIFIER, Auto Intensity Z-Axis Amplifier HORIZONTAL. . Sweep Switching. Horizontal Preamplifier XY Amplifier. . - Horizontal Output Amplifier POWER SUPPLY Power Input Preregulator Inverter CRT Supply ‘Auto Focus Circuit Low-Voltage Supplies DC Restorer SECTION 4 PERFORMANCE CHECK PROCEDURE INTRODUCTION. PURPOSE ‘TEST EQUIPMENT REQUIRED LIMITS AND TOLERANCES PREPARATION INDEX TO PERFORMANCE CHECK STEPS, VERTICAL HORIZONTAL, TRIGGERING EXTERNAL Z-AXIS AND PROBE ADJUST. 348, 349, 219 349) 320 320 321 321 322 3.23 324 324 = 3:24 3.24 325 3.25 3.25 3.26 327 327 327 327 at at at 41 41 43 44 46 49 SECTIONS SECTION 6 ADJUSTMENT PROCEDURE INTRODUCTION PURPOSE . : TEST EQUIPMENT REQUIRED LIMITS AND TOLERANCES. PARTIAL PROCEDURES ADJUSTMENT INTERACTION PREPARATION FOR ADJUSTMENT. : INDEX TO ADJUSTMENT PROCEDURE. POWER SUPPLY AND CRT DISPLAY VERTICAL HORIZONTAL, TRIGGERING EXTERNAL Z-AXIS AND PROBE ADJUST. MAINTENANCE STATIC-SENSITIVE COMPONENTS PREVENTIVE MAINTENANCE INTRODUCTION GENERAL CARE INSPECTION AND CLEANING LUBRICATION SEMICONDUCTOR CHECKS PERIODIC READJUSTMENT TROUBLESHOOTING. INTRODUCTION : TROUBLESHOOTING AIDS ‘TROUBLESHOOTING EQUIPMENT TROUBLESHOOTING TECHNIQUES CORRECTIVE MAINTENANCE INTRODUCTION MAINTENANCE PRECAUTIONS OBTAINING REPLACEMENT PARTS MAINTENANCE AIDS INTERCONNECTIONS Page SI 51 Ba 51 Ba 51 83 83 54 . 87 513 518 521 61 62 62 62 62 64 64 65 65 65 66 66 610 10 610 610 610 6102215 Service TABLE OF CONTENTS (cont) SECTION 6 MAINTENANCE (cont) TRANSISTORS AND INTEGRATED CIRCUITS SOLDERING TECHNIQUES, REMOVAL AND REPLACEMENT INSTRUCTIONS. Cabinet Cathode-Ray Tube. High-Voltage Shield Alt Sweap Circuit Board Attenuator/Sweep Circuit Board Front-Panel Circuit Board Main Circuit Board Current Limit Circuit Board REPACKAGING FOR SHIPMENT. Page 61 6-12 613 613 613 14 o14 615 16 617 618 19 SECTION? OPTIONS SECTION 8 REPLACEABLE ELECTRICAL PARTS SECTION 9 DIAGRAMS SECTION 10 REPLACEABLE MECHANICAL PARTS ACCESSORIES. INTERNATIONAL SALES & SERVICE OFFICE! U.S. SALES & SERVICE OFFICES CHANGE INFORMATION2218 Service Figure 24 22 23 24 25 26 27 28 aH 32 33 34 35 37 38 44 et ot 92 93 24 35 96 97 98 99 210 on LIST OF ILLUSTRATIONS ‘Tho 2215 Oscilloscope Power-input-voltage configurations. Line fuse and power cord : Power, display, and probe adjust controls, connector, and indicator - Vertical contrals and connectors Horizontal controls “rigger controls, connector, and indicator Rear-panel connector Graticule measurement markings Basic block diagram of the 2216 Oscilloscope... . ae Detailed block diagram of the Channel 1 attenuator and attenuator switching tables Diode gate biasing for a Channel 1 display . . CHOP VERTICAL MODE waveforms... {A Swoep timing diagram Simplified diagram of the Z-Axis Switching Loge circuit Detailed block diagram of the Horizontal Amplifier. . ‘Simplified diagram of the DC Restorer circuit. Test setup for external trigger and jitter checks. - Multipin connector orientation . . . Color codes for resistors and capacitors Semiconductor lead configurations. Locating components on schematic diagrams and circuit board illustrations. 2216 block disgram. ‘A12—Attenuator/Sweep board Circuit view of A12—Attenuator/Sweep board, Circuit view of A10—Main board, A10—Main board, A11-Front Panel board, ‘A19—Current Limit board, A13--Alt Sweep board. 235 Pace . 22 22 28 24 25 26 28 28 33 38 230 + 316 321 323 327 410 eTTable 4 12 13 44 43 4a 45 46 5a 52 53 84 55 56 87 58 61 62 63 64 LIST OF TABLES Electrical Char Environmental Characteristics, Physical Characteristics. Test Equipment Required. Deflection Accuracy Limits. Settings for Bandwidth Checks. . ‘and B Timing Accuracy Settings for Timing Accuracy Checks : ‘Switch Combinations for A Triggering Checks. Adjustmont Interactions Power Supply Limits and Ripple Deflection Accuracy Limits. Attenuator Compensation Adjustments ‘Sottings for Bandwidth Chocks, ‘Acand B Timing Accuracy Settings for Timing Accuracy Checks Switch Combinations for A Triggering Checks. Relative Susceptibility to Statie-Discharge Damage External Inspection Checklist Internat Inspection Checklist. Maintenance Aids 2215 Service Page 12 16 7 42 44 45 46 a7 49 52 55 58 510, 1 515 515 . B19 61 63 63 en2216 Service OPERATORS SAFETY SUMMARY The general safety information in this part of the summary is for both operating and servicing personnel. Specific warnings and cautions will be found throughout the manual where they apply and do not appear in this summary. Terms in This Manual CAUTION statements identify conditions or practices ‘that could result in damage to the equipment or other property, WARNING statements identify conditions or practices ‘that could result in personal injury or loss of lite. ‘Terms as Marked on Equipment CAUTION indicates 2 personal injury hazard not imme- diately accessible as one reads the markings, or ahazard to property, including the equipment itself. DANGER indicates a personal injury hazard immediately ‘accessible as one reads the marking, ‘Symbols in This Manual This symbol indicates where applicable cautionary or other information is to be found. For maximum input voltage see Table 1-1, ‘Symbols as Marked on Equipment 4 DANGER — High voltage. © Protective ground (earth) terminal ZA ATTENTION — Rotor to manual Power Source This product is intended to operate from a power source that does not apply more than 250 volts rms between the supply conductors or between either supply conductor and round. A protective ground connection by way of the grounding conductor in the power cord is essential for safe operation. Grounding the Product This product is grounded through the grounding eonductor of the power cord. To avoid electrical shock, plug the ower cord into a properly wired receptable before con: necting to the product input or output terminals, A protective ground connection by way of the grounding Conductor in the power cord is essential for safe operation, Danger Arising From Loss of Ground Upon loss of the protective-ground connection, all acces: sible conductive parts (Including knobs and controls that ‘may appaar to be insulating) can render an electric shock. Use the Proper Power Cord Use only the power cord and connector specified for your product. Use only a power cord that isin good condition, For detailed information on power cords and connectors see Figure 2-1. Use the Proper Fuse To avoid fire hazard, use only a fuse of the correct type, voltage rating and current rating a5 specified in the parts list for your produet, Do Not Operate in Explosive Atmospheres To avoid explosion, do not operate this product in an ‘explosive atmosphere unless it has been speci‘cally cor tified for such operation, Do Not Remove Covers or Panels To avoid personal injury, do not remove the product covers or panels. Do not operate the product without the covers and panels property installed.2215 Service SERVICING SAFETY SUMMARY FOR QUALIFIED SERVICE PERSONNEL ONLY Refer also to the preceding Operators Safety Summary. Do Not Service Alone Do not perform internal service or adjustment of this product unless another person capable of rendering first aid and resuscitation is present. Use Care When Servicing With Power On Dangerous voltages exist at several points in this product. To avoid personal injury, do not touch exposed connec: tions or components while power is on ® Disconnect power before removing protective panels, soldering, or replacing components. Power Source This product is intended to operate from a power source that does not apply more than 250 volts rms between the supply conductors or betwoen either supply conductor and ground. A protective ground connection by way of the grounding conductor in the power cord is essential for safe operation,2218 Service ‘The 2218 Oscilloscope. viii @‘Section 1-218 Service SPECIFICATION INTRODUCTION The TEKTRONIX 2215 Oscilloscope is @ rugged, light ‘weight, dual-channel, 60-MH? instrument that features a bright, sharply defined trace on an 80- by 100%mm cathode. ray tube (ert), Its vertical system provides calibrated deflection factors from 2 mV per division to 10 V per division, Trigger circuits enable stable triggering over the full bandwidth of the vertical system. The horizontal system provides calibrated sweep speeds from 0.8 per division to 50ns per division along with delaved-sweep features for accurate relative-time measurements, A X10 magnifier extends the maximum sweep speed to S ns per division, ACCESSORIES ‘The instrument is shipped with the following standard 1 Operators manual 1 Service manual 2 Probe packages 2 Probe grabber tips For part numbers and further information about both standard and optional accessories, refer to the “Accossories” page at the back of this manual. Your Tektronix represent ative, your local Tektronix Field Office, or the Tektronix product eatalog can also provide accessories information. PERFORMANCE CONDITIONS The following electrical characteristics (Table 1-1) are valid for the 2218 when it has been adjusted at an ambient temperature between +20°C and +30°C, has had a warmup period of at least 20 minutes, and is operating at an ambient temperature between OC and +50°C (unloss otherwise noted). Items listed in the “Performance Requirements” column are verifiable qualitative or quantitative limits, while items listed in the "Supplemental Information’ column are either explanatory notes, calibration setup descriptions, performance characteristics for which no absolute limits ‘are specified, or characteristics that are impractical to cheek. Environmental characteristics are given in Table 1-2 The 2215 meets the requirements of MIL-T-288008, Class § equipment, except where otherwise noted. Physical characteristics of the instrument are listed in Table 1-3,Specification-2218 Service Table 11 Electr | Characteristics Characteristics Performance Requirements ‘Supplemental information VERTICAL DEFLECTION SYSTEM Deflection Factor Range 2 mV per division to 10 V per division in 21.25 sequence, ‘Accuracy 420°C to ¥30°C 23%, Octo +80°C 242 1X gain adjusted with VOLTS/DIV switch set to 20 mV per division, 10X gain adjusted with VOLTS/DIV switch set to 2 mV per division, Range of VOLTS/DIV Variable Control Continuously variable between settings, Inereases deflection factor by at least 28101. ‘Stop Response Riso Time Measured with a vertically centered S.division reference signal from 2 60-92 source driving a 50-2. coaxial cable that is terminated in 50 9 at the input connector, with the VOLTS:DIV Variable control in its CAL detent. 5B ns or less, Rise time is caleulated from the formula: 0.36 Rise Time = Bay (in MHZ) Bandwidth O'co +40°C 20 mV to 10 V per Division De to at least 60 MHz 2 mV t0 10 mV per Division De to at least 50 MH +40°C 10 450°C. 2 mV to 10 V per Division De to at least 50 MH2.® Measured with a vertically centered 6-division reference signal from a 50-2 source driving a 60-02 coaxial cable that is terminated in 60 £2, both at the Input connector and at the P6120 probe input, with the VOLTS/DIV Variable control in its CAL detent, Chop Mode Repetition Rate 250 kH2 +30%, Performance Requirement not chacked in Service Manual 12Table 1-1 (cont) ‘Specification—2215 Service Characteristics Performance Requirements ‘Supplemental Information VERTICAL DEFLECTION SYSTEM (cont) Input Characteristics, Resistance 1M. #258 Capacitance 30 pF £3 pF* ‘Maximum Sate Input Voge ZA, ¢ Causes 400 V (de + peak ac) or 800 V p-p ac to 1 KHz oF less.® AC Coupled 4400 V (de + peak ac) or 800 V pip ac to 1 kHz or less. ‘Common-Mode Rejection Ratio (cmaR} Atleast 10 to 1 at 10 MH2, Checked at 20 mV’ per divsion for ‘common-mode signals of & divisions or less, with VOLTS/DIV Variable control adjusted for best CMRR at 50 kHz, ‘TRIGGER SYSTEM A Trigger Sensitivity AUTO and NORM. (0.4 division internal or 50 mV external 10 2 MHz, increasing to 1.5 divisions internal or 250 mV external at 60 MHz, AUTO Lowest Usable Frequency 202s TV FIELD 2.0 divisions of composite video or composite syne.* External tigger signal from a 50-92 source driving a 50-2 coaxial cable ‘that is terminated in 50 at the input connector. Will trigger on tv ine synecomponents in NORM only: > 0.4 division internat ‘or 50 mV pp external B Trigger Sensitivity Internal 0.4 division to 2 MHz, increasing to 2.0 divisions at 60 MHz, Exel pet Maximum Input Vrs ZA, 400 V (de + peak ac) or 800 V pp ac at 1 KHz or less? Input Resistance 1M 22%." Input Capacitance 30 pF +3 pF* AC Coupled 10 Hz or less at lower ~3 48 point.* Performance Requirement not checked in Service Manual 13Specitication—2215 Servi Table 1-1 (cont) Characteristics Performance Requirements Supplemental Information ‘TRIGGER SYSTEM (cont) LEVEL Control Range ‘A Trigger (NORM) INT EXT and DC (On seroen li | iaeciaa eee eel Atleast #2 V (4V ppl? EXT and DC+ 10 Atleast #20.V (40 V pp) B Trigger Internal (On soreen limits* VAR HOLDOFF Control Range Increases the A Sweep holdoff time by at least a factor of four.* HORIZONTAL DEFLECTION SYSTEM Sweep Rate Calibrated Range A Sweep 0.8 s per division to 0.05 ps per division ing 1.2.5 sequence. X10 Magnifier lextends maximum sweep speed to 5 ns per division, 8 Sweep '50 ms per division to 0.05 4s per division ina 1-2 sequence. X10 Magnifier ‘extends maximum sweep speed to 6 ns per division, Accuracy Unmagnified Magnified ‘Sweep accuracy applies over the center B divisions. Exclude the first 25 ns of 420°C to 430°C 23% 25% the sweep for both magnified and un- ‘magnified sweep speeds and exclude O° t0 +50°C sae 6% anything beyond the 100th magnified POSITION Control Range i | ‘Start of sweep to 100th division will position past the contor vertical graticule line with X10 Magnifier. division, Variable Control Range Continuously variable between calibrated settings. Extends both the A and B sweep speeds by at least a factor of 2.5. Delay Time B DELAY TIME POSITION Control Range Applies to sweep-speed settings of 0.5 us Per division and slower. Less than 0.6 division to more than 10 divisions, Delay time is functional but is not calibrated at sweep speed settings above 0.5 us per division. Performance Requirement not checked in Service Manual. 14 REV ocr tTable 1-1 (cont) ‘Specification—2215 Service Characteristics Performance Requirements ‘Supplemental Information HORIZONTAL DEFLECTION SYSTEM (cont) Delay Time (cont) sitter One part, oF loss, in 10,000 (0.01%) of | the maximum available delay time. Dial Accuracy 41.5% of full scale, X-¥ OPERATION (X1 MAGNIFICATION) Deflection Factors Range ‘Same as Vertical Detlection System, with both VOLTS/DIV Variable controls in CAL detent, Accuracy X-Axis v Measured with a de-coupled, 5-division reference signal 420°C to 430°C 15% 13% OFC to 450°C 26x? 24K? Bandwidth Measured with a S-division reference signal X-Axis Dc to at least 2 MHz Y-axis Same as Vertical Deflection System. Phase Difference Botwaen X- and Y-Axis Amplifiers 43° from de to 50 kHz? With de-coupled inputs. PROBE ADJUST Signal at PROBE ADJUST Jack Voltage 05 V #20%. Repetition Rate kHz +20%8 Z-AXIS INPUT Sensitivity 5 V causes noticeable modulation. Positive-going input signal dacreasos intensity. Usable Frequency Range De to 5 MHz" Maximum Safe Input Voltage 30 V (de + peak ac) or 30 V pep ac at kHz or less Input Impedance 10k 10% “Performance Requirement not checked in Service Manus 15‘Specification—2215 Service Table 1-1 (cont) Characteristies Performance Requirements ‘Supplemental Informetion POWER SOURCE Line Voltage Range 90 V to 250 v* Line Frequency Range 48 Hz to 62 Hz? Maximum Power Consumption sows Line Fuse 2A, 280 V, fast. | CATHODE-RAY TUBE Display Area 80 by 100 mm.* ‘Standard Phosphor Pate Nominal Accelerating Voltage 10,000 v#* “Performance Requirement not checked in Service Manu. Table 12 Environmental Character Characteristics Description NOTE The instrument meets all of the following MIL-T-288008 requite- ‘ments for Class 5 equipment. ‘Temperature Operating 0°C to 450°C (+32°F to H122°F}. Nonoperating 86°C to 475°C (-67°F to H167°FI Altitude Operating ‘To 4,500 m (15,000 ft). Maximum operating temperature decreased 1°C per 300 m (1,000 ft) above 1,500 m (5,000 ft). Nonoperating To 18,000 m (50,000 ft), Humidity (Qperating and Nonoperating) 5 cycles (120 hours} referenced to MIL-T-28800B, Class § instruments, Vibration (Operating) 16 minutes along each of 3 major axes at a total displacement of 0.015 inch pp (2.4 g at 85 Hz), with frequency varied from 10 Hz to 55 Hz to 10 Hz in ‘rminute sweeps, Hold for 10 minutes at §§ Hz, All major resonances must be above 55 Hz Shock (Operating and Nonoperating) 30 g,half-sine, 11-ms duration; 3 shocks per axis each direction, for a total of 18 shocks. 16Specification-2215 Service Table 13 Physical Characteristics Characteristics Deseition Weight With Front-Panel Cover, Accessories, and Pouch 76 ks (16.81. Without Front Panel Cover, Accessories, and Pouch 6.1 kg (13.516). Domenie Shipping 8.29 (18010) Height With Feet and Handle 137 mm (54h, wiatn With Hanae 361 me (142 in. Without Handle 328 mm (12.9 in. Depth With Front ane! Cover 445 mm (175 eh. Without Front-Panel Cover 4439 mm (17.3) With Handle Extended 511 mn (20.1 in. WwSection 22215 Service OPERATING INSTRUCTIONS PREPARATION FOR USE SAFETY Refer to the Safety Summaries at the front of this manual for power source, grounding, and other safety ‘considerations pertaining to the use of the 2215. Before connecting the instrument to a power source, carefully read the following information about line voltages, power cords, ‘and fuses; then verify that the proper power-input fuse is installed LINE VOLTAGE The instrument is capable of continuous operation using ae-power-input voltages that range from 90 V to 250 V nominal at frequencies from 48 Hz to 62 Hz, POWER CORD For the 120-V North American customer, the 2215 is delivered with a threswire power cord’ permanently attached. At the end of the cord is @ three-contact plug for ‘connection to the power source and to protective ground. ‘The plug's protective-ground contact connects (through the protective-ground conductor) to the accessible metal parts, Of the instrument. For electrcal-shock protection, insert this plug only into a power-source outlet that has a securely ‘grounded protective-ground contact. REV SEP 1961, For the non-North American customer (and for the 240-V North American user), the appropriate power cord is supplied by an option that is specified when the instrument is ordered. The optional power cords availabe are ilustrated in Figure 2-4 LINE FUSE ‘The instrument fuse holder is located on the rear panel (see Figure 2:2) and contains the line fuse. Verify that the proper fuse is installed by performing the following procedure: 1, Unplug the power cord from the power.input source (if applicable) 2. Press in and slightly rotate the fuse-holder cap coun- terclockwise to release it 3. Pull out the cap from the fuse holder, with the fuse attached to the inside of the cap. 4, Note fuse values and verify proper size (2 A, 250 V, fast-blow) 5. Reinstall the fuse and fuse-holder cap. 24Operating Instructions—2215 Service Pg Power Cond trate Line Cort ‘confgurstion category sna Pog Plog Fase U5, Domest us 2A 2ov cle tov Fac AGc/aAG Nene ntion A ov Fanon 5x20 mm ene 10188 520mm ux 20.250¥ an Ontion a2 aw Fat blow 5:20 mm twee 138 5220 mm 2A 250¥ Ootion a3 Fas blow 9920 mm Noa Non Ameries 2A.250v Onion A pao Fasctiow Accrang fone ton ASRS Figure 21. Powerinputvoltape configurations. une Fuse Power CORD 22 Figure 22 Line fuse and power cord.Operating Instructions—2216 Service CONTROLS, CONNECTORS, AND INDICATORS The following descriptions are intended to familiarize the operator with the location, operstion, and function of the instrument's controls, connectors, and indicators. POWER, DISPLAY, AND PROBE ADJUST Refer to Figure 2:3 for location of items 1 through 7. ©) Internal Gratieute— Eliminates paralax viewing error between the trace and graticule lines. Rise-time amplitude and measurement points are indicated at the left edge of the graticule @ POWER switeh—Tums instrument power on and oft CC ® AUTO FOCUS Control— Adjusts display for optimum. definition, Once set, the focus of the ert display will Figure 2:3. Power, display, and probe adjust control, connector, nd indision REV Nov 1981 bbe maintained as changes occur in the intensity level of the trace, @ PROBE ADJUST Connector Provides an approx imately 0.5.V, negative-going, square-wave voltage {at approximately 1 kHz) that permits the operator to Compensate voltage probes and to check operation of the osciloscope vertical system. It is not intended to verify the accuracy of the vertical gain or time-base calibration, © BEAN FIND Switeh—When held in, compresses the display to within the graticule area and provides @ visible viewing intensity to aid in locating offscreen displays, @® taace ROTATION convot-Serewhiver con used to align the ert trace with the horizontal graticule lines. @ Avro Wrensiry contot-Adiusts bighines of the ert display, This control has no effect when the BEAM FIND switch is pressed in. Once the control is set, intensity is automatically maintained at approximately the same level between SEC/DIV switch settings from 0.5 ms per division to 0.05 us per division. VERTICAL Rofer to Figure 24 for location of items 8 through 16. © SERIAL and Mod siotsThe SERIAL sot i ine printed with the instrument's serial number, The Mod slot contains the option number that has been Installed in the instrument. © e811 on x and cH 2 OR ¥ Conacon-Provie for application of extornal signals to the inputs of the vertical deflection system or for an X-Y display. In the X-¥ mode, the signal connected to the CH 1 OR X connector provides horizontal deflection, and the signal connected to the CH 2 OR Y con. ‘ctor provides vertical deflection, GND Connector-Provides direct connection to instrument chassis ground. 23Operating Instructions—2218 Sorvice Figure 2-4. Vertical controls and connectors Input Coupling (AC-GND-DC) Switches—Used 10 select the method of coupling input signals to the vertical deflection system, ‘AC~Input signal is capacitively coupled to the vertical amplifier. The de component of the input signal is blocked, Low-frequency limit (-3 dB point) is approximately 10 Hz. GND—The input of the vertical amplifier is grounded to provide a zero (ground) reference. voltage display (does not ground the input signal). ‘This switch position allows precharging the input ‘coupling capacitor. DC-All frequency components of the input signal are coupled to the vertical deflection system. @ 111 voursioiv and cH2 VOLTS/DIV Suiteher- Used to select the vertical deflection factor in a 1-25 sequence, To obtain a calibrated deflection factor, the VOLTS/DIV variable control must be in detent. 1X PROBE-Indicates the deflection factor selected when using either a 1X probe or a coaxial cable, 10X PROBE-Indicates the deflection factor salected when using a 10X probe. @ vorrsyowv variable Conots— ven rotates cou terclockwise out of their detent positions, these con- ‘trols provide continuously variable, uncalibrated deflection factors between the calibrated settings of the VOLTS/DIV switches. Extends maximum uncalibrated deflection factor to 25 volts per division with IX probe (a range of at least 2.5:1), INVERT Switch—Inverts the Channel 2 display when button is pressed in, Push button must be pressed in a s8cond time to release it and regain a noniaverted display. VERTICAL MODE Switches—Two three-position switches are used to select the mode of operation for ‘the vertical amplifier system. CH 1-Selects only the Channel 1 input signal for display. BOTH-Selects both Channel 1 and Channel 2 input signals for display. The BOTH position must bbe selected for either ADD, ALT, or CHOP operation. CH 2-Selects only the Channel 2 input signal for display. ADD—Displays the algebraic sum of the Channel 1 and Channel 2 input signals. ALT~Alternately displays Channel 1 and Channel 2 input signals, The alternation occurs during retrace at the end of each swoop. Thit mode is useful for viewing both input signals at sweep speeds from 0.05 ys per division to 0.2 ms per division, CHOP-The display switches between the Chan- nel-1 and Channel 2 input signals during the sweep. The switching rate is approximately 250 kHz, This mode is useful for viewing both Channel 1 and Channel 2 input signals at sweep speeds from 0.5 ms per division to 0.5 s per division. ee display on the ert. When the SEC/DIV switch is set to XY, the Channel 2 POSITION control moves the display vertically (Y-axis), and the Horizontal POSITION contra! moves the display horizontally (axis). REV SEP 1981HORIZONTAL Refer to Figure 2.5 for location of items 17 through 23, @ b DELAY TIME POSITION contrl-salet tne trount of daly tine between the Hart ofthe A Sireep ad the tat of the 8 Sweep Delay time Yarabis om 0.5 times 10 times the A SECTOIV voc etm @ A mae sec/o1v switns-Used ost te sp tones for he A and B Sup geerators in 0 125 treuere, For caltated veep somes, dw A and B SECIDIV Varale control must be he calirated detent (fully clockwise). @ vane 8 secrow v. Operating Instructions—2215 Service ‘A SEC/DIV—The A Sweep speed is shown between the two black lines on the clear plastic skirt. This switch also selects the delay time for delayed-swoep operation (used in conjunction with the 8 DELAY TIME POSITION control). B SEC/DIV—The B Sweep spoed is set by pulling out the DLY'O SWEEP knob and rotating it clockwise to a setting shown by the white line ed on the knob. The B Sweep circuit is used only for delayed-sweep operation le Control—Provides con: ‘tinuously variable, uncalibrated A Sweep speeds to at least 2.5 times the calibrated setting, It extends the slowest sweep speed to at least 1.25 s per division, a 390.08) Figure 25. Horizontal controls,Operating Instructions—2216 Service ) X10 Magnifier Switch—To incroase displayed sweep speed by 2 factor of 10, pull out the A and B SEC/ DIV Variable knob. The fastest sweep speed can be extended to 5 ns per division, Push in the A and B SEC/DIV Variable control knob to regain the X1 sweep speed, HORIZONTAL MODE Suwitch—This three-position switch determines the mode of operation for the horizontal deflection system. A-Horizontal deflection is provided by the ‘A Sweep generator at a sweep speed determined by the A SEC/DIV switch setting, B-Horizontal deflection is provided by the B Sweep generator at a sweep speed determined by the setting of the 8 SEC/DIV switch. The start of the B Sweep is delayed from the start of the ‘A Swaep by a time determined by the settings oF oth the A SEC/DIV switch and the 8 DELAY TIME POSITION control ALT-Alternates the horizontal displays between the A Sweep (with an intensified zone) and the B Delayed Sweep. The A Sweep speed is deter mined by the setting of the A SECIDIV switch, ‘The length of the intensified zone on the A Sweep {the B Sweep speed) is determined by the setting of the 8 SEC/DIV switch, POSITION Control—Positions the display hori zontally for the A Sweep and the B Sweep. In the X-¥ mode, horizontally positions the X-axis. @ Ave suv se convl-Vorisly. postions the 26 B Sweep trace with respect to the A Sweep trace when ALT HORIZONTAL MODE is selected. TRIGGER Rofer to Figure 26 for locations of items 24 through 33. EXT INPUT Connector—Provides a means of intro: ducing external signals into the A Trigger generator. @® next covrcins switen-Determines the method used to couple external signals to the A Trigger AC-Signals above 60 Hz ate capscitively coupled to the input of the A Trigger circuit. Any de com- Ponents are blocked, and signals below 60 Hz are attenuated. DC-All components of the signal are coupled to ‘the A Trigger circuitry. This position is useful for displaying low-frequency or low-repetition-rate signal, Figure 26. Trigger controls, connector, and indeator.DC+10—External trigger signals are attenuated by 2 factor of 10. @ A SOURCE switchDetemines the source of the ‘rigger signal that is coupled to the input of the A Trigger circuit, INT—Permits triggering on signals that are applied to the CH 1 OR X and CH 2 OR Y input con- rectors, The source of the internal signal is selected by the A & B INT switch LINE-Provides a triggering signal from 2 sample of the ac-power-source waveform. This trigger soureo is useful when channel-input signals are time rolated (multiple or submultiple) to the frequency on the power-source-input voltage. EXT-Permits triggering on signals applied to the EXT INPUT connector. @ 4.8 Int switen-sees the source ofthe tig ‘ering signal when the A SOURCE switch is set to INT. CH 1—The signal applied to the CH 1 OR X input Connector is the source of the trigger signal VERT MODE-The internal trigger source is determined by the signals selected for display by the VERTICAL MODE switches. CH 2-The signal applied to the CH 2 OR Y input connector is the source of the trigger signal. @ artiocen Lever cont-suot the amplitude point on the trigger signal at which the sweop is triggered, REV SEP 1981 Operating Instructions—2215 Se TRIG'D Indicator—The lightemitting dode (LED) illuminates to indicate that the A Sweep is triggered, ‘SLOPE Switches—Used to select the slope of the ‘signal that triggers the sweep (also refer to TV Signal Displays at the end of Section 2) S-Sweep is triggered on the positive-going Portion of the trigger signal. \-Sweep is triggered on the negative-going portion of the trigger signal. @ A raiser Move switeh-cetermins the wise mode for the A Sweep. AUTO-Permits triggering on waveforms having repetition rates of at least 20 Hz, Sweep free-runs in the absence of an adquate trigger signal or when the repetition rate is below 20 Hz. The range of the A TRIGGER LEVEL control is automaticaly set to the peak-to-peak range of the trigger level NORM-Swoop is initisted when an adequate trigger signal is applied. In the absenc> of a trigger signal, no baseline trace will be prosert. Triggering ‘on television lines is accomplished in this mode. TV FIELD—Permits triggering on teevision field signals (refer to TV Signal Displays at the end of Section 2). @ e raiccen ever contl-scects he amplitude point on the trigger signal at which the sweep is triggered, When fully clockwise (CW-RUN AFTER DLY}, the B Sweep circuit runs immediately following the delay time selected by the A SEC/OIV ‘switch and the B DELAY TIME POSITION contro VAR HOLDOFF Control-Provides continuous con: trol of holdoft time between sweeps. Increases the holdoff time by at least a factor of four. This ‘control improves the ability to trigger on aperiodic signals (such as complex digital waveforms)Operating Instructions—2215 Service REAR PANEL Rofer to Figure 2.7 for location of item 34, @exx z axis connoetor-Provides 2 means of con heating externa signal 10 the Zaxi amplifier to Intensity modulate the ert display. Applied signals do not affect display waveshape. Signals with fast rise times and fall times provide the mest abrupt intensity change, and 2 5-V pp signal will produce noticeable modulation, The Z-axis signals must be time-related to the display to obtain a stable present ation on the ert Figure 27, Reaepanel connector. 28Operating Instructions2215 Service OPERATING CONSIDERATIONS ‘The following basic operating information and tech: niques should be considered before attempting any measurements. GRATICULE The graticule is internally marked on the faceplate of the ert to enable accurate measurements without parallax error (see Figure 2-8). It is marked with eight vertical and ten horizontal_major divisions, Each major division is divided into five subdivisions. The vertical deflection factors and horizontal timing are calibrated to the graticule so that accurate messurements can be made directly from the crt, Also, percentage markers for the measurement of ise and fall times are located on the left side of the graticule GROUNDING ‘The most reliable signal measurements are made when the 2215 and the unit under test are connected by 2 com: mon reference (ground lead), in addition to the signal lead for probe. The probe's ground lead provides the best ‘grounding mothod for signal interconnection and ensures ‘the maximum amount of signal-lead shielding in the probe cable, A separate ground lead can also be connected from the unit under test to the oscilloscope GND connector located on the front panel 1ST OR LEFT center THOR RIGHT VERTICAL VERTICAL VERTICAL Gaaricure Graricuce GRATICULE tine Line’ tine’ RISE AND center FALL TIME HORIZONTAL, MEASUREMENT ‘SnaTicuLe PERCENTAGE Line SIGNAL CONNECTIONS Generally, probes offer the most convenient means of connecting an input signal to the instrument. They are shielded to prevent pickup of electromagnetic interference, and the supplied 10X probe offers a high input impedance ‘that minimizes circuit loading, This allows the circuit under tost to operate with @ minimum of change from its normal condition as measurements are being made, Coaxial cables may also be used to connect signals to the input connectors, but they may have considerable effect on the accuracy of a displayed waveform, To maintain the original frequency characteristics of an applied signal, only high-quality, low-loss coaxial cables should be used, Coaxial cables should be terminated at both ends in their characteristic impedance. If this is not possible, use suitable impedance-matching devices. INPUT COUPLING CAPACITOR PRECHARGING When the input coupling switch is set to GND, the input signal is connected to ground through the input coupling capacitor in series with a TMQ resistor to form a pre charging network, This network allows the input coupling ‘capacitor to charge to the average de-voltage level of the signal applied to the probe, Thus, any large voltage transients that may accidentally be generated will not be applied to the amplifier input when the input coupling switch is moved from GND to AC. The precharging net: ‘work also provides 8 measure of protection to the external circuitry by reducing the current levels that can be drawn, from the external circuitry during capacitor charging, ‘The following procedure should be used whenever the probe tip is connected to a signal source having a different dc level than that previously applied, especially if the de- level difference is more than 10 times the VOLTS/DIV switch setting 1. Set the AC-GND-DC switch t0 GND before con: necting the probe tip to a signal source, 2, Insert the probe tip into the oscilloscope GND 29Operating Instructions—2215 Service 3, Wait several seconds for the input coupling capacitor ‘0 discharge. 4, Connect the probe tip to the signal source. 5 Wait several seconds for the input coupling capacitor to charge 6. Set the AC-GND-DC switch to AC. The display will remain on the screen, and the ac component of the signal ‘can be measured in the normal manner. INSTRUMENT COOLING To maintain adequate instrument cooling, the ventila- tion holes on both sides and rear panel of the equipment cabinet must remain free of abstructions OSCILLOSCOPE DISPLAYS INTRODUCTION ‘The procedure in this section will allow you to set up ‘and operate your instrument to obtain the most commonly used oscilloscope displays. Before starting this procedure, verify that the POWER switch is OFF (push button out), ‘then plug the power cord into an approved ac-power-source outlet, BASELINE TRACE First obtain a baseline trace. 1, Proset the instrument front-panel controls as follows: Display AUTO INTENSITY Fully counterclockwise minimum) AUTO Focus Midrange Vertical (Both Channels) AC-GND-DC ac VOLTS/DIV 50m (1X) VOLTS/DIV Variable CAL detent fully clockwise) VERTICAL MODE cHT INVERT Off (button out) POSITION Midrange Horizontal ‘Aand B SEC/DIV ‘and B SEC/DIV Variable Locked together at 0.5 ms CAL detent (fully clockwise) HORIZONTAL MODE =A X10 Magnifier Off (variable knob in} POSITION Midrange B DELAY TIME POSITION Fully counterclockwise ‘AB SWP SEP Midrange 2-10 A Trigger VAR HOLDOFF NORM {fully counter: clockwise) SLOPE J (lever up) LEVEL Midrange MODE AUTO AEXT COUPLING AC ‘SOURCE INT ARBINT VERT MODE SF (lover up) Fully clockwise 2, Press in the POWER switch button (ON) and allow the instrument to warm up for 20 minutes. 3. Adjust the AUTO INTENSITY control for desired display brightness, 4, Adjust the Vertical and Horizontal ‘controls 10 center the trace on the screen, POSITION SIGNAL DISPLAY 1, Obtain a baseline trace, 2. Apply a signal to either vertical-channel input con: nector and set the VERTICAL MODE switch to display the channel used, To display two time-related input signals use both vertical-channel input connectors and select BOTH VERTICAL MODE; then select either ALT or CHOP, depending on the frequency of input signals.3. Adjust the AUTO INTENSITY control for desired display brightness. If the display is not visible with the AUTO INTENSITY control at midrange, press the BEAM FIND push button and hold it in while adjusting the appropriate VOLTS/DIV switch(es) to reduce the vertical display size. Center the compressed display within the ] Tyee, | purge, aize[y [eee Je) recive ‘ee ras, oss 5 | Oise, 0130 nis 8.015 Yay 1.045 8.0%, 8.0%5 x10 GaN oe ATTENUATOR Lowe ArTewaTor naa we vars] a1 [ose VOU | a1 [ras] os va] oo [xe zat ape Tav F sev) x sav = a Sav x tomv | x anv | x ea x zw | x zn |X zen x soa) x Sov x son | x ‘oa nv) x aa wv z ‘ x 2a av x ae av | 200 av| x 509 mv x 50@ni x 00 wi] x zy x av | x sy x x sv | x v x z ev] x 20-21 Figure 32. Detailed block diagram ofthe Channel 1 attenuator and attenuator switching tables. High-Z Attenuator ‘Tho first section of attenuator switch S105A directs the input signal to one of three paths: directly through R103 (no attenuation); through @ 10X attenuator co sisting of C105, C107, R105, R106, R107, and R108; fr through a 10OX attenuator consisting of C111, C112, R110, R111, R112, R114, and R116, Medium-trequency ‘normalization of the input capacitance is accomplished by C104 in the 10X attenuator and by C110 in the 100% attenuator. Switch SIO5B connects the appropriate attenuator output to the input of the Buffer Amplifier Buffer Amplifier and Low-Z Attenuator ‘The Buffer Amplifier presents a high-impedance, low: ‘capacitance load to the input signal and delivers an accurate replica of that signal to @ low-impedance buffer output circuit, The Low-Z output circuit is composed of @ 250-0. voltage-divider network (R139F through R133) and the Volts/Div Var circuit (R141, C141, and R143}. Switch S1058 selects the appropriate output from the voltage divider. The Buffer Amplifier contains two paths: a slow path consisting of R116, R117, U120, and R119 in parallel with C119; and a fast path ‘through C121. The signals ‘through both paths are applied to the gate of Q122. In the slow-path portion, the input signal i divided by ten by the combination of R117 and R116 and is then applied to U120 pin 3. The Butfer Amplifier output signal is also divided by ten by the combination of R139B, 1290, R19BD, and RIGON. Sufficient de-gste bias for input FET Q122 is generated by the slow-path circuit to produce a null (zero difference) between pins 2 and 3 of U120. The closed-loop gain of the slow path is matched to the fest-path gain. If the average output voltage from the 35Theory of Operation—2215 Service fost path changes, transconductance amplifier U120 adjusts the de gate bias on Q122 to keep U120 pin 2 and U120, pin 3 nulled, This action keeps the slow-path and the fastpath gains matched. Resistor R119 isolates the output impedance of U120 from the input of FET 122. This iso- lation, in combination with the high input impedance of U120, prevents high-frequency loading of the input signal. Capacitor C119 compensates for the output capacitance of U120, Step Balance potentiometer R138 (at pin 1 of R139} is ‘adjusted to compensate for input offsets reaching U120 pins 2 and 3 when switching between VOLTS/DIV switch positions. In the fast path, the input signal is ac-coupled to input FET 0122 through C121. The input FET is arranged in @ source-follower configuration used to drive complementary emitter followers Q133 and Q134. The combination of Q125, R126, R131, R132, VA130, and R130 sets a constant current through R125 in the source lead of Q122. ‘The voltage drop across R126 biases 133 and Q134 for ‘about a 10mA idle eurrent. A bootstrap circuit composed of Q139, VR122, and R122 connects the Q122 drain to the Q122 source. This circuit forces the bias voltage across 0122 to remain con- stant, which in conjunction with the constant bias current supplied by R128, keeps 0122 operating at a constant power level to prevent distortion due to changing signal currents Complementary emitter followers Q133 and 0134 supply drive current to the +1, 22.5, and +5 voltage dividers ‘and provide impedance matching between input FET Q122 ‘and the divider network. The bias levels of 133 and Q134 are stabilized by emitter resistors R138A and R139E respectively. Average voltage changes occurring in the out- put of Q133 and 0134 are sensed through R139B and R139D which are connected to the point of lowest impedance (the emitters of Q133 and Q134). Resistor R139C provides a path that completes the feodback loop to the slow-path portion of the Buffer Amplifier. Volts/Div Var Circuit and X1/X10 Amplifier ‘The appropriate voltage divider signal output (1, £25, ‘or £5) iz selected by VOLTS/DIV switch $1058 and routed to the Volts/Div Var circuit composed of C141, R141, and R143, Changes that occur in the Buffer Amplifier ‘output impedance due to setting R141 or switching the vider output are sonsed via R139M. These changes modify the slow-path feedback signal to cause U120 to again match ‘the gain of both paths. 36 From the Volts/Div Var circuit, the signal is epplied to the input of the X1/X10 Switchable-gain Amplifier U145, ‘Amplifier U145 produces a differential output signal from the single-ended input signal. The gain of the amplifier Is controlled by the setting of VOLTS/DIV switch S105. ‘Amplifier gain is changed by switching between two pais of transistor amplifiers contained in U145. Gain of the X10 amplifier pair is adjusted by R145 to cbtain the ‘correct deflection factor for the 2m, 6m, and 10m VOLTS/ DIV switch positions. Resistors R148, R147, and R148 act to balance any de offsets between the X1 and X10 amplifiers. Trace shift occurring when the VOLTS/DIV Variable control is rotated is minimized by resistor R142 which stabilizes the input bias current to U145. VERTICAL PREAMPS ‘The Channel 1 and Channel 2 Preamp circuitry, shown in Diagram 2, includes the vertical preamplifiers, the internal trigger pickoff amplifiers, and a common-base ‘output stage for each channel. Vertical positioning of the channel display is Incorporated in the common-base amplifier stage, Channel 1 Vertical Preamplifier ‘The Channel 1 Vertical Preamplifier produces differ ‘ential output signals to drive the Vertiesl Outpu: Amplifior and internal trigger signals to drive the Trigger circuitry, Differential signal currant from the Attonuator circuitry is applied to common-base transistors Q187 and Q167 through cable-terminating resistors AIST and R161 respectively. The collector currents of Q187 and 0167 will flow through R188 and R168 to produce level-shifted signals which drive U1700 and U170E. Balance potenti ometer R154 is adjusted to balance the de level of the ‘Channel 1 output with the Channel 2 output by setting the bias levels of Q157 and Q167. Channel 1 frequency response is matched to Channel 2 response by adjusting c167. Transistors U170D and UT7OE form a common-emitter amplifier. The gain of U170D and U170E is sot by R180, (connected between the emitters), and the high-trequency response is compensated by C180. The emitters are also ‘connected to the bases of U170C and U170B respectively 10 provide an internal trigger signal pickoff point. Vertical signal output current flows from the collectors of UT70D and UITOE to the emitters of common-base amplifiers 0177 and 187. A shunt resistor gain network (R178 and R186) sets the gain of the common-base stage. Channel 1 POSITION control R190 supplies a variable offset current to the emitters of Q177 and Q187 which allows the teaceto be vertically positioned on the ert, The common-base ‘amplifier stage converts the differential signal input current to a differential signal output voltage that is applied to the Diode Gate circuitry (Diagram 3) Channel 2 Vertical Preamplifier ‘The Channel 2 Vertical Preamplifier functions the same as the Channel 1 Vertical Preamplifier previously described, with the exception of an additional pair of transistors that performs the inverting function. In the Normal mode Of operation, 0257 and 0267 are biased on and Q258 and (0268 biased off by INVERT switch $284 grounding one end of R263. In the Invert mode (INVERT switch pressed in), crosswired transistors 0258 and 0268 are biased on ‘and 0257 and 0267 biased off by grounding the junction of R256 and R266. Invert Bal potentiometer R264 is ‘adjusted to correct for de offsets botween the two ‘switching transistor pairs. When R264 is correctly adjusted, 2 baseline trace will maintain the same vertical position as ‘the amplifier is switched between Invert and Normal. Internal Trigger Pickoff Amplifier The Internal Trigger Pickoff Amplifier supplies trigger signals to the Internal Trigger Amplifier in the Trigger circuitry (Diagram 4). Internal trigger signals are provided by the vertical preamplifiers and are applied to the bases of U1708 and U170C (for Channel 1) and U270B and U27OC (for Channel 2). These transistor pairs aro biased on, either individually or together, from the Internal Triggor Switching Logic circuit (Diagram 3). When Channel 1 is the selected internal trigger source, Q173 and UI70A {CH 1) will be biased on and O273, (CH 2) biased off. Current flowing through R173, R183, and R197 will bias on UI97A to keep UI97E cut off, Emitter current is supplied to U170A by U197D. In turn, UITOA then supplies emitter current to U170B and U170C 10 enable the Channel 1 internal trigger signals to pass to the Internal Trigger Amplifier. When Channel 2 s selected as the internal trigger source, 0273 and U270A will be biased on and Q173 biased off, ‘Transistor U197A will remain on, and current supplied by 1970 will supply emitter current to U27OA. Then U270A, in turn supplies the emitter current to U270B and U270C. and enables the Channel 2 internal trigger signals to pass to the Internal Trigger Amplifier. ‘The actual signal source selected when the A TRIGGER A&B INT switch is set to VERT MODE depends on the setting of the VERTICAL MODE switches, If either CH 1 or CH 2 VERTICAL MODE js selected, the preceding discussion on Channel 1 or Channel 2 ‘internal trigger signals applies, When the VERTICAL MODE switch is set Theory of Operation2215 Service to BOTH, the VERTICAL MODE ADD-ALT-CHOP switch setting dotermines the switching action for selecting the internal tigger source. Selecting ADD VERTICAL MODE causes both internal triggerselect signals (CH 1 Trig and GH 2 Tri) to be LO, and both 173 and 0273 are biasod off. Transistor U197A, then becomes biased off causing UI97E to saturate. With U197E saturated, emitter current is supplied to both Channel 1 and ‘Channel 2 Trigger Pickoff Amplifiers (U170C and U1708 for Channel 1 and U270B and U270C. for Channel 2) via R196-CR196 and R296-CR296 respec: tively. When both pickoff amplifiers are enabled, the resulting trigger signal i the sum of the Channel 1 and Channel 2 internal trigger signals. The sum of the current supplied by U197E to both pickoff amplifiers is the same magnitude as the current from U197D when either CH 1 or CH 2 is selected individually, Therefore, the de output ‘to the Internal Trigger Amplifier will be the same for CH 1, (CH 2, and ADD VERTICAL MODE trigger signals, When ALT VERTICAL MODE is selected with the previously established settings (VERTICAL MODE to BOTH, A & B INT to VERT MODE, and A SOURCE to INT), ‘the internal triggerselect signals alternate between chanhols, On one sweep the Channel 1 internal trigger will be selected as previously described. On the alternate swaep, Channel 2 internal trigger will be selected, again as pre viously described. Under the same switch-setting conditions, selecting CHOP VERTICAL MODE produces the same trigger selection conditions as described for ADD VERTICAL, MODE. The sum of the Channel 1 and Channel 2 internal ‘rigger signals will be passed to the Internal Trioger Amplifier, See the “Internal Trigger Switching Logie” discussion for a description of how the internal trigger selection signals are generated, CHANNEL SWITCH AND VERTICAL OUTPUT The Channel Switch circuitry, shown on Diagram 3, solects the input signal or combination of input signals 10 be connected to the Vertical Output Amplifier. By setting ‘the logic input into the Channel Switching Logie circuit, VERTICAL MODE switches $318 and $317 select the input signal combinations to be displayed, The internal triggerselect signals are also generated in the Channel Switch circuitry. Diode Gates The Diode Gates, consisting of eight diodes, act as switches that are controlled by the Channel Switching 37Logic circuitry. The Q- and Qoutputs of U317A (pins 5 and 6 respectively) control forward biasing of the diodes to turn the gates on and off. CHANNEL 1 DISPLAY ONLY. To display only the Channel 1 signal, the CH 1 Enable signal (U317A pin 5) ig HI and tho CH 2 Enable signal (U317A pin 6) is LO. With CH 1 Enable Hi, gate diodes CR187 and CR177 are reverse biased (602 Figure 3:3). Series gate diodes CR18B and CRI78 are forward biased, and the Channel 1 vertical signal is allowed to pass to the Delay Line Driver. ALO CH 2 Enable signal applied to the Channel 2 gate diodes forward biases CR287 and CR277, and the Chan- nel 2 vertical-signal current is shunted away from serios diodes CR28B and CR278. The Channel 2 series diodes are roverse biased, and the Channel 2 signal current is proventod rom reaching the Delay Line Driver. CHANNEL 2 DISPLAY ONLY. When CH 2 VERTICAL MODE iis selected, the CH 1 Enable signal govs LO and the CH 2 Enable signal goes HI. The Channel 1 signal is blocked, and the Channel 2 signal reaches the Delay Line Driver ADD DISPLAY. Both Diode Gates are biased on to pass the Channel 1 and Channel 2 vertical signals, The channel signal currents are summed at the input to the Delay Line Driver, The Add Enable signal supplies the extra current required to keep both Diode Gates forward biased and to maintain the proper dc level at the base of the Delay Line Driver input transistors (331 and 0341), ALTERNATE AND CHOPPED DISPLAY. The Diode Gatos are switched on and off by the Channel Enable signals from the Channel Switching Logie circuit. When ALT VERTICAL MODE iis selected, the Diode Gates are switched at the end of each ‘trace, For CHOP VERTICAL MODE, the gates are switched at a rate of about 250 kHe. XY DISPLAY. Setting the A SEC/DIV switch to the X.Y position activates the X-Y display feature, The cu 2+ vertital sic cree . wz ZZREZZ VERTICAL sic ZLB PEPE E PA f ies WY cnie7 Og * ourewne, 1 From t Chane l cri? VERTICAL stCNAL sutenavc i ¥ 8 oetay Line Coere cee? ORLVER oe ewme | cR277 out 7 vestital sxc BE en cRi78 ot 2- rere ~~ ‘oro0e x rs ene 5220-25 Figure 33. Diode gate bi 38 ing for 8 Channel 1 display.Channel 1 Diode Gate is held off, and the Channel 2 Diode Gate is biased on, The Channel 2 signal is passed to the Delay Line Driver and ultimately to the ert to provide the Y-Axis display deflection. The X-Axis deflection signal is supplied to the XY Amplifier (Diagram 7) from the Channel 1 signal vis the Internal Trigger Amplifier (Diagram 4). Delay Line Driver ‘The Delay Line Driver converts the signal current from ‘the Diode Gates into a signal voltage for application to the Dalay Line, The Delay Line Driver is configured as a differential shunt feedback amplifier and is composed of (0331, 0335, 341, and Q345, Input currents to common- ‘emitter transistors’ Q331 and 341 are converted to voltages at tho bases of Q335 and 0345 respectively. Emitter-follower output transistors 0335 and 0345 then drive the Delay Line through reverse terminations R335: C335 and R245-C345. Amplifier compensation is provided by R340 and C340, and shunt feedback is supplied by 336 and R345, Delay Line Delay Line DL950 provides about 100 ns of delay in the vertical signal. When using internal triggering (CH 1 CH 2, or VERT MODE), the dolay time allows the Swoop Generator sufficient time to produce a sweep before the vertical signal reaches the ert deflection plates, This foature permits viewing the leading edge of the internal signal that originates the trigger pulse. Vertical Output Amplifier ‘The Vertical Output Amplifier, also shown on Diagram 3, provides final amplification of the input signals for appli cation to the deflection plates of the ert. Signals from the Delay Lino are applied to a differential amplifier input stage composed of 0360 and Q360. The Delay Line is ‘terminated in the proper impedance by resistors R&3B and R348, Resistor R355 sets the gain of Q350 and 0360, ‘Thermal compensation of the stage gain Is provided by thermistor RT356, connected in series with R356 across R355, The RC networks connected across R355 provide both low- and high-frequency compensation of the stage, ‘The differential output is applied to output transistor palts 0376-0377 and 0386-0387, These transistors form a common-emitter shuntfeedback amplifier stage, with R976, R377, R386, and R387 serving as feedback elements. Capacitors €377 and C387, connected across R377 and RQB7 respectively, provide’ increasing negative feedback as the signal frequency rises to limit the amplifier band: ‘width at the upper frequency limit. Output voltage from the amplifier is divided between the two transistors of each half, The signal voltage applied to the ert vertical deflection ‘Theory of Operation—2215 Service plates is the sum of voltage drops across the pairs (0376 0377 and 0386-0387). The deflection voltage is pro portional to the signal current driving the bases of 0376 ‘and 0386, BEAM FIND switch $390 (Diagram 6) normally supplies 86 V diractly to R390 to set the staye bias. When the BEAM FIND button is pressed in and hold, the direct voltage is removed and the —8.6-V bias is provided via series resistor R391. The output voltage swing is thereby reduced to hold the vertical trace deflection to within the agraticule area A/B Sweep Separation Circuit The circuit composed of 370, 0380, 0392, and ‘associated components provides a means of vertically positioning the B trace with respect to the A trace during ALT HORIZONTAL MODE displays, The Sep signal, provided by the Alternate Display Switching circuitry {Diagram 10), supplies the biasing voltage for 0392. During the B trace display portion of the Alternate Horizontal display, Sep is LO and 0392 is biased off, This action allows A/B SWP SEP potentiometer R395 to affect the bias on one side of a differential amplifier composed of 0380 and 0370. The differential amplifier supplies a de offset current to the Vertical Output signal that changes ‘the position of the B trace on the ert face. During the A trace portion of the Alternate Horizontal display, Sep is HI and 0392 is biased on, The base voltage. ‘on O360 then equals the baso voltage on 0370. With equal base voltages, the differential amplifier supplies equal current to both sides af the Vertical Output signal and no. offset to the A trace occurs. Channel Switching Lo The Channel Switching Logic circuitry composed of USIOA and UST7A selects either Channel 1 or Channel 2 and. various display modes for ert display via front-panel switches and the X-Y position of the A SEC/DIV switch. When the instrument is not in the X-Y Mode, signal Tine XY is grounded through contacts on the A SEC/DIV switch (Diagram 8). This action establishes LO logic levels fon pins C, 8, and G of front-panel switch $317 (CH 1- BOTH-CH 2) and on pins C and 8 of S305 (A & B INT). Switch $317 selects the vertical channel signal that drives the Delay Line Driver via the Channel Diode Gatos. With $317 set to CH 1, a LO is applied to the Set input (pin 4) of U3I7A. Flipsflop U317A will then be set, and ‘the Q output (nin 8) will be HI. Pin 5 of U317A is the CH 1 Enable signal line, and when itis HI, the Channel 1 vertical 39‘Theory of Operation-2216 Service signal is gated to the Delay Line Driver, Whon $317 is set to CH 2, the Reset input of U317A (pin 1} will be held LO through ‘CR706, The CH 2 Enable signal (U317A, pin 8) is. ‘hen sot HI and the Channel 2 vertical signal is gated to the Delay Line Driver. Setting $317 to the BOTH position removes the LO from both the Set and Reset inputs of UST7A. This action allows the channel selected for display to be determined either by the logic level applied to the D input (pin 2) and the clock applied to pin 3 oF by the logie level applied to the Set and Reset inputs from the ADD-ALT:CHOP switch The ADD-ALT-CHOP switch ($315) is enabled by the LO placed on pins A, C, and F when the CH 1-BOTH.CH 2 switch is set to BOTH. When in ADD, S315 holds both the Set and Reset input of U317A_LO through CR708 and CA701 respectively. The Q and O outputs of US17A will then be HI, and both Channel 1 and Channel 2 vertical signals are gated to the Delay Line Driver. The signal current is summed at the input to the Delay Line Driver, and the resulting oscilloscope Add vertical display is the algebraic sum of the two vertical signals, The Add Enable circuit, composed of 0316, U197C, and U315A, is activated when both Diode Gates are turned fon for an Add vertical display. With the Q and © outputs of U317A HI, the output of U315A will be LO and tran- sistor 0316 is biased on. The collector of 316 rises toward 45 V and U197C is biased on, Transistor U197C supplies the additional current required to keep both Diode Gates forward biased and to supply the proper de level to the Delay Line Driver input. Bypass capacitor C316 prevents switching transients from being introduced into the Delay Line Driver by the Add Enable circuit. When $316 is set to ALT, a HI is placed on both the Set and Reset inputs of U317A. Flip-flop U317A will transfer the logic level on the D input (pin 2) to the Q output (pin 5) on each clock-pulse rising edge. Pin 1 of NAND-gate US10A is held HI by the Chop Oscillator output, and pin 2 follows the AR Syne signal produced by the Holdoft circuitry in the A Sweep Generator (Diagram 5). The ‘output of UB10A (pin 3) is therefore an inverted Ait Syne pulse. The signal on the D input of U317A (pin 2) follows the logic evel set by the Q-output pin. As each clock pulse ‘occurs, the states of the Q and @ outputs reverse (togsl), enabling Channel 1 and Channel 2 Diode Gates alternately with each aween, CHOP OSCILLATOR. Setting $316 to CHOP enables the Chop Oscillator and the Chop Blanking circuit. Pins C and D of $315 are connected to place @ LO logic level on 3.10 the Set input (pin 10) of U317B. The Q output of U317B is set HI and the Chop Oscillator is allowed to run. A HI level is present on U3T0D pin 13 due to C308 being charged to the HI level on U310D pin 11. When pin 12.07 UBIOD also goes HI, the output of U310D goes LO, Capacitor C308 now must discharge to the new de level. ‘As soon as the charge of C308 reaches the LO threshold level of U310D, the output at pin 11 switches HI again and ‘€208 charges toward the HI logic level (see Figure 3-4). When the HI switching threshold level is reached, the output of U3O1D changes states to LO again. This cycle continues et about 600 kHz to produce both the Chop Clock and the Chop Blank signals, ‘The Chop signal is gated through NAND-gate U310C and applied to U310A pin 1. The Ait Sync pulse on US1OA pin 2 is HI (except during holdoff time) so the output of U310A pin 3 is the inverted Chop Oscillator signal on pin 1. This signal is applied to the Clock Input (pin 3) of USI7A to drive the Channel Switching circuitry, Since flip flop U317A clocks with rising edges only, the frequency of, ‘the chopped channel switching is about 250 KH2, ‘The signal autput from U310C pin 8 is also fed to the Chop Blanking circuit. Capacitor C311 and resistors R310 and R311 form a differentiating circuit that producos positive and negative short duration pulses when the Chop Oscillator signal changes levels The de level at U310B pins 4 and § is set slightly above the HI switching threshold logic by a voltage divider con: sisting of R310 and R311, Positive pulses from C311 con- tinue to hold U3T0B above the threshold level, so the ‘output remains LO. Negative pulses from C311 drop below the threshold level of U310B, and the output of U310B switches HI for 2 duration of about 0.4 us (see Figure 3.4) to produce the positive Chop Blanking pulse, The Chop, Blanking pulse is fed to the Z-Axis Amplifier and is used to prevent display of the transistions when switching between vertical channels. Internal Trigger Switching Logic Internal triggor-selection signals to the Trigger Pickott Amplifier (Diagram 2) are produced in a logic circuit com posed of U305B, U305C, U05D, U315B, and U315C. The A & B INT Trigger Source switch (S308), in con- junction with CH 1-BOTH-CH 2 switch ($317), determines ‘the internal trigger source selected. When either the CH 1 ‘or CH2 Internal Trigger signal is selected by $305, the selected channel will be the internal trigger source. When VERT MODE is solected as the internal trigger signal, the position of S317 determines the channel(s) selected as the internat trigger source.‘Theory of Operation-2215 Service — “6 cHor osciLLaton Ne FROM INTERNAL X-AKIS sic, | 3735 Gora TRIGGER AMPL ‘ FROM BEAM FIND Z-RKIS AHPL ‘028-22 Figure 3.7. Detaled block diagram of the Horizontal Amp e 3.23‘Theory of Operation=2215 Service Sweep Switching ‘Tha Sweep Switching circuit is composed of two tran: sistors, 0634 and Q684, acting as switches under control of, the Alternate Sweep Switching Logic circuit. Either the A Disp or the B Disp signal is applied to the base of the associated transistor (A Disp to Q684 and B Disp to 0634), and the sweep signals are applied to the collectors of the ‘switching transistors. The A Disp and B Disp signals are complementary (when one is HI the other is LO) so only fone sweep signal at a time will be applied to the Horizontal Preamplifier A SWEEP DISPLAY. To pass the A Swoop to the Horizontal Preamplifier, the A Disp signal is HI. Trensistor switch Q684 is biased on, and the B Sweep signal is shunted ‘to ground through the transistor. Since Q634 is biased off, the A Sweep signal is allowed to pass to the preamplifier summing junction at the base of Q730, Sweep signal ‘current is summed with the horizontal positioning current suppliad by Horizontal POSITION control R726. B SWEEP DISPLAY. The A Disp signal becomes LO and the B Disp signal applied to the base of 0634 becomes HI. Switching transistor 0634 is biased on, and the A Sweep ‘current is shunted to ground. The B Sweep current passes to the input summing junction to be added to the hori- zontal positioning current. The B Gain potentiometer (R682) is adjusted to provide the same gain for the B ‘Sweep signal as for the A Sweep signal. ALT HORIZONTAL DISPLAY. The A Disp and 8 Disp signals are switched at the alternate sweep rate by the Altwmate Sweep Switching Logic circuit. When both vertical channels are being viewed simultaneously, the intensified traces of both Channel 1 and Channel 2 are first displayed, then both alternate B traces are displayed. Horizontal Preamplifier ‘The sum of the sweep and positioning current is applied to the input of one side of a differential amplifier ‘composed of 0730 and Q731. For all conditions other than the XY Mode, XY Switch transistor Q720 is biased on to provide a ground reference at the other input of the dif ferential amplifier (at the base of 731). The output of the differential amplifier, taken from the collector of Q731, is amplified by 0736, A feedback network connected between the output of 0736 and the base of 0730 provides the circuitry required for the X10 magnification feature, In the unmagnified ‘mode, X10 Magnifier switch S734 is closed and the feed: back is provided by the paralleled combination of R732 ‘and C732. Resistor A732 sots the unmagnified amplifier gain and C732 provides the HF compensation. 3:24 When the X10 Magnifier push button is pressed in, $734 opens and additional components are added to the feedback network, With the feedback reduced, the amplifier gain is increased by a factor of 10. The X10 Gain Potentiometer (R733) is adjusted to produce the exact gain required. High-speed linearity compensation of the feed- bback network is provided by adjustable capacitor C734, XY Amplifier When the X-Y disolay mode is selected using the A SEC/ DIV switch, the XY signal line goes LO and XY Switch transistor Q720 is biased off, The XY signal is also applied to FET Q714 (used a a switch to prevent crosstalk) in the XY Amplifier to bias it on, With this action, the XY ‘Amplifier is enabled to pass X-Axis signals on to the Horizontal Preamplifier. Another function of the XY signal is to disable the A Swoop Generator to prevent the A and B Sweep signals from being applied to the Horizontal Preamplit ‘The X-Axis signal is derived from the Channel 1 internal trigger signal and applied to the base of Q703. Transistor 703 is one-half of a differential amplifier composed of 0703 and 0706. The base of 0706 is referenced to ground through R706. Transistor Q708 amplifies the output signal from the collector of Q706 and applies it to the drain of FET Q714, A feedback network composed of R709, R708, ‘and C708 is connected between the collector of Q708 and the base of 0703, The feedback network sets the overall ain of the XY Amplifier, with X-Gain potentiometer R708 adjustable to obtain the exact gain required. ‘The X-Axis signal passes through FET 714 and is ‘applied to the base of Q731 in the Horizontal Preamplifier. Horizontal positioning current on the base of 0730 is ‘added to the X-Axis signal by the action of the differential ‘amplifier. Then the sum of these two currents is amplified by 0736 and applied to the input of the Horizontal Output Amplifier Horizontal Output Amplifier The Horizontal Output Amplifier converts the single: fended output of the Preamplifier into the differential ‘output required to drive the ert horizontal deflection plates. The output stage consists of an input paraphase amplifier and an output complementary amplifier. Horizontal signal voltage from 0736 is applied to the base of Q763. The base of the other transistor (Q753) in the poraphase amplifier, is biased through a voltage divider ‘composed of R758, R757, and R756. Horizontal cantering betwen tho X1 and X10 Magnified sweeps is accomplished by adjusting Mag Registration potentiometer R758.Gain of the paraphase amplifier is determined by com: ponents connected between the emitter leads of 763 and 0753. The exact gain is adjusted by Horiz Gain potenti- ‘ometer R752. Transistor Q747 supplies the emitter current to both 0783 and Q753. The horizontal portion of the Beam Find circuitry affects the available current to Q747. Normally, 86 V is applied to the emitter of 747 from the BEAM FIND switch via CR745 and R746. When the BEAM FIND push button is pressed in, the direct -8.6 V is removed, In this condition, -86 V is supplied via R745 which reduces the current available, thereby reducing the output voltage swing capability of Q763 and Q753. Diodes CR772, CR782, CR783, and CR773 prevent the paraphase amplifier from overdriving the output amplifier stage when the X10 Magnification feature isin use, Final amplification of the horizontal deflection signal 's provided by the complementary-pair output stage. Both sides of the differential ourput amplifier are identical in function, s0 only one side is discussed in detail Transistors Q780 and Q785 form a cascode feedback amplifier. Gain of the stage is set by feedback resistor R785, and high-speed compensation is provided by C783 and adjustable capacitor C784, For de and low-frequency components of the horizontal deflection signal, Q789 acts as a current source for Q785. High-frequency components Of the signal are coupled through C789 to the emitter of (0789 t0 speed up the output response time. Emitter voltage for both Q780 and Q770 is supplied by 2 circuit composed of O765 and associated components. ‘Tho emitter voltage is maintained at a level that provides proper biasing for Q763 and Q763. Diodes CR770 and CR780 set up an emitter-bias difference between Q780 and 0770, causing the base voltage of both transistors to. be equal POWER SUPPLY ‘The Power Supply circuits provide all the low and high voltages required for operation of the instrument, The circuitry shown in Diagram 9 converts the acsource voltage to the required levels through the action of a switching power supply. It does not have a primary power transformer. Power Input The Power switch (S901) connects the line voltage to the instrument through line fuse F901 and transient sup: pressor VR9O1. Suppressor VR9O1 protects the instrument REV SEP 1981 ‘Theory of Operation=2215 Service from large voltage transients, High-frequency line noise is attenuated by C901. Preregulator ‘The Proregulator circuit converts the ac-power-source input voltage to a regulated de voltage. A tric is used as a switch to conduct current during a controlled period of the inputlinevoltage cycle so that energy to be used by ‘the Inverter circuit is stored in eapacitor C837. Current from one side of the ac-power-source input will go through L925 (a currentimiting impedance) and ‘riae 0925, Diodes CR931 and CRIS (on the Main board) and CR932 and CR9BA (on the Current Limit board) form a full.wave bridge rectifier circuit. The rectifier converts ‘the aciinput voltage into de pulses that charge C937. Surge arrestor VR938, connected in parallel with C937, conducts to protect the following circuitry should the Preregulator ‘output vottage become too high, The twostransistor circuit composed of 0933, 0938, {and associated components provides overcurrent protection in the event of triac misfiring or ac:power-source transients, Transistor Q938 isan insulated-gate FET used as a switeh in the charging path of C937. Transistor Q933 controls the FET bias to limit the current under abnormal firing conditions of 0925. In normal power-supply operation, the voltage developed across R937 is not sufficient to bias, (0933 into conduction. The gate-to-source voltage of 938, is set to 10 V by VR934 and FO3B, so the FET presents @ low resistance to the charging current to C937. If triac 0925 should misfire to cause excessive current, A933, bbecomes forward biased and 0938 is switched off to reduce the current. When Q938 switches off, the current that was, flowing through 0938 flows through R939. The voltage drop, developed across R939 causes current to flow through \VR933 and R933, which holds Q933 on for most of the remainder of the’ ac-power-source input cycle. Resistor R939 limits the rate of collapse of the field around L925 to prevent damage to Q938. Thermistor RT935 adjusts the bias of 2933 over varying ambient temperature. PREREGULATOR CONTROL. The acsource voltage is fullawave rectified by CR9O3 through CR9O6 and applied to a voltage divider composed of RO11, RO12, and R916, Output from this divider serves as a reference voltage for 2 ramp-and-pedestal comparator utilizing a programmable tunijunction transistor (PUT), 0921. Capacitor C912 filters tho Tine noise to prevent false triggering of the PUT. Voltage-dropping resistor R914 provides current for zener diodes VRO14 and VR915 to produce constant voltages during each half of the ae-power-source eye. When the instrument is first turned on, C917 is not charged. Capacitor C916 charges through CR917 to the 3.25‘Theory of Operation-2215 Service voltage of VR915 minus the diode drop of CROT7. When the anode voltage of 0921 is greater than the gate voltage, (0921 will fire and C915 will ischarge through the primary of 7925, This ovent will happen after the peak of the voltage waveform. Pulse transformer T925 is connected to the gate of 0925, and the discharge of C915 through the ‘7926 primary winding is coupled to the secondary to cause ‘triac 0925 to conduct. After firing, the tric will turn off again when the sinusoidal source voltage crosses through zero, As CO17 charges through RB17, OB18 current increases proportionally to charge C815 more rapidly. When C915 charges at 2 faster rate, the anode voltage of (0921 rises above the gate voltage earlier in the ac-source eyele and thereby causes 0925 to conduct for 2 longer period of time, The portion of the eyele preceding the zero. ‘crosting point over which the triac is conducting is called the conduction angle, The conduction angle will increase from nearly zero {at tum on) to an angle sufficient to supply the energy needed by the inverter. Feedback from the inverter through optical isolator U931 holds the correct conduction angle by shunting current from R917. This shunting action controls the voltage on C917, thereby ontolling the increase in base voltage on Q918. This action controls the charging rate of C915 and therefore the conduction angle of 0925, ‘The Preregulator circuit can handle a wide range of input voltages by changing the conduction angle of the trisc as, ‘the input voltage changes. As the input voltage increases, the conduction angle will decrease to maintain the Pre: regulator output voltage at a constant level. The voltage divider composed of R911, R912, and R91 produces fan output voltage proportional to the input line voltage ‘that is applied to the gate of Q921. Since VRO14 and VAQ15 hold bias levels on O91 constant regardless of put voltage, the point on the cycle at which Q921 fires ‘will vary with changes in the acsource voltage. This feed- forward, together with the feedback from the Inverter ‘through optical isolator U931, ensures a constant Pre- regulator output to the Inverter Inverter ‘The Inverter cirouit changes the de voltage from the Prerequlator to ac for use by the supplies that are con: nected to the secondaries of T3940. ‘The output of the Preregulator circuit is applied to the center tap of T940, Pawer-switching transistors 0940 and (0942 alternate conducting current through R941 from the primary cirauit common to the Preregulator output line, The transistor switching action is controlled by T942, 2 saturating base-drive transformer, When the instrument is first tured on, one of the switching transistors will start to conduct and the collector 3.26 voltage will drop toward the common voltage level, This will induce a positive voltage from the lead of T942 which is connected to the base of the conducting transistor to reinforce conduction, Eventually 7942 will saturate, and as the voltage across T842 {and T940) begins to reverse, the ‘conducting transistor cuts off because of the drop in bate drive, The other transistor will not start conduction until the voltage on the leads of T842 reverse enough 10 bias it fon, This process will continue, and the saturation time of T942 plus the transistor-switching time will determine the frequency of Inverter operation (typically 20 kHz). After ‘the initial Inverter startup, the switching transistors do not saturate; they remain in the active region during snitching, Diodes CR94O and CRB42 serve as a nogative-peak dotector to generate a voltage for controlling the outputs ‘of both the Preregulator and the error amplifier, Capacitor (C851 will charge to the peak amplitude of the collector voltage of 0940 and 0942. This voltage level is applied to the divider composed of R945, R946, and R47. The error amplifier, composed of Q948 and 0964, is a differontial amplifier that compares the reference voltage of VROSt with the voltage on the wiper of potentiometer ROM6. The current through 0954 will set the baso drive of 0956 and thereby control the voltage on C957. This veltage will bias 0940 and 0942 to a level that will maintain the peak- tespeak input voltage of T940. The amplitude of the voltage across the transformer primary winding and thus, that of the secondary voltages of T940, is sot by adjusting 8.6 V Adj potentiometer R946. At tun on, 0948 is biesed off and Q964 js tiased on. All the current of the error amplifier will therefore go through 954 to bias on Q966. Diode CR9BE allows the base of Q956 to go positive enough to initially turn on 0940 or 942. The eurrent through Q956 controls the base drive for 0940 and 0942. Base current provided by base drive transformer T942 will charge C957 negative with respect to the Inverter circuit floating ground (common) level. Voltage from CR940 and CR942 also provides a measurement of the minimum collector voltage of 0940 and 0942 with respect to the Inverter circuit floating ‘ground. This voltage is fed back to the Preregulater through optical isolator US31 to control the output vol:age from the Preregulator circuit. As the negative peak voltage at the collectors of the switching transistors is regulated by ‘the error amplifier with respect to the ouput of the Pre regulator, control of the de lovel from tho Prorogulator will control the minimum voltage with rospect to the floating ground, Potentiometer R952 (Head Room Voltage Adjust) is used t0 set this minimum vottage level to @ point that prevents saturation and excessive power dissipation of the Inverter switching transistors,CRT Supply High-voltage multiplier U89O utilizes the 2KV winding of T940 to generate 8 KV at one output to drive the ort anode. It also uses an internal halfavave rectifier diode to produce —2 KV tor the ert cathode, The ~2 KV supply is. filtered by a threo-stage low-pass filter composed of C990, R992, R980, C992, R994, C995, and RIVE. Neon lamp D870 protects against excessive voltage between the crt theater and ert cathade by conducting if the voltage exceeds approximately 75 V. Auto Focus Circuit Focus voltage is also developed from the ~2 kV supply via a voltage divider composed of R884, R882, AUTO FOCUS potentiometer R883, G81, R8B0, RE79, RB78, R872, Auto Focus Adjust potentiomter R875, and Q877. The focus voltage tracks the intensity level through the action of 0877. The Intens Level signal from the Auto Intensity circuit (Diagram 6) is applied to the emitter of 0877 through R877. When the Intens Level signal changes due to a changing display intensity, the current through the divider resistors changes proportionally. Auto Focus Adjust potentiometer R875 js adjusted to produce the best focus tracking Theory of Operation-2215 Service Low-Voltage Supplies The low-voltage supplies utilize the secondary windings of T940 and are all fullwave, center-tapped bridges. The +100 V supply uses CRIB1 and CR9B3 for rectification and uses C961 for filtering. Diodes CR965 and CR967 rectify ac from taps on the 100-V winding, ane OBS filters the output to produce +30 V de. The diode bridge con- sisting of CRQ71 through CRQ74 produces the +86 V and 886 V supplies, Filtering of the +86 V is accomplished by C971, C975, and L971; while filtering of the 86 V is done by C872, C976, and L972. Voltage regulator U9BS uses the rectified +86:V supply to produce the +5-V output, Diode CROBS protects the regulator by not allowing the output voltage to go more positive than the 48.6 V input voltage. DC Restorer ‘The DC Restorer circuit produces the ert control-grid bias and couples both de and low-frequency components of the Z-Axis Amplifier output to the ert control grid, Direct coupling of the Z-Axis Amplifier output to the ert control grid is not employed due to the high potential differences involved. Refer to Figure 3-8 during the following discussion. yt 0 rev +1ev Rees 2-axIS, ourPuT cre6s +100v GRID BIAS EBB Ree! “ANA VOLTAGE FROM ~ T948, PIN 15 “oll = Ress C864 CATHODE VOLTAGE ‘SUPPLY 2k) cees CONTROL GRID 1 CATHODE Figure 2.8, Simplified diagram of the DC Restorer citeut @ 3.27‘Theory of Operation-2215 Service “The ac drive to the DC Restorer circuit is obtained from pin 16 of T940, The drive voltage has a peak amplitude of about 150 V and a frequency of about 20 kHz. The sinu soidal drive voltage is coupled through C883 and RBBS into the DC Restorer circuit at the junction of CR860, CRE3, and R864. The cathode end of CR86O is held st about +85 V by the voltage applied from the wiper of Grid Bias potentiometer R860. When the positive peaks of the ac- drive voltage teach 2 level that forward biases CR86O, the voltage is clamped at that level The Z-Axis Amplifier outputsignal voltage is applied to the DC Restorer at the anode end of CR8E3. The Z-Axis signal voltage level varies between +10 V and +75 V, depending on the setting of the AUTO INTENSITY control ‘The accdrive voltage will hold CR863 reverse biased until the voltage falls below the Z-Axis Amplifier output voltage level. At that point, CR863 becomes forward biased and clamps the junction of CR860, CR863, and RA64 to the Z-Axis output level. Thus, the ac-drive voltage is clamped at ‘two levels on the positive swing of the eycle to produce an approximate squarewave signal with a positive do-offset level ‘The DC Restorer is referenced to the ~2-&V ert cathode voltage through R867 and CR867. Initially, both C865 and C864 will charge up to a level determined by the difference between the Z-Axis output voltage and the cathode voltage. Capacitor C865 charges from the crt cathode through R867, CR867, CRAGB, and REGS to the Z-Axis output. Capacitor C864 charges through R867, CR867, RAGA, and CR863 to the Z-Axis output. When the acdrive voltage starts its positive transition from the lower clamped level toward the higher clamped level, the charge on C864 increases due to the rising voltage 3.28 ‘The increase in charge acquired by C864 is proportional to the amplitude of the positive transistion. When the acrive Voltage stars its negative transition from the upper clamped level to the lower clamped level, the negative transition is coupled through C864 to reverse bias CREGT and to forward bias CR86B. The increased charge of CBG4 is then transferred to. C865 as C864 discharges toward the Z-Axis ‘output level. The amount of charge that is transferred is proportional to the setting of the AUTO INTENSITY ‘control, since that control sets the lower clams the accdrive voltage. ‘Tho added charge on CBGS also determines the control ‘rid bias voltage. If more charge is added to the charge already present on C865, the control grid becomes more negative, and less ert writing-beam current will flow, Conversoly, if less charge is added, the control-grid voltage level will be closer to the cathode-voltage level, end more cert weiting-beam current flows. During periods that C864 is charging, the ert control-grid voltage is held constant by the long time-constant discharge path of C865 through R868, Fastrise and fastfall transitions of the 2-Axis output signal ace coupled to the ert control grid throush C865, ‘The fast transitions start the ert writing beam current toward the new intensity level. The DC Restorer output level then follows the Z-Axis output-voltage level to set the new bias voltage for the ert control grid. Neon lamps S867 and DS868 protect the ert from excessive grid-to-cathode voltage if the potential on either the control grid or the cathode is lost for any reascn.Section 4—2215 Service PERFORMANCE CHECK PROCEDURE INTRODUCTION PURPOSE The “Performance Check Procedure” is used to verify the instrument's Performance Requirements 28 listed in the "Specification" (Section 1) and to determine the need for readjustment, These checks may also be used as an ‘acceptance test, as a preliminary troubleshooting ald, and ‘8 a check of the instrument after repair. Removing the instrument's cover is not necesary to preform this pro: cedure, All checks are made using the operator-accessible front- and rear-panel controls and connectors, To ensure instrument accuracy, its performance should bbe checked after every 2000 hours of operation or once ‘each year, if used infrequently. TEST EQUIPMENT REQUIRED The test equipment listed in Table 4-1 is @ complete list of the equipment required to accomplish both the Performance Check Procedure” in this section and the “Adjustment Procedure" in Section 5. Test equipment specifications described in Table 4-1 are the minimum. necessary to provide accurate results. Therefore, equipment Used must meet or exceed the listed specifications. Detailed ‘operating instructions for test equipment are not given in this procedure. If more operating information is required, refer to the appropriate test-equipment instruction manual. When equipment other than that recommended is used, Control settings of the test setup may need to be altered, I the exact item of equipment given as an example in ‘Table 4-1 is not available, first check the “Purpose’ column to verify use of this item. If itis used for a check that is of little or no importance to your measurement require: ‘ments, the item and corresponding steps may be deleted, If the check is important, use the “Minimum Specification” column carefully to determine if any other available test equipment might suffice, @ Special fixtures are used only where they simplify the test setup and procedure. These fixtures are available from Tektronix, Inc. and can be ordered by part number through ‘your local Tektronix Field Office or representative. LIMITS AND TOLERANCES ‘The tolerances given in this procedure are valid for an instrument that is operating in and has been previously calibrated in an ambient temperature between +20°C and 430°C. The instrument also must have had as least @ 20- minute warmup period. Refer to the “Specification” (Section 1) for tolerances applicable to an instrument Operating outside this temperature range, All tolerances specified are for the instrument only and do not include testequipment error, PREPARATION Test equipment items 1 through 9 in Table 4-1. are required to accomplish a complete Performance Check. At the beginning of each subsection, in both the “Performance Check Procedure” and the “Adjustment Procedure” sections, there is an equipment-required list showing only. the test equipment necessary for performing the steps in ‘that subsection, In this lst, the item number that follows each piece of equipment corresponds to the item number listed in Table 4-1 ‘This procedure is structured in subsections, which can bbe performed independentiy, to permit checking individual portions of the instrument. At the beginning of each subsection is 2 list of all the front;panel control settings Fequired to prepare the instrument for performing Step 1 in that subsection. Each succeeding step within a particular subsection should then be performed, both in the sequence presented and in its entirety, to ensure that control-setting changes willbe correet for ensuing steps, atPerformance Check Procedure—2215 Service Table 41 ‘Test Equipment Required tem No. and Minimum Examples of Suitable Description Specification Purpose “Test Equipment 1. Calibration Generator | Standard-amplitude signal | Vertical and horizontal TEKTRONIX PG 508 levels: 10 mV to 50 V. checks and adjustments. Calibration Genorator* Accuracy: *0.3%. High Amplitude signal levels: 1V 0 60V. Repetition rate: 1 kHz, Fastrise signal level: 1 V. Repetition rate: 1 MHz. Rise time: 1 ns oles. Flatness: 40.5%, 2. Loveled Sine Wave Frequency: 250 kHz to above | Vertical, horizontal, and TEKTRONIX SG 503 Generator 70 MHz. Output amplitude: | triggering checks and Leveled Sine Wave variable from 10 mV to 5 V_| adjustments Generator Pp. Outputimpedance: 502. | Display adjustment and Reference frequency: 60 kHz, | Z-axis check. ‘Amplitude accuracy: constant Within 35 of reference fre- ‘quency as output frequency changes. 3, Time-Mark Generator | Marker outputs: 10 ns to | Horizontal checks and ‘TEKTRONIX TG 501 Time- 0.5 s. Marker accuracy: adjustments Mark Generator? 40.1%. Trigger output: 1 ms | Display adjustment, 10.0.1 us, time-coincident with markers. 4, Cable (2 required) Impedance: 60.2. Length: | Signal interconnection. “Tektronix Part Number 42 in. Connectors: bne. 012-0087-01. 5. Termination Impedance: 502. Signal termination. Tektronix Part Number (2 required) Connectors: bno. 011-0049.01 6. Dual-input Coupler | Connectors: bne-female-to- | Vertical checks and Tektronix Part Number dual-bne male. adjustments, 067-0525-01. 7. 10X Attenuator Ratio: 10X, Impedance: 5022.| Vertical compensation and | Tektronix Part Number Connectors: ne. ‘triggering checks. 011-0059.02. 8, T-Connector Connectors: bne, ‘Signal interconnection, ‘Tektronix Part Number 103-0030.00. 98. Adapter Connectors: bne-male-to- | Signal interconnection. ‘Tektronix Part Number ‘miniature probe tip. 013.0084-02. 10. Variable Auto- Capable of supplying 1.5 A | Instrument input voltage Genoral Radio WEMT3VM. transformer at 18 V. adjustment, Variac Autotransformer. 42 REV SEP 1981Performance Check Procedure-2215 Service Table 4-1 (cont) Item No, and Minimum | Examples of Suitable Description ‘Specification Purpose Test Equipment 11, Digital Voltmeter Range: 0 to 140V. De voltage | Power supply checks and | TEKTRONIX DM 601A accuracy: #0.15%, 4 1/2-digit | adjustment. Digital Multimeter.® display, ‘Vertical adjustment, 12. Test Oscilloscope | Bandwidth: de to 10 MHz. | Power supply ripple check | a, TEKTRONIX 2213 with included 10X probe | Minimum deflection factor: | and general troubleshooting, | Oscilloscope. (Standard Accessory) and | 5 mV/av, Accuracy: 23% b, TEKTRONIX P6101 1X probe (1X probe Is Probo (1X), Part Number optional accessory). 010-6101.03, 13. DC Voltmeter Range: 0 to 2500 V,, ~ High-voltage power supply Triplett Model 630-NA. calibrated to 1% accuracy at | check, =2000 V, 14, Serewariver Length: in shat ‘Adjust variable resistors, Xenlite R-3923. Bit size: 3/32 in, 15, Low-Capacitance | Length: tin shaft. ‘Adjust variable capacitors. | J.F.D. Electronics Corp. Alignment Tool Bit size: 3/32 in. ‘Adjustment Too! Number 5264, Requires» TM 500-seres power-modile mainframe, INDEX TO Horizontal (cont) Page PERFORMANCE CHECK STEPS 4, Check Delay Time Dial Accuracy... 48 5. Check Delay Jitter 43 6. Check POSITION Control Range»... ses eee 88 Vertical ge 7 Chek Nan ete ae 1, Check Deflection Accuracy and Variable Range ... 4-4 Le cieteetectiaan - S ee. 2. Chock BandWidth ee eeveeveseeeeeee ss 45 Tyigge 3. Check Common-Mode Rejection Ratios... 45 1. Check Internal Triggering 2. Check External Triggering, Horizontal 1. Check Timing Accuracy... - 0. eevee ee AB External Z-Axis and Probe Adjust 2. Check Delay Time Postion Range 471, Check EXT Z-AXIS Operation... .- 212 43. Check SEC/DIV Variable Range... 12.1... 47 2, Check PROBE ADJUST Operation. . 412 EV SEP 1981, 43VERTICAL Equipment Required (see Table 4-1): Calibration Generator (Item 1) Levoled Sine-Wave Generator (Item 2) 502 BNC Cable (Item 4) INITIAL CONTROL SETTINGS POWER ON (button in) cRT AUTO INTENSITY ‘As dosirod ‘AUTO FOCUS Best focused display Vertical POSITION (both) Midrange VERTICAL MODE cHt CH 1 VOLTS/DIV 2mv cH 2 VOLTSIDIV tov VOLTS/DIV Variable (both) CAL detent INVERT Normal (button out) AC-GND.DC (both) oc Horizontal POSITION. Midrange HORIZONTAL MODE =A AND B SEC/DIV 05 ms A AND B SEC/DIV Variable CAL detent X10 Magnifier Off (knob in} Trigger VAR HOLDOFF NoRM ATRIGGER MODE AUTO ATRIGGER SLOPE t ATRIGGER LEVEL, Midrange A&BINT VERT MODE ASOURCE INT PROCEDURE STEPS 1. Check Deflection Accuracy and Variable Range @. Connect @ 10-mV standard-amplitude signal to the CH 1 OR X input connector using a 50-2 cable 44 50.0 BNC Termination (Item 5) Dual-Input Coupler (Item 6) b, CHECK Deflection accuracy is within the limits ‘iven in Table 4:2 for each CH 1 VOLTS/DIV switch sot ting and corresponding standard-amplitude signal. When at the 20-mV VOLTS/DIV switch setting, rotate the CH 1 VOLTS/DIV Variable control fully counterclockwise and CHECK that the display decreases to 2 divisions or less. Then return the VOLTS/DIV Variable control to ‘the CAL detent and continue with the 60-mV check, «. Set the VERTICAL MODE switch to CH 2 and move the cable from the CH 1 OR X input connector to the (CH 2.OR Y input connector Table 4.2 Deflection Accuracy Limits votts/oiv | standard | Vertical | 3% Accuracy Switch | Amplitude | Deflection | Limits Setting | Signal | (Divisions) | Divisions) 2mv tomv 4.85 10 5.18 smv | 20mv [ssa 104.12 1omv 50 mV 4.85 10 5.18 20mV ov 4.8510 5.15 50mv o2v 3.88 104,12 ov osv 4.85 105.15 02v Vv [4.85 to 5.15 o5V 2v 3.88 t0 4.12 1 sv | 4.85 10 5.15 2v tov 4.85 10 5.15, sv | av 3.88 10 4.12 tov s0v 4.35 10 5.15d. CHECK-Deflection accuracy is within the limits given in Table 4-2 for each CH 2 VOLTS/DIV switch set: ting and corresponding standard-amplitude signal. Perform ‘the checks from the bottom to the top of Table 4:2 to avoid unnecessary. switeh-position changes. When at the 20-mV VOLTSIDIV switch setting, rotate the CH 2 VOLTS/DIV Variable contro! fully counterclockwise and CHECK that the display decreases to 2 divisions or lass, Then return the VOLTS/OIV Variable control to the CAL detent and finish the check, , Disconnect the test setup, 2. Check Bandwidth a. Set: VOLTS/DIV (both 2mv SEC/OIV 20s b. Connect the leveled sinewave generator output via 2 50-2 cable and @ 50-( termination to the CH 1 OR X input connector. . Set the generator output amplitude for a S-division, SO-kH display 4d. Change the generator output frequency to the value shown in Table 4-3 for the corresponding VOLTS/DIV ‘switch setting Table 43 Settings for Bandwidth Cheeks voLts/oIv Generator Switeh Settings utput Frequency 2mV to 10 mV 50 MHz 20mV to 10V 60 MHz ©, CHECK~Display amplitude is 3.5 divisions or greater. {, Repeat parts © through ¢ for all indicated CH 1 VOLTSIDIV switch settings, up to the output-voltage upper limit of the sinewave generator being used. 8. Move the generator output signal from the CH 1 OR X input connector to the CH 2 OR Y input connector. Set the VERTICAL MODE switch to CH 2. Performance Check Procedure—2215 Service hh. Repeat parts ¢ through e for all indicated CH 2 VOLTS/DIV switch settings, up to the output-voltege Upper limit of the sine-wave generator being used 3. Check Common-Mode Rejection Ratio 2a, Set both VOLTS/DIV switches to 20 mV. b. Connect a 10.MHz, loveled sinewave signal via @ 50-9 cable, a 50-2 termination, and a dual-input coupler to the CH 1 OR X and the CH 2 OR Y input connectors. cc. Sot the generator output amplitude to produce a Gdivision display, 4. Vertically center the display using the Channel 2 POSITION control. Then set VERTICAL MODE to CH 1 and. vertically center the display using the Channel 1 POSITION control @. Set the VERTICAL MODE switches to BOTH and ADD; then push in the INVERT button. . CHECK-Display amplitude is 0.6 division oles. 4. If the check in part f meets the req) part n. If it does not, continue with part h, h, Set VERTICAL MODE to CH 1. i. Change the generator frequency to 60 kHz and adjust the output to obtain a 6-division display j. Set VERTICAL MODE to BOTH. k. Adjust the CH 2 VOLTS/DIV Variable contol for ‘minimum display amplitude (best CMR). |. Change the generator frequency to 10 MHz, m, CHECK—Display amplitude is 0.6 division or less, 1, Disconnect the test setup,Performance Check Procedure-2215 Service HORIZONTAL Equipment Required (see Table 4-1): Calibration Generator (Item 1) Leveled Sino.Wave Generator (Item 2) ‘Time-Mark Generator (Item 3) ‘Two 50-2. BNC Cables (Item 4) ‘Two 50-2 BNC Terminations (Item 5) INITIAL CONTROL SETTINGS POWER cRT AUTO INTENSITY ‘AUTO FOCUS Vertical Channel 1 POSITION VERTICAL MODE cH 1 VOLTS/DIV CH 1 VOLTS/DIV Variable INVERT Channel 1 AC-GND-DC Channel 2 AC-GND-OC Horizontal POSITION HORIZONTAL MODE ANAND B SEC/DIV ‘A AND B SEC/DIV Variable X10 Magnifier B DELAY TIME POSITION Trigger VAR HOLDOFF A TRIGGER MODE ‘SLOPE (both) LEVEL (both) AgBINT ‘SOURCE A EXT COUPLING 46 ON (button in) As desired Best focused display Midrange cHt sv CAL detent Normal {button out) De GND Midrange A 0.05 us CAL detent Off (knob in) Fully counterclockwise Noam NORM fe Midrange VERT MODE ExT oc=10 PROCEDURE STEPS 1. Check Timing Accuracy ‘a, Connect 60-ns time markers from the time-mark generator via 2 60-2 cable and a 50-0 termination to the (CH 1 OR X input connector. Connect the generator Trigger ‘output via a 60-2 cable and a 60-0 termination to the EXT INPUT connector. b, Use the Channel 1 POSITION control to center the trace vertically. Adjust the A TRIGGER LEVEL control for a stable, triggered display. ©. Use the Horizontal POSITION control to align the first time marker that is 50 ns beyond the start of the sweep with the 2nd vertical graticule line. NOTE When making timing measurements, use as a reierence the same point on each time marker. 8, CHECK—Timing accuracy is within the limits shown in Table 4-4 for the applicable position of the X10 Mag nifier. When making the check with the X10 Magnifier On, exclude any portion of the sweep past the 100th magnified division, Table 4-4 A and B Timing Accuracy X10 Magnifier | Accuracy at 10th Vertical Graticule Line 3% (0.24 division) (On (knob out) 5% (0.40 division), Set the HORIZONTAL MODE switch to 8 and adjust ‘the B TRIGGER LEVEL control for a stable display. 1. Align the first time marker that is 50 ns beyond the start of the sweep with the 2nd vertical graticule line, using the Horizontal POSITION control. 9. CHECK—Timing accuracy is within the limits shown in Table 4-4 for the applicable position of the X10 Mag: nifier. When making the check with the X10 Magnifier On, exclude any portion of the sweep past the 100th magnified division, hh, Sot the HORIZONTAL MODE switch to A. |. Repeat parts b through h for the A and & SEC/DIV and. time-mark generator setting combinations shown in Table 4-5 under the “Normal” column, Table 45 ‘Settings for Timing Accuracy Checks AANDB SEC/DIV ‘Switch Setting Normal | X10 Magnified 0.05 ys 50 ns 10ns Ot us Otus 10s O.2us O2us 20ne 0.5 ys 0.5us 50s tas Vas Ot us 2us 2us O.2us Sus Sas O5us 10 us 104s tus 204s 20 us 2us 50us 50 us Bus 0.1 ms 0.1 ms tous 0.2 ms 02ms 204s 05 ms 0.5 ms 50 us ims ims 0.1 ms 2ms 2ms 0.2 ms Sms 5ms 0.5 ms 10s 10s ms 20 ms 20ms 2ms 50 ms 50 ms 5 ms ‘A Sweep Only ots Os o2s 02s 08s 05s 50 ms REV SEP 1981 Performance Check Procedure—2215 Service i. Set ‘and 8 SEC/DIV 0.08 us X10 Magnifier (On (knob out) k. Select 10-ns time markers from the time-mark generator. |. Repeat parts b through hi for the A and B SEC/DIV and time-mark generator setting combinations shown in Table 4-5 under the "X10 Magnified column, 2. Check Delay Time Position Range a, Set Channel 1 AC-GNO-DC GND HORIZONTAL MODE ALT. AAND 8 SEC/OIV 0.2 ms b. Align the start of the A swoop with the Ist vertical raticue line . CHECK-Intensified portion of the trace starts wi 0.5 division of the start of the sweep. d, Rotate the B DELAY TIME POSITION control fully clockwise. ©. CHECK~Intensified zone is past the 11th vertical sraticule tine. 3. Check SEC/DIV Variable Range a. Set: CH 1 VOLTS/DIV osv Channel 1ACGND-DC DC HORIZONTAL MODE =A ASECIDIV 0.2 ms SEC/DIV Variable Fully counterclockwise X10 Magnifier Off (knob in) b. Select O.S-ms time markers from the time-mark generator. ¢. CHECK-Time markers are 1 division of less apart. d. Retum the SEC/DIV Var detent, ble control to the CAL, 474. Check Delay Time Dial Accuracy a, Set: HORIZONTAL MODE = -B ASEC/DIV 0.2 us BSEC/OIV 0.05 us 8 TRIGGER LEVEL CW-RUN AFTER DLY b. Select 0.25 time markers. «, Set the B DELAY TIME POSITION control to 1.00. ‘Adjust the Horizontal POSITION control so that the top of the first fully displayed time marker is aligned with the center vertical graticule line. 4d, Without changing the Horizontal POSITION controt setting, set the B DELAY TIME POSITION dial sotting to 00, ‘Slightly readjust the 8 DELAY TIME POSITION 39 tho top of the time marker with the center vertical graticule Tine ©. CHECK-The B DELAY TIME POSITION cial setting is between 8,87 and 9.14. f, Set: ASECIDIV 0.5 ms BSECIOIV 50 us 4, Select 0.5-us time markers. bh, Repeat parts ¢ through e. 5. Check Delay Jitter 4, Set the B SEC/DIV switch t0 0.6 ps. be. Select 10s time markers «. Slightly readjust the B DELAY TIME POSITION dial ‘0 position a time marker within the graticule area, 6. CHECK-uJitter on the leading edge of the time marker does not exceed 1 division, Disregard slow drift 6. Check POSITION Control Range a, Set A SEC/DIV rons HORIZONTAL MODE =A 48 b. Select 504s time markers, © Align the 3rd time marker with the conte- vertical sraticue line. 4d, Set the X10 Magnifier knob to On (knob out) ©. CHECK Magnified time marker can be positioned to the left of the center vertical graticue line by rotating the Horizontal POSITION control fully counterclockwise. {. CHECK-Start of the swoop can be positioned to the right of the center vertical graticule line by rotating the Horizontal POSITION control fully clockwise. 1, Disconnect the test setup. 7. Check X-Gain a, Set: CH 1 VOLTS/DIV 20mVv ASECIDIV xy b, Connect a O.1:V standard-amplitude signal to the (CH 1 OR X input connector using 2 50-92 cabl ©. CHECK-Display is 6 divisions 40.25 division (4.75 10 6.25 divisions). 4. Disconnect the test setup. 8, Check X-Bandwidth a. Connect 2 50-Hz leveled sinewave signal via a 50-2. cable and a 50-2 termination to the CH 1 OR X input ‘connector. b. Set the generator to obtain a Budivision horizontal display, cc. Adjust the generator output frequency t0 2 MHz, 4. CHECK—Display is atleast 3.5 divisions in length. «, Disconnect the test setup.Performance Check Procedure—2215 Service TRIGGERING Equipment Required (see Table 4-1): Leveled Sine-Wave Generator (Item 2) 50.2. BNC Cable (Item 4) 50-9 BNC Termination (Item 5) 10X Attenuator (Item 7) INITIAL CONTROL SETTINGS POWER cRT AUTO INTENSITY ‘AUTO FOCUS Vertical POSITION (both) VERTICAL MODE CH 1 VOLTS/DIV cH 2 VOLTS/DIV VOLTS/DIV Variable (both) INVERT AC-GND-C (both) Horizontal POSITION HORIZONTAL MODE AAND B SEC/DIV ‘AND BSEC/DIV Variable X10 Magnifier Trigger VAR HOLDOFF A TRIGGER MODE ‘SLOPE (both) LEVEL (both) A&BINT ‘A SOURCE AEXT COUPLING ON (button in} As desired Best focused display Midrange cHT 2mv 20 mv CAL detent Normal (button out) oc Midrange A 0.2 us CAL detent (Off (knob in) NORM NORM t Midrange VERT MODE INT pe BNC T-Connector (Item 8) Probe-tip-to-BNC Adapter (Item 9) P6120 Probe (provided with instrument) PROCEDURE STEPS 1, Check Internal Triggering 2. Connect the leveled sine-wave generator output via @ 50-91 cable and a 50-2 termination to the CH 1 OR X input connector. . Set the generator output to produce a 4-division, 2.MH2 display. . Set the CH 1 VOLTS/DIV switch to 20 mV. d. CHECK~Stable display can be obtained by adjusting ‘the A TRIGGER LEVEL control for each switch com: bination given in Table 4.6, Table 46 ‘Switch Combinations for A Triggering Checks ‘TRIGGER MODE TRIGGER SLOPE NORM tL NORM x AUTO X ‘AUTO Lt @, Set the HORIZONTAL MODE switch to B. 1 CHECK-Stable display can be obtained by adjusting the B TRIGGER LEVEL control for both positive: and negative-going positions of the B TRIGGER SLOPE switch. 49Performance Check Procedure-2216 Service 9. Set VERTICAL MODE cH2 HORIZONTAL MODE =A hh, Move the gonerator output from the CH 1 OR X input connector to the CH 2 OR Y input connector, Set VERTICAL MODE to CH 2. 1. Repeat parts d through Set HORIZONTAL MODE =A ASECIDIV 0.05 ys k. Set the generator to produce @ 1.5-division, GO-MHZ display. |. Repeat part a, ‘m, Move the generator output from the CH 2 OR Y input connector to the CH 1 OR X input connector, Set VERTICAL MODE to CH 1. 1, Repeat part d. ©. Adjust the generator output and the A TRIGGER LEVEL control for a stable, 2-division display. . Repeat parts e and f, 4. Move the generator output from the CH 1 OR X input connector to the CH 2 OR Y input connsctor. Set VERTICAL MODE to CH 2. Repeat part f Disconnect the test setup, 2. Check External Triggering a. Set: vouTsio1v 10 mv A SEC/DIV 104s VERTICAL MODE cHt LeveLeD SINE-WAVE GENERATOR 50-0 PROBE CABLE BNC PROBE-TIP.T0- T-CONNECTOR BNC ADAPTER 2826-108, 10x 50-0 I renntivarion Nw Figure 4-1. Tost setup for external trgger and jitter checks. 410 REV SEP 1981‘be Connect the test setup as shown in Figure 4-1, «, Set the leveled sinewave genorstor to produce a S.division, S0-kHz display. 4, Set: VERTICAL MODE. cH2 ASECIDIV O2us ‘A SOURCE ext 2. Move the signal from the CH 1 OR X input connector to the EXT INPUT connector. {, Set the generator to 2 MHz. 9. CHECK—Stable display can be obtained by adjusting the A TRIGGER LEVEL control for each switch com- bination given in Table 4.6, hh, Remove the 10X attenuator from the test setup and sot the A EXT COUPLING switeh to DC+10, i. Repeat part g REV FEB 1962 Performance Check Procedure-2216 Service i Set: VOLTS/DIV (botn) 50 mv VERTICAL MODE cHt A SECIOIV 20 us ‘A SOURCE INT , Reconnect the test setup as shown in Figure 4-1, |. Set the leveled sinewave generator to produce a S-division, 50-kH2 display. rm, Se: VERTICAL MODE cH2 ASECIDIV 0.05 us X10 Magnifier ‘On (knob out) ‘A SOURCE EXT 1. Repeat part e, ©, Set the generator to 60 MHz . Repeat parts g and h, 4. Repeat part g Disconnect the test setup.Performance Check Procedure—2215 Service EXTERNAL Z-AXIS AND PROBE ADJUST Equipment Required (see Table 4-1): Leveled Sine Wave Generator (Item 2) ‘Two 50-2 BNC Cables (Iter 4) BNC T-Connector (Item 8) P6120 Probe (provided with instrument) INITIAL CONTROL SETTINGS POWER on cRT AUTO INTENSITY As desired AUTO FOCUS. Best defined display Vertical Channel 1 POSITION. Midrange VERTICAL MODE cHT cH 1 VOLTS/OIV 2v CH 1 VOLTS/OIV Variable CAL detent Channel 1ACGND-DC DC Horizontal POSITION Midrange HORIZONTAL MODE =A ASECIDIV 20us AAND BSEC/DIV Variable CAL detent Trigger VAR HOLDOFF NORM ATRIGGER MODE AUTO A TRIGGER SLOPE St A TRIGGER LEVEL Midrange A&BINT VERT MODE ‘A SOURCE Int 412 PROCEDURE STEPS 1. Check EXT Z-AXIS Operation 2. Connect the leveled sine-wave generator output via a T-connector and two 50-2 cables to the EXT Z-AXIS INPUT connector on the rear panel and to the CH 1 OR X input connector. . Adjust the generator controls to produce a 5-volt, 0 kHz display. ©. CHECK-For noticeable intensity moduletion. The positive part of the sine wave should be of lower intensity than the negative part. dd. Disconnect the test setup. 2, Check PROBE ADJUST Operation a, Set: CHT VOLTS/DIV tomv ASECIDIV 0.5 ms b. Connect the P6120 Probe to the CH 1 OR X input ‘connector and insert the probe tip into the PROBE ADJUST jack on the instrument front panel. If necessary, adjust the probe compensation for a flat-topped square. ‘wave display. ©. CHECK-Display is § divisions #1 division (4 to 6 divisions), 4, Disconnect the test setup. REV SEP 1961Section 5~2215 Service ADJUSTMENT PROCEDURE INTRODUCTION IMPORTANT—PLEASE READ BEFORE USING THIS PROCEDURE PURPOSE The “Adjustment Procedure” is used to return the instrument to conformance with its "Performance Require: ments" as listed in the “Specification” (Section 1), These adjustments should be performed only after the checks in the “Performance Check Procedure" (Section 4} have indicated a need for adjustment of the instrument. TEST EQUIPMENT REQUIRED The test equipment listed in Table 4-1 is a complete list of the equipment required to accomplish both the "adjustment Procedure” in this section and the "Per formance Check Procedure” in Section 4. Test equipment specifications described in Table 4-1 are the minimum necessary to provide accurate results. Therefore, equipment used must meet or exceed the listed specifications. Detailed ‘operating instructions for test equipment are not given in this procedure. If more operating information is required, rafer to the appropriate test equipment instruction manual When equipment ether than that recommended is used, control settings of the test setup may need to be altered, If the exact item of equipment given as an example in ‘Table 4-1 isnot available, first check the "Purpose" column to verify use of this item, Then use the "Minimum Spec: ification” column to determine if any other available test equipment might suffice LIMITS AND TOLERANCES The limits and tolerances stated in this procedure are instrument specifications only if they are listed in the "Porformance Requirements" columa of the "Speci: cation" (Section 1), Tolerances given are applicable only to the instrument undergoing adjustment and do not include test equipment error. Adjustment of the instrument must ° be accomplished at an ambient temperature between 420°C and #30°C, and the instrument must have hed a warm-up period of at least 20 minutes, PARTIAL PROCEDURES ‘This procedure is structured in subsections to permit adjustment of individual sections of the instrument (except, the Power Supply) whenever a complete readiustment is, ‘not required, For example, if only the Vertical section fails ‘to meet the Performance Requirements (or has had repairs made or components replaced), it can be readjusted with little or no effect on other sections of the instrument. However, if the Power Supply section has undergone repairs or adjustments that change the absolute value of any. fof the supply voltages, a complete readjustment of the instrument may be required At the beginning of each subsection is a list of all the front panel control settings required to prepare the instru ment for performing Step 1 in that subsection. Each succeeding step within a subsection should then be per formed both in the sequence presented and in its entirety to ensure that control settings will be correct for ensuing steps. ADJUSTMENT INTERACTION ‘The use of Table 5-1 is particularly important if « partial procedure is performed or if a circuit requires readjustment ‘due to 2 component replacement. To use this table, first find the adjustment that was made (extreme left column), Then move to the right, across the row, until you come to darkened square, From the darkened square, move up, the table to find the affected adjustment at the heading of that column, Check the accuracy of this adjustment and, if necessary, perform readjustment. 54‘Adjustment Procedure—2218 Service Table 5-1 Adjustment Interactions Adjustments or Replacements Hade Adsustnents Affected rpc euspercea cs aeeseaas ce =8. 6 ADS HEAD ROOM VOLTAGE TRACE ROTATION RID BIAS, ASTIG ‘AUTO FOCUS ADT (GEORETRY VERTICAL CAIN = ATTENUATOR STEP_GALANCE, [ATTENUATOR X1@ BALANCE INVERT BALANCE. CH_I/CH 2 BALANCE [ATTENUATOR COMP ‘VERTICAL OUTPUT CORP CHa CH 2 He MATCH HORIZ CAIN HoRIZ-@ CAIN HORIZ_X1@_ GAIN, MAG_RECISTRAT ON DELAY OIAL_START AD DELAY _DIAC_GAIN ‘Sys TIMING (A AND) HIGH SPEED TIMING GAIN. ‘SLOPE _GALANCE ‘AUTO TRIGGER CENTERING (CRT_REPLACENENT 62Specific interactions are also called out within certain ‘adjustment steps to indicate that adjustments must be repeated until no further improvement is noted. PREPARATION FOR ADJUSTMENT It is necessary to remove the instrument cabinet perform the Adjustment Procedure. See the "Cabinet removal instructions located in the “Maintenance” section fof the manual. Before performing this procedure, do not preset any internal controls and do not change the ~8.6:V Power- Supply adjustment, since that will typically necessitate @ complete readjustment of the instrument, when only a partial readjustment might otherwise be required. To avoid ‘unnecessary readjustment, only change an internal control setting whenever s Performance Characteristic cannot be met with the original setting. If it is necessary to change the setting of any internal control, always check Table 5-1 {or possible interacting adjustments that might be required. Al test equipment items described in Table 4-1. are ‘required to accomplish a complete Adjustment Procedure, [At the beginning of each subsection there is an equipment- required list showing only the test equipment necessary for performing the steps in that subsection. In this ‘the item number following each piece of equipment cor responds to the item number listed in Table 4-1 Make initial control settings as listed at the beginning fof each subsection. Then connect the test equipment to ‘an appropriate ac-power-input source and connect the 2215 ‘to a variable autotransformer (Item 10 in Table 4-1) that is set for 115 V ac. Apply power and allow a 20-minute watm.up period before commencing any adjustments. ‘The most accurate display adjustments are made with a stable, wellfooused, low-intensity display. Unless otherwise noted, adjust the AUTO INTENSITY, AUTO FOCUS, and TRIGGER LEVEL controls as needed to view the display. Wherever possible in this procedure, instrument per formance js first checked before an adjustment is made, ‘Steps containing both checks and adjustments are titled “Gwok! Ade." Those steps with only checks ae tied Poe EV SEP 1981 Adjustment Procedure—2215 Service INDEX TO ADJUSTMENT PROCEDURE Power Supply and CRT Display Page 1, Check/Adiust Power Supply DC Levels and Ripple. « 54 2. Check High-Voltage Supply pe 5S 3. Check/Adjust CRT Grid Bias... 155 4, Adjust Astigmatism and Auto Focus Tracking... 55 5. Check/ Adjust Trace Alignment (TRACE ROTATION) : 88 6, Adjust Geometry. 002s cece 5H Vertical 1. Adjust Vertical Gain 87 2. Adjust Attenuator Step Balance. . 58 3, Adjust Attenuator X10 Balance 1158 44. Check Deflection Accuracy and Variable Range . - 5-8 5. Check Input Coupling 59 6. Check ALT and CHOP Operation. <<<... 58 7. Check VOLTS/DIV Variable Control Trace Shift 59 8, Adjust Invert Balance... Boposeoos) 9, Adjust Trigger Balance .- ce 58 10, Adjust Attenuator Compensation... - 5:10 11. Adjust Vertical Output Amplifier Compensation . .5-10 12. Adjust Channel Matching and Check Bandwidth . 5-11 18. Check Common-Mode Rejection Ratio 14. Check POSITION Control Range 15. Check Channel Isolation Horizontal 1, Adjust Horizontal Amplifier Gain. 513 2. Adjust Magnifier Registration . 513 3, Adjust Delay Dial Timing 514 4, Adjust S-us Timing . 514 5. Adjust High-Speed Timing. - 514 6. Check Timing Accuracy . 515 7. Check 8 DELAY TIME POSITION Control Range 516 8. Check SEC/DIV Variable Range 516 9, Check B DELAY TIME POSITION Dial Accuracy . : 410. Check Delay sitter 11, Cheek POSITION Control Range 12. Adjust X-Gain. « 13, Check X-Bandwidth Triggering 1. Adjust Trigger Slope Balance . 518 2. Check/Adjust Auto Trigger Centering and TRIG'D LED Operation . 518 3. Check Internal Triggering 2549 4. Check External Triggering 1519 External Z-Axis and Probe Adjust 1, Chock EXT Z-AXIS Operation. 521 2. Check PROBE ADJUST Operation 621 53‘Adjustmont Procedure—2215 Service POWER SUPPLY AND CRT DISPLAY Equipment Required (see Table 4-1) Leveled Sine Wave Generator (Item 2) ‘Time-Mark Generator (Iter 3) 50-9 BNC Cable (Item 4) 50-9 BNC Termination (Item 5) Variable Autotransformer (Item 10) See abaustwigh Locations 1 NOTE Before applying power to the 2215, make the initial control settings. Connect the 2215 to an appropriate power source through a variable autotransformer, adjusted for an output of 115 V. Apply power to both the instrament and the t3st equipment and allow a 20-minute warmup period before con- ‘mencing the adjustments and checks. INITIAL CONTROL SETTINGS cRT AUTO INTENSITY ‘AUTO FOCUS. As desired. Best focused display Vertical (both) POSITION Midrange VERTICAL MODE CHT VOLTs/DIV Orv VOLTS/DIV Variable CAL detent AC-GND-DC GND Horizontal POSITION Midrange HORIZONTAL MODE =A ASECIDIV Sus ‘AND B SEC/DIV Variable CAL detent X10 Magnifier Off (knob in} Trigger VAR HOLDOFF NORM ATRIGGER MODE TV FIELD ATRIGGER SLOPE Sf ATRIGGER LEVEL Midrange ABINT VERT MODE ‘A SOURCE, INT. 54 Digital Voltmeter (Item 11) Test Oscilloscope and 1X Probe (Item 12) DC Voltmeter (Item 13) Screwdriver (Item 14) at the back of this manual for location of test points and adjustments PROCEDURE STEPS 1. Check/Adjust Power Supply DC Levels and Ripple (R946 and R952) NOTE Review the information at the beginning of the Adjustment Procedure before starting this step. a. Remove the High-Voltage shield (see the “High: Voltage Shield" removal procedure in Section 6). WARNING ) When checking the Head Room Voltage, use @digital voltmeter that is isolated from ground, because the Inverter power-supply circuitry common is at line potential b. Connect the digital voltmeter low lead to common (TP934) and connect the volts lesd to TPS52. ©, CHECK—Reading is #4.2 V to 4.4 V, If the reading is within these limits, skip to part . 1d, ADJUST—Head Room Voltage Adjust (R952) for +43. fe, Disconnect the voltmeter leads, f. Connect the digital voltmeter low lead to chassis ground (TP5O1) and connect the volts lead to the ~8.6-V supply (TPS0O). @9. CHECK—Reading is 8.64 V to 8.56 V. If the reading is within these limits, skip to parti h, ADJUST—The -8.6-V Adj (R94) for -86 V. i. Replace the High-Voltage shield (see the “High Voltage Shield reinstallation procedure in Seetion 6). |. CHECK—Voltage levels of the remaining power supplies listed in Table 6-2 are within their specitied limits Table 52 Power Supply Limits and Ripple Power | Test Reading | PP Ripple Supply | Point (vols) (mv) asv | Te500 | -a56t-a6a| <10 vev | woes | a7sv0525 | <10 wav | wos | eases | <0 vaov | woos | 285c00158 | <6o soov | wos 95 to 105 | _<200 k. Connect the test oscilloscope, using 2 1X probe, to the first test point indicated in Table 5:2 and connect the probe ground lead to TPSO1 1. CHECK-Ripple amplitude of the de supply is within the typical value given in Table §-2 1m, Repeat parts k and I for each test point in Table 5-2 1, Disconnect the test setup. 2. Check High-Voltage Supply 1, Set the POWER switch to OFF (button out) b. Set the de voltmeter to a range of at least -2600 V de land connect the volts lead to chassis ground. Remove the crt base-socket cover and conneet the common lead of the de voltmeter to pin 2 on the socket. REV SEP 1981 ‘Adjustment Procedure 2215 Service ¢. Set the POWER switch to ON (outton in). 4. CHECK—High Vottage Supply de lavel is 1900 V to 2100. €. Set the POWER switch to OFF (button out, {. Disconnect the voltmeter leads and re-install the ort base-socket cover. 9. Set the POWER switch to ON (button in). 3. Adjust CRT Grid Bias (R860) 2, Set the A SEC/DIV switeh to XY. b. Rotate the AUTO INTENSITY control fully counter clockwise. ©, Connect a 50:2 termination to the EXT Z AXIS INPUT connector located on the rear panel 4d. ADJUST-Both the Grid Bias adjustment (R860) and the AUTO FOCUS control for a visible dot. Then back off ‘the Grid Bias potentiometer until the dot just d sappears , Disconnect the test setup. 4, Adjust Astigmatism and Auto Focus Tracking (R887 and R875) a. Set: Channel 1ACGND-DC OC ASEC/OIV 20s A TRIGGER MODE ‘AUTO b. Connect a leveled sinewave generator via a 50-2 cable and 2 50:2 termination to the CH 1 OR X input connector. €. Adjust the generator output for a 4-divsion, 50-kHz display, 55Adjustment Procedu 7215 Service 4, ADJUST—Both the Astig adjustment (R887) and the AUTO FOCUS control for the best focused display aver the range of the AUTO INTENSITY contro ©, Set the A SEC/DIV switch to 5 us 4. ADJUST—Auto Focus Adj (R875) for the best focused display. Do not change the front panel AUTO FOCUS control 1. Disconnect the test setup. 5, Check/Adjust Trace Alignment (TRACE ROTATION) ‘2, Set the Channel 1 AC-GND-DC switch to GND. b, CHECK That the trace is parallel to the center horizontal graticule line. 56 c. ADJUST—The frontpanel_ TRACE ROTATION control to align the trace with the center horizontal sraticule line 6. Adjust Geometry (R870) a, Set: cH 1 VOLTS/DIV s0mv Channel 1AC-GND-DC DC b. Connect 504is time markers from the time-mark generator via a 60-92 cable and a 80-2 termination to the (CH 1 OR X input connector ©. Adjust the A AND B SEC/DIV Variable centrol for ‘5 markers per division, 4d, ADJUST-Geom (R870) for minimum curvature of ‘the markers across the graticule area, , Disconnect the test setup. REV SEP 1981‘Adjustment Procedure—2215 Service VERTICAL Equipment Required (see Table 4-1): Calibration Generator (item 1) Leveled Sine-Wave Generator (Item 2) 50-9 BNC Cable (Item 4) 50-9 BNC Termination (Item 5) Dual-Input Coupler (Item 6) 10X Attenuator (Item 7) Adapter (Item 9) Digital Voltmeter (Item 11) 1% Probe (Item 12) Screwdriver (Item 14) Low-Capacitance Alignment Too! (Item 15) P6120 Probe (Included with instrument) See ADJUSTMENT LOCATIONS 1 and ADJUSTMENT LOCATIONS 2 at the back of this manual for locations of test points and adjustments, INITIAL CONTROL SETTINGS POWER (ON (button in} cRT AUTO INTENSITY As desired ‘AUTO FOCUS Best focused display Vertical (both) POSITION Midrange VERTICAL MODE cHT VOLTS/DIV 20mv VOLTS/DIV Variable CAL detent INVERT Normal (button out) AC-GND-DC. De Horizontal POSITION Midrange HORIZONTAL MODE A AAND B SEC/DIV 0.5 ms AAND 8 SEC/DIV Variable CAL detent X10 Magnifier Off (knob in} Trigger VAR HOLDOFF NoRM A TRIGGER MODE AUTO A TRIGGER SLOPE St A TRIGGER LEVEL, Midrange A&BINT VERT MODE ASOURCE INT PROCEDURE STEPS 1. Adjust Vertical Gain (R186, R286, R145, and R245) a. Connect @ 100-mV standarcamplitude signal via a 50-82 cable to the CH 1 OR X input connector. b. ADJUST—Ch 1 Gain (R186) for an exact Sdivision display, c, Move the cable from the CH 1 OR X input connector to the CH 2 OR Y input connector. Change the VERTICAL MODE switch to CH 2. 4. ADJUST—Ch 2 Gain (R286) for an exact S-division display fe. Change the generator output to 10 mV and set the (CH 1 and CH 2 VOLTS/DIV switches to 2 mV. £. ADJUST-Ch 2 X10 Vert Gain (R245) for an exact S.division display, {2. Move the cable from the CH 2.OR Y input connector to the CH 1 OR X input connector. Change the VERTICAL MODE switch to CH 1 h, ADJUST-Ch 1 X10 Vert Gain (R145) for an exact S.division display. 57Adjustment Procedure-2215 Service 2. Adjust Attenuator Step Balance (R138 and R238) 2, Set both AC-GND-DC switches to GND. b. Set the CH 1 VOLTS/DIV switch to 10 mV and position the trace on the center horizontal graticule line using the Channel 1 POSITION control {. Change the CH 1 VOLTS/DIV switch to 2 mV. 4d. ADJUST—Ch 1 Step Bal (R138) to set the trace on the center horizontal graticule line ©. Repeat parts b through d until there is no trace shift when changing the CH 1 VOLTS/DIV switch from 10 mV to2mV, f Change the VERTICAL MODE switch to CH 2. 4g. Repest parts b through e for Channel 2, adjusting Ch 2 Step Bal (R238) in step d. 3. Adjust Attenuator X10 Balance (R146 and R246) 4, Set the CH 2 VOLTS/DIV switch to 20 mV. b, Position the trace on the center horizontal graticule line using the Channel 2 POSITION control ce. Change the CH 2 VOLTS/DIV switch to 10 mV. 4d, ADJUST-Ch 2 X10 Bal (R246) to set the trace on the center horizontal graticule line @, Repeat parts a through d until there is no trace shift ‘whan changing the CH 2 VOLTSIDIV switch from 20 mV 10 10 my, 4, Change the VERTICAL MODE switch to CH 1 3, Repeat parts a through ¢ for Channol 1, adjusting (Ch 1 X10 Bal (R146) in step d 58 4. Check Deflection Accuracy and Variable Range a. Set CH 1 VOLTS/DIV amv CH 2 VOLTS/DIV 10v AC-GND.DC (both) pe b, CHECK-Deflection accuracy is within the limits siven in Table 5-3 for each CH 1 VOLTSIDIV switch set ting and corresponding standard-amplitude signal. When at the 20-mV VOLTS/DIV switch setting, rotate the CH 1 VOLTS/DIV Variable control fully counterclockwise and CHECK that the display decreases to 2 divisicns or les. ‘Then return the VOLTS/DIV Variable control to the CAL dotent and continue with the 50-nV check, Table 5:3 Deflection Accuracy Limits voursow | Sanwa | versa | Stamey Sting | “Sana | (Owsiond | (tion) mom | anv o | 4a5 516 conv | av 4 | seateai2 ov 1 5 [a 055 ieee a | see t04.12 W Sv 5 | 485 06.6 Ova oa 5 | 4s5t05.16 «, Set the VERTICAL MODE switch to CH 2and move the eable from the CH 1 OR X input connector to the CH 2 OR Y input connector. d. CHECK-Deflection accuracy is within the timits given in Table 63 for each CH 2 VOLTS/DIV switch set- ‘ting and corresponding standard-amplitude signal. Perform the checks from the bottom to the top of Tasle 5-3 to avoid unnecessary switch-position changes. When at the 20mV VOLTSIDIV switch setting, rotate the CH 2 VOLTSIDIV Variable control fully counterclockwise and CHECK that the display decreases to 2 divisions or less. REV SEP 1981‘Then return the VOLTS/DIV Variable control to the CAL. detent and finish the check. 5. Check Input Coupling a. Sot both VOLTS/DIV switches to 50-mV. b. Set the callbration generator to produce a 200.mV standard-ampltude signal ©, Position the bottom of the signal on the center hor zontal graticule ine sing the Channel 2 POSITION control. 4, Set the Channet 2 input coupling switch to AC. ¢. CHECK-Display is centered about the center hori- zontal graticule line f. Sot the VERTICAL MODE switch to CH 1 and move ‘the input signal from the CH 2 OR Y input connector to the CH 1 OR X input connector. '9, Repeat parts ¢ through @ for Channel 1. 6. Check ALT and CHOP Operation a, Set: VERTICAL MODE BOTHALT AC.GND.DC (both) GNO ASECIDIV 10ms bb. CHECK—Display alternates betweon the CH 1 and CH 2 displays. If necessary, use both POSITION controls ‘to separate the two traces. «©, Set VERTICAL MODE to CHOP. 4d. CHECK-CH 1 and CH 2 displays are both displayed simultaneously, 7. Check VOLTS/DIV Variable Control Trace Shift a, Set: VERTICAL MODE cHt VOLTS/DIV (both) 2mv AC-GND-DC (both) be ASECIDIV| 0.2 ms REV SEP 1981 ‘Adjustment Procedure—2215 Service . Center the trace on the center horizontal graticule line using the Channel 1 POSITION control ©. Rotate the CH 1 VOLTS/DIV Variable control ‘counterclockwise through its full range. d. CHECK—That the trace does not shift more than 2.5 divisions, @. Return the CH 1 VOLTS/DIV Variable control to ite CAL detent. f, Set the VERTICAL MODE switch to CH 2. 9. Repeat parts b through e for CH 2. 8. Adjust Invert Balance (R264) Set the CH 2 VOLTS/DIV switch to 20 mV. 'b, Center the trace on the center horizontal graticule line using the Channel 2 POSITION control , Push in the INVERT button, 4d. ADJUST—Invert Bal (R264) to position the trace ‘on the center horizontal graticule line. e. Return the INVERT button to Normal (button out). 4. Repeat parts ¢ through ¢ until there is no trace shift when switching the INVERT button between Invert and Normal 9. Adjust Trigger Balance (R154) a, Set the A & B INT switch to CH 2. b. Connect the digital voltmeter low lead to chassis ground (TP5O1) and the volts lead to pin 16 of U421; note the voltage reading for use in part d. «, Set the A & B INT switch to CH 1 4, ADJUST-—Ch 1/Ch 2 Balance (R154) so that the voltage reading is the same as that obtained in part b. 59Adjustment Procedure—2215 Sorvice €, Disconnect the test setup. 10. Adjust Attenuator Compensation (C105, C104, C111, C110, C205, C204, C211, and C210) a. Set: cH 1 VOLTS/DIV 20mv AG-GND.DC (both) be ASEC/DIV 0.2 ms b. Connect a 1-kHz, high-amplitude square wave via 50-62 termination, a probe-tip-o-bne adapter, and a P6120 Probe to the CH 1 OR X input connector. ©. Set the generator output to produce a Sdivision display and compensate the probe using the probe com- pensation adjustment (see the probe instruction manual) 6, Set the CH 1 VOLTS/DIV switch t0 0.2 V. 2, Replace the probe and probettip-to-bne adapter with 250-2 cable, {Adjust the generator output for a S-division display. NOTE Use Table 54 to identify the correct capacitor for ‘each channel adjustment. 9. ADJUST=The #10 LF Comp capacitor for best front Table 5.4 Attenuator Compensation Adjustments Adjustment Channel 1 Channel 2 10LF Comp C105 205, #10 Input © 108 204) +100 LF Comp cn cnt 100 Input C e110 210 h. Replace the cable and 50-2 termination with the P6120 Probe and probe-tip-to-bne adapter. |, Adjust the gonerator output for a S-division display 5-10 J, ADJUST—The +10 Input C capacitor for best flat top. k. Repeat parts @ through j until no further improve- ment is noted, Add the 50:2 termination to the cable in part. |. Set the CH 1 VOLTS/DIV switch 10 2.V. 1m. Replace the probe and probe-tip-to-bne adapter with the 60-2 cable. 1. Adjust the generator output for a Sdivision display. ©, ADJUST-The #100 LF Comp capacitor for best front corer. P. Replace the 50: cable with the probe and probe: tiptorbne adapter. 4. Adjust the generator output to produce a display as close as possible to 5 divisions. 1. ADJUST—The +100 Input C capacitor for best flat top. s. Repeat parts m through until no further improve: ment is noted, 1. Set the VERTICAL MODE switch to CH 2. 1, Repeat parts b through s for CH 2. v. Disconnect the test setup. 11. Adjust Vertical Output Amplifier Compen- sation (R357, C357, R367, R366, and C366) a, Set: VOLTSIDIV (both) ASECIDIV 20 mv 0.08 us b. Connect a 1:MH2, positive going fast-rise square-wave via a 80-92 cable, a 10X attenuator, and a 60-2 termination to the CH 2 OR ¥ input connector,. Adjust the generator output for a Sdivision display. 4, Preset High Freq Comp clockwise, (R357) fully counter: @, ADJUST-High Freq Comp (C357) until ringing just disappears on the Front corner. {. ADJUST—Low Freq Comp (R367) and Mid Freq Comp (R366 and C366) for best flat top beyond 20 ns from the corner. 9. ADJUST-R357 and C357 for best corner on the first 20 ns of the displayed signal hh, Repeat parts f and g until no further improvement is notes. i. Set the CH 2 VOLTS/DIV switch to 0.1 V and repeat parts f and g for best compromise with the 200m VOLTS) DIV switeh setting, |. Disconnect the tost setup. 12. Adjust Channel Matching (C167) and Check Bandwidth a, Sex: VOLTS/DIV (both) 20mv ASECIDIV 20s b. Connect the loveled sineavave generator output via ‘2 60:9 cable and 2 50-9 termination to the CH 2 OR Y input connector, . Set the generator output for a Sivision, SOkH2 display. 4d, Increaso the generator frequency until the display reduces to 3.5 divisions , Move the signal from the CH 2 OR Y input connector to the CH 1 OR X input connector, Set the VERTICAL, MODE switch to CH 1 f ADJUST-CH 1 & CH 2 HF Match (C167) for 2 vertical display amplitude of 3.8 divisions @ Adjustment Procedure-2215 Service 49. Set both VOLTS/DIV switches to 2 mV. h. Connect the leveled sinewave generator output via 2 50-2 cable and a 502 termination to the CH 1 OR X input connector. i. Set the generator output amplitude for a S-division, 50-kHe display. j. Change the generator output frequency to the value shown in Table 55 for the corresponding VOLTS/DIV switch setting Table 55 Settings for Bandwidth Checks VoLTs/DIV Switch Settings Generator Output Frequency 2mV to 10mV 50 MHz 20 mV t0 10 60 MHz k, CHECK—Display amplitude is 3.6 divisions or groater |. Repeat parts i through k for all indicated CH 1 VOLTS/DIV switch settings, up to the output-voltage upper limit of the sine-wave generator being used, m, Move the generator output signal from the CH 1 OR X input connector to the CH 2 OR Y input connector. Set the VERTICAL MODE switch to CH 2. 18, Repeat parts i through k for all indicated CH 2 VOLTS/DIV switch settings up to the outputvoltage upper limit of the sinewave generator being used. ©. Disconnect the test setup. 13. Check Common-Mode Rejection Ratio a. Set both VOLTS/DIV switches to 20 mV. b. Connect a 10-MHz, leveled sinewave signal via a 50-82 cable, 8 5082 termination, and a dual-input coupler to the CH 1 OR X and the CH 2.OR Y input connectors . Set the generator output amplitude to produce a division display. 511‘Adjustment Procedure—2215 Service 4, Vertically center the display using the Channel 2 POSITION control, Then set VERTICAL MODE to CH 1 and vertically center the display using the Channol 1 POSITION control, , Set the VERTICAL MODE switches to BOTH and ‘ADD; then push in the INVERT button. £. CHECK—Display amplitude is 0.6 division or less 49, If the check in part € meets the requirement, skip to part n. If it does not, continue with part, hh, Set VERTICAL MODE to CH 1. |. Change the generator frequency to 50 kHz and adjust the output to obtain a 6-division display. j. Set VERTICAL MODE to BOTH, k, Adjust the CH 2 VOLTS/DIV Variable control for ‘minimum display amplitude (best CMRR). |. Change the generator frequency to 10 MH. m, CHECKDisplay amplitude is 0.6 division or less 1. Disconnect the test setup, 14, Check POSITION Control Range 2. Set: VERTICAL MODE cut VOLTS/DIV (both) 50 mv AC-GND.0C (both) aC . Connect a 0.5:V standard-amplitude signal via a 50-2 cable to the CH 1 OR X input connector. . Adjust the CH 1 VOLTS/DIV Variable control for a 4-civision display. Then set the CH 1 VOLTS/DIV switch to 10 mV. 512 4d, CHECK—Rotating the Channel 1 POSITION control fully counterclockwise positions the top of the trace below ‘the center horizontal graticule line, @. CHECK-Rotating the Channel 1 POSITION control fully clockwise positions the bottom of the trace zbove the center horizontal graticule line, 4. Move the signal from the CH 1 OR X input connector to the CH 1 OR X input connector to the CH 2 OR Y input ‘connector and set the VERTICAL MODE switch to CH 2. ‘9. Repeat parts c through e for Channel 2. h. Disconnect the test setup. 15. Check Channel Isolation a. Set: CH 1 voLTsiDIV osv (CH2 VOLTSIDIV 10mv VERTICAL MODE cHt b. Connect a 10-MHz leveled sine-wave signal via a 50-0 cable and a 50-2 termination to the CH1ORX input connector. c. Adjust the generator output for an 8-division input connector. 4. Set the VERTICAL MODE switch to CH 2. . CHECK.Display amplitude is 4 divisions or ess. 1. Move the input signal from the CH 1 OR X nput con- rector to the CH 2 OR ¥ input connector 9. Set cH IVoLTSiDIV to mv CH2 VOLTS/DIV osv VERTICAL MODE cH1 h. CHECK Display amplitude is 4 divisions o: less. |. Disconnect the test setup. EY SEP 1981Adjustment Procedure—2218 Service HORIZONTAL Equipment Required (see Table 4-1) Calibration Generator (Item 1) ‘Two 50-2 BNC Terminations (Item 8) Leveled Sine Wave Generator (Item 2) Screwdriver (Item 14) Time Mark Generator (Item 3) Low-Capacitance Alignment Tool (Item 15) Two 50-9 BNC Cables (Item 4) ‘See ADJUSTMENT LOCATIONS 1 and ADJUSTMENT LOCATIONS 2 at the back of this manual for test point and adjustment locations. INITIAL CONTROL SETTINGS PROCEDURE STEPS PoweR ON (button in) 1. Adjust Horizontal Amplifier Gain (R752, R682, and R733) cRT a. Connect 0.1-ms time markers from the time:mark ‘generator via @ 50-9 cable and a 50-2 termination to the EE el CH 1 OR X input connector. Connect the generator Trigger uTO COCs) Best focused display ‘output via @ 50-9 cable and a 50-9 termination to the EXT. INPUT connector. Vertical Channel 1 POSITION Midrange b. ADJUST—Horiz Gain (R752) for 1 time marker per VERTICAL MODE cH1 division CH 1 VOLTS/DIV sv cH 1 VoLTSiDIV Variable CAL detent «. Set the HORIZONTAL MODE switeh to B. INVERT. Normal (button out) Channel 1AGGND-DC DC Channel 2AGGND-DG GND 4d. ADJUST—B Gain (RGB2) for 1 time marker per division Horizontal POSITION Midrange «, Set the HORIZONTAL MODE switch to A. HORIZONTAL MODE =A AAND BSEC/DIV 0.1 ms A AND BSEC/DIV {Set the X10 Magnifier on (knob out) and select 10s Voriable CAL detent time markers from the time-mark generator. X10 Magnifier Off (knob in} B DELAY TIME POSITION 1.00 8. ADJUST-X10 Gain (R733) for 1 time marker per division, Trigger VAR HOLOOFF ROnM 2. Adjust Magnifier Registration (R758) ATRIGGER MODE AUTO 2. Select 0.5:ms time markers from the time-mark SLOPE (both) L generator and set the X10 Magnifier off (knob in) LEVEL (both) Midrange A&B INT VERT MODE ‘A SOURCE EXT b. Position the middle time marker to the center vertical AEXT COUPLING DcH10 raticule line using the Horizontal POSITION control. @ 5.13Adjustment Proceduro—2215 Service . Set the X10 Magnifier on (knob out) 4d. ADJUST—Mag Registration (R758) to position the riddle time marker on the conter vertical gratieule line, fe, Set the X10 Magnifier off (knob ia) f. CHECK—There is no discernable shift in the time ‘marker when switching between X10 Magnifier on and X10 Magnifier off @. Turn the X10 Magnifier on (knob out) and repeat parts b through e until no further improvement is noted, 3. Adjust Delay Dial Ti a. Set ing (R659 and R654) HORIZONTAL MODE ALT ASECIDIV 0.1 ms BSECIDIV tas X10 Magnifier Off (knob in} b, Select O.t-ms time markers from the time-mark generator and verify that the B DELAY TIME POSITION control is set to 1.00. ©. ADJUST—Delay Dial Start Adj (RGBB) so that the 2nd A:sweep time marker is intensified and the B-swoep time marker starts at the beginning of the B sweep, 4, Set the B DELAY TIME POSITION control to 9.00. fe. ADJUST-Delay Dial Gain (R654) so that the 10th A-swoep time markor is intensified and the B:sweep time marker starts at the boginning of the B sweep. 4, Set the B DELAY TIME POSITION control to 1.00 and repeat parts ¢ through e until no further improvement is noted, 4, Adjust 5-us Timing (C676 and C626) a. Set: HORIZONTAL MODE = -B AND B SEC/DIV Bus b, Select Sus time markers from the time-mark generator. c. ADJUST—5 us Timing (C676) for 1 time marker per division across the graticule area. 4d, Set the HORIZONTAL MODE switch to A , ADJUST-5 us Timing (C626) for 1 time marker per division aeross the graticule area, 5. Adjust High-Speed Timing (C754, C774, C784, and C734) a. Set the A SECIDIV switch t0 0.05 us be, Select 50-ns time markers from the. time-mark generator, ©. ADJUST-60 ns Linearity (C754) for equaly spaced ‘time markers atthe start of the sweep, 4. Set the X10 Magnifier on {knob out) and s#lect 10.ns time markers from the time-mark generator. NOTE In the next part, keep the adjustment screws for C774 and C784 as close to the same langth as possible, e, ADJUST-5 ns Timing (C774 and C784) alternately for one time marker every 2 divisions over the center & divisions of the magnified sweep. 4. Adjust the Horizontal POSITION control so that the 5th time marker is aligned with the 2nd vertical graticule line. 9. ADJUST-5 ns Linearity (C734) for one time marker every 2 divisions over the center 8 divisions of the mag: nified swoop, Adjust the Horizontal POSITION control to check the linearity to the 15th time marker. h, Repeat parts e through g until no further improve: ment is noted i. Set the X10 Magnifier off (knob in) and recenter the trace using the Horizontal POSITION control j, Repeat parts b through i until ne further improve: ment is noted,6. Check Timing Accuracy ‘a Select Ons time markers from the time-mark ‘generator. , Use the Channel 1 POSITION contro! to center the trace vertically. Adjust the A TRIGGER LEVEL control for a stable, triggered display . Use the Horizontal POSITION control to align the first time marker that is 60 ns beyond the start of the sweep with the 2nd vertical graticule line NoTE When making timing measurements, use as a reference the same point on each time marker. 4. CHECK—Timing accuracy is within the limits shown in Table 56 for the applicable position of the X10 Mag- nifier, When making the check with the X10 Magnifier On, ‘exclude any portion of the sweep past the 100th magnified division ®, Set the HORIZONTAL MODE switch to B and adjust the B TRIGGER LEVEL control for a stable display. 1. Align the first time marker that is 50 ns beyond the start of the sweep with the 2nd vertical graticule fine, using the Horizontal POSITION control 9 CHECK Timing accuracy is within the limits shown in Table 6-6 for the applicable position of the X10 Mag- nifier. When making the check with the X10 Magnifier On, exclude any portion of the sweep past the 100th magnified division, h, Set the HORIZONTAL MODE switeh to A. |. Repeat parts b through h for the A and B SEC/DIV and timesmark generator setting combinations shown in ‘Table 5-7 under the “Normal” column, i, Set: ‘and B SEC/DIV 0.05 us X10 Msgnifier On (knob out) REV SEP 1981 Adjustment Procedure~-2215 Service k, Select ‘generator, 10-ns time markers from the time-mark |. Repeat parts b through h for the A and B SEC/DIV and timesmark generator setting combinations shown in Table 5-7 under the "X10 Magnified” column, Table 56 And 8 Timing Accuracy X10 Magnifier | Accuracy st 10th Vertical Gretiule Line Ort tknodiny) | 3 (0.28dWvision) (On {knob out) 5% (0.40 division) Table 5-7 Settings for Timing Accuracy Checks AANDB. Mark Generator Output SEC/DIV ——__ ‘Switch Setting Normal | X10 Magnified 0.05 us 60 ns 10s Ot ys Ot us 10 ns 024s O.2us 20 ns O8us 0.5 us 50ns Vas tus Ot us 2us 2us O2us Bus Sus 06 us 10 ps 10s tas 20s 20s 2us 50 ys 50 ys Sus 0.1 ms 0.1 ms 104s 0.2 ms 0.2 ms 20 us 0.5 ms 05 ms 50 us ams tims ol ms 2ms 2ms 02ms Bms Sms 05 ms 10ms 10 ms ms 20 ms 20ms 2ms 50 ms 50 ms 5 ms ‘A Sweep Only ots ats 10ms 02s 02s 20ms 055 08s 50 ms 515Adjustment Procedure 2216 Service 7. Check B DELAY TIME POSITION Control Range a. Set Channel 1 AC-GND-DC GND HORIZONTALMODE ALT AAND 8 SEC/DIV 0.2 ms b, Align the start of the A sweep with the Ist vertical sraticule line, ©. CHECK-Intensified portion of the trace starts within 0.8 division of the start of the sweep, d, Rotate the 8 DELAY TIME POSITION control fully clockwise ©. CHECK-Intensified zone is past the 11th vertical araticule line 8. Check SEC/DIV Variable Range a. Set: CH 1 VOLTS/DIV os Channel 1 AC-GND-DC_ DC HORIZONTALMODE =A ASECIDIV 0.2 ms SEC/DIV Variable Fully counterclockwise X10 Magnifier Off {knob in} b, Select O.S-ms time markers from the time-mark generator, , CHECK—Time markers are 1 division or less apart, 4d, Retum the SEC/DIV Variable control to the CAL, detent. 9, Check B DELAY TIME POSITION Dial Accuracy a, Set HORIZONTALMODE = ASECIDIV O2us BSEC/DIV 0.05 us B TRIGGER LEVEL, CW-RUN AFTER DLY b. Select 0.2-us time markers 516 ¢. Sot the B DELAY TIME POSITION control to 1.00. Adjust the Horizontal POSITION control so that the top of the first fully displayed time marker is aligned with the center vertical graticule line 4. Without changing the Horizontal POSITION contro! setting, sot the B DELAY TIME POSITION dial setting to 9.00. Slightly readjust the B DELAY TIME POSITION control to align the top of the time marker with the center vertical graticule line fe. CHECK—The B DELAY TIME POSITION dial is between 8,87 and 9.14, f, Set: ASECIDIV 0.5 ms BSECIDIV 50 us 9, Select 0.6-us time markers, fh, Repeat parts ¢ through e, 10. Check Delay Jitter a, Sot the B SEC/DIV switch to 0.5 us. b. Select 10s time markers. ©. Slightly readjust the 8 DELAY TIME POSITION ial to position a time marker within the graticule area 6. CHECK-uJitter on the leading edge of the time marker does not exceed 1 division. Disregard slow drift, 11, Check POSITION Control Range a, Set: ASECIDIV tous HORIZONTAL MODE =A. b, Select 50s time markers . Align the 3rd time marker with the center vertical sgraticule line, 4. Set the X10 Magnifier knob to On (knob out)@. CHECK—Magnitied time marker can be positioned to the left of the center vertical graticule line by rotating the Horizontal POSITION control fully counterclockwise, f, CHECK-Start of the sweep can be positioned to the right of the conter vertical graticule line by rotating the Horizontal POSITION control fully clockwise, 4. Disconnect the test setup, 12. Adjust X-Gain (R709) a, Set: CH 1 VOLTS/DIV 20mv ASECIDIV xY b, Connect a O.1:V standard-amplitude signal to the (CH 1 OR X input connector using a 50-2 cable Adjustment Procedure—2215 Service ©. ADJUST-% Gain (R708) for exactly 5 divisions of horizontal deflection. 4, Disconnect the test setup, 13. Check X-Bandwidth a, Connect a 50-kHz leveled sine-wave signal via a 502 cable and a 502 termination to the CH 1 OR X input connector. b. Set the generator 10 obtain a Sdivision horizontal display «. Adjust the generator output frequency to 2 MH. 4d, CHECK-Display is at least 38 divisions in length. @, Disconnect the test sotup, 5.17Adjustment Procedure 2215 Service TRIGGERING Equipment Required (see Table 4-1): | at the back of this manual for test point and adjustment locaticns. INITIAL CONTROL SETTINGS PROCEDURE STEPS POWER (ON (button in) 1. Adjust Trigger Slope Balance (R482) a. Connect the leveled sine-wave generator ourput via @ 50-2 cable and a 50-2 termination to the CH 1 OR X CRT input connector. ‘AUTO INTENSITY As desired ete cocee: lees b, Adjust the generator output for # 50-kHz, S-division display, Vertical (both) c. ADJUST-Slope Bal (R482) for a positive vertical POSITION Midrange shift of 0.15 division at the sweep start when changing the VERTICAL MODE cHI A TRIGGER SLOPE switch from" to J VoLTs DIV. 20mv VOLTS/DIV Variable CAL detent INVERT Normal (button out) 2. Check/Adjust Auto Trigger Centering (R511 AC-GND-DC oc and R512) and TRIG‘D LED Operation a. Set: A TRIGGER LEVEL Fully clockwise Horo A TRIGGER SLOPE POSITION. Midrange HORIZONTAL MODE =A AAND B SEC/DIV 20s 'b, Adjust the generator output for a 1-division display. AAND B SEC/DIV Variable CAL detent X10 Magnifier Off knob in} ©. ADJUST-(+) Auto (R511) s0 that the display just ‘riggers on the positive peak of the signal Trigger oe VAR HOLDOFF NORM A TRIGGER MODE AUTO A TRIGGER LEVEL Fully counterclockwise SLOPE (both) ae A TRIGGER SLOPE XM LEVEL (both) Midrange AR BINT VERT MODE A SOURCE INT 2, ADJUST-(-) Auto (R512) so that the display just AEXT COUPLING oc triggers on the negative peak of the signal 5.181. Set A TRIGGER MODE to NORM, 9. CHECK—TRIG‘D LED is illuminated when a stable display is present and is off when the display is not triggered, 3. Check Internal Triggering 4, Set the CH 1 VOLTS/DIV switch to 2 mV. , Set the generator output to produce a 4-divsion, 2.MHe display, ©, Set the CH 1 VOLTS/DIV switch to 20 mv. 4, CHECK~Stable display can be obtained by adjusting the A TRIGGER LEVEL control for each switch com- bination given in Table 58, Toble 58 ‘Switch Combinations for A Triggering Checks ‘TRIGGER MODE TRIGGER SLOPE. NORM fe NORM XL AUTO x AUTO 7 €, Set the HORIZONTAL MODE switch to B. f. CHECK-Stable display can be obtained by adjusting the B TRIGGER LEVEL control for both positive- and rnegative-going positions of the B TRIGGER SLOPE switch 9. Set: VERTICAL MODE cH2 HORIZONTAL MODE =A hh, Move the generator output from the CH 1 OR X Input connector to the CH 2 OR Y input connector. Set VERTICAL MODE to CH 2. i, Repeat parts d through f. REV SEP 1981, ‘Adjustment Procedure—2215 Service Set: HORIZONTALMODE =A ASECIDIV 0.05 as k, Set the generator to produce a 1.S-division, 60-MH2 display, |. Repest part a. 1m, Move the generator output from the CH 2 ORY input connector to the CH 1 OR X input connector. Set VERTICAL MODE to CH 1 'n, Repeat part d ©. Adjust the generator output and the A TRIGGER LEVEL control fora stable, 2division display. . Repeat parts e and f 4a. Move the generator output from the CH 1 OR X input connector to the CH 2 OR Y input connector. Sot VERTICAL MODE to CH 2. 1. Repeat part f. Disconnect the test setup. 4, Check External Triggering 2, Set: VOLTS/OIV (both) 10mv ASECIDIV 104s VERTICAL MODE CHT b. Connect the test setup as shown in Figure 4-1. . Set the leveled sinewave generator to produce a Sdivision, 50-kHz display. 4. Sot: VERTICAL MODE cH ASEC/DIV 02s ‘A SOURCE ext‘Adjustment Procedure—2215 Service ‘@. Move the signal from the CH 1 OR X input connector k, Reconnect the test sotup as shown in Figure 4-1 to the EXT INPUT connector |. Set the leveled sinewave generator to produce @ Sdlivision, 50H2 display. Set the generator to 2 MHz rm. Sot: 4. CHECK-Stable display can be obtained by adjusting VERTICAL MODE cHe the A TRIGGER LEVEL control for each switch com: ASEC/DIV 0.08 us bination given in Table $8. X10 MAGNIFIER, (On (knob out) ‘A SOURCE ext h, Remove the 10X attenuator from the test setup and set the A EXT COUPLING switch to DC#10. Repeat part e ©, Set the generator to 60 MHz. 1. Repeat part g . Repeat parts g and h i. Sets VOLTS/DIV (both) 50 mv @. Repeat part VERTICAL MODE CHT A SECIDIV 204s Neotece int 1. Disconnect the test setup, 5:20 ACV SEP 1981Adjustment Procedure—2215 Service EXTERNAL Z-AXIS AND PROBE ADJUST Equipment Required (see Table 4-1): Leveled Sine Wave Generator (Item 2} ‘Two 60-8 BNC Cables (Item 4) INITIAL CONTROL SETTINGS POWER cRT AUTO INTENSITY ‘AUTO FOCUS Vertical ‘Channel 1 POSITION VERTICAL MODE (CH 1 VOLTS/DIV CH 1 VOLTS/DIV Variable Channel 1 AC-GND-0C Horizontal POSITION HORIZONTAL MODE ASECIDIV ‘AND B SEC/DIV Variable Trigger VAR HOLDOFF ATRIGGER MODE ATRIGGER SLOPE ATRIGGER LEVEL, A&BINT ASOURCE REV SEP 1961 on As desired Bost defined display Midrange cHt av CAL detent oc Midrange A 20s CAL detent NORM AUTO a Midrange VERT MODE INT BNC T-Connector (Item 8) P6120 Probe {provided with instrument) PROCEDURE STEPS 1. Check EXT Z-AXIS Operation a. Connect the leveled sinewave generator output via a T-connector and two 50-M2 cables to the EXT Z-AXIS INPUT connector on the rear panel and to the CH 1 OR X input connector. . Adjust the generator controls to produce @ 5-volt, 50 kHz display. ©. CHECK—For noticeable intensity modulation, The positive part of the sine wave should be of lower intensity ‘than the negative part. 4, Disconnect the test setup. 2. Check PROBE ADJUST Operation a. Set cH 1 VOLTS/DIV 10 mv ASECIDIV 0.5 ms 'b. Connoet the P6120 Probe to the CH 1 OR X input connector and insert the probe tip into the PROBE ADJUST jack on the instrument front panel. If necessary, adjust the probe compensation for a flattopped square wave display, ¢. CHECK-Display is § divisions 41 division (4 to 6 divisions), 4, Disconnect the test setup. 521Section 62215 Service MAINTENANCE ‘This section of the menual contains information for conducting preventive maintenance, troubleshooting, and corrective maintenance on the 2215 Oscilloscope. STATIC-SENSITIVE COMPONENTS ‘The following precautions are applicable when per forming any maintenance involving internal access to the instrument, caurion § Static discharge can damage any. semiconductor ‘amponent inthis instrument. This instrument contains electrical components that are susceptible to damage from static discharge, Table 6-1 lists the relative susceptibility of various classes of semi- conductors. Static voltages of 1 kV to 30 kV are common in unprotected environments. When performing maintenance observe the following precautions to avoid component damage: 1, Minimize handling of static sensitive components. 2, Transport and store statie-sensitive components or assemblies in their original containers or on a metal ral Label any package that contains static sensitive components or assemblies. 3, Discharge the static voltage from your body by ‘wearing @ grounded antistatic wrist strap while handling these components, Servicing static-sensitive components or assemblies should be performed only at a static-free work station by qualified service personnel. 4, Nothing capable of generating or holding 2 static charge should be allowed on the work station surface, 5, Keep the component leads shorted together whenever possible, 6, Pick up components by their bodies, never by their leads, Table 6-1 Relative Susceptibility to Statie-Discharge Damage Semiconductor Classes MOS or CMOS microcircuits or discretes, or linear mierocircuits with MOS inputs __(Most Sensitive) 1 ECL 2 Schottky signal diodes 3 Schottky TTL | 4 High-frequency bipolar transistors 8 SFT 6 Linear microcireuits 7 Low-power Schottky TTL 8 1 (Least Sensitive) 8 Voltage equivalent for level (voltage discharged from 1000F capacitor through a resitance of 100 £1) O0te500V 4-500 17» 400 %0 1000 V (est) 26200t0500V 5=400t0600V 8-900 3=250V 600% 900V 9= 1200 61Maintenance~2215 Service 7. Do not slide the components over any surface. 8, Avoid handling components in areas that have a floor for worksurface covering capable of generating a static charge, 9, Use asolderingiron that is connected to earth ground, 10. Use only approved antistatic, vacuum-type desolder- ing tools for component removal. PREVENTIVE MAINTENANCE INTRODUCTION Preventive maintenance consists of cleaning, visual inspection, lubrication, and checking instrument Performance. When accomplished regularly, it may provent instrument malfunction and enhance instrument reliability The severity of the environment in which the instrument is Used determines the required frequency of maintenance. An appropriate time to accomplish preventive maintenance is just before instrument adjustment. GENERAL CARE The cabinet minimizes accumulation of dust inside the Instrument and should normally be in place when operating the 2215. The optional frontpanel cover provides both dust and damage protection for the front panel and crt face, and it should be in place whenever the instrument is stored or is being transported, INSPECTION AND CLEANING ‘The instrument should be visually inspected and cleaned 15 often as operating conditions require, Accumulation of dirt in the instrument can cause overheating and com: onent breakdown, Dirt on components acts as an ingulating blanket, preventing efficient heat dissipation. It also provides an electrical conduction path that could result in instrument failure, especially under high-humidity conditions. {caution § Avoid the use of chemical cleaning agents which ‘might damage the plastics used in this instrament. Use @ nonresidue-type cleaner, preferably isopropyl alcohol, denatured ethy! alcohol, or @ solution of 1% ‘mild detergent with 99% water. Before using any ‘other type of cleaner, consult your Tektronix Service Center or representative. 62 Exterior INSPECTION. Inspect the external portions of the Instrument for damage, weer, and missing parts; use Table 6.2 as a guide. Instruments that appear to have been dropped or otherwise abused should be checked thoroughly to verify correct operation and performance. Deficiencies found that could cause personal injury or could lead to further damage to the instrument should be repaired immediately. {Saonen} ee eee See eee CLEANING. Loose dust on the outside of the instru: ment can be removed with a soft cloth or small soft-bristle brush. The brush is particularly useful for dislodging dirt fon and around the controls and connectors. Dirt that remains can be removed with a soft cloth dampened in a mild detergent-and.water solution. Do not use abrasive cloanors. Clean the light filter and the ert face with a soft lint-free cloth dampened with sither denatured alcohol or ‘a mild detergent-and water solution, Interior To gain access to internal portions of the instrument for inspection and cleaning, refer to the “Removal and Replacement Instructions” in the “Corrective Maintenance art of this section. INSPECTION. Inspect the internal portions of the instrument for damage and wear, using Table 6:3 as a guide. Deficiencies found should be repaired immediately. The corrective procedure for most visible defects is obvious; however, particular care must be taken if heatdamaged ‘components are found, Overheating usually indicates other trouble in the instrument; therefore, itis important that the ‘cause of overheating be corrected to prevent recurrence of the damage.Tabe62 Maintenance~2215 Service External Inspection Checklist Item Inspect For Cabinet and Front Panel Cracks, scratches, deformations, and damaged hardware or gaskets, ‘Touch up paint scratches and replace defective parts Front-panel Controls Missing, damaged, or loose knobs, buttons, and controls. Repair or replace missing or defective items. Connectors Broken shells, cracked insulation, and deformed contacts. Dirt in connectors Replace defective parts, Clean or wash out dirt, Carrying Handle Corract operation, Replace defective parts, Accessories Missing items or parts of items, bert pins, Replace damaged or missing items, frayed broken or frayed cables, and damaged cables, and defective parts, connectors. Table 6-3 Internal Inspection Chect ftom Inspect For Repair Action Circuit Boards Loose, broken, or corroded solder connections. | Clean solder corrosion with an eraser and flush Burned circuit boards. Burned, broken, oF with isopropyl alcohol, Resolder defective cracked circuit-run plating connections. Determine cause of burned items and repair. Repair defective circuit runs. Resistors Burned, cracked, broken, or blistered, Solder Connections Capacitors old solder or rosin joints Damaged or leaking cases. Corrodes solder on loads or terminals. Replace defective resistors. Check for cause of ‘burned component and repair as necessary. Resolder joint and clean with isopropyl alcohol Replace defective capacitors, Clean solder connections and flush with isopropyl aleahol, Wiring and Cables Loose plugs or connectors. Burned. broken, or frayed wiring Firmly seat connectors. Repair or replace defective wires or cables. Chassis Dents, deformations, and damagedhardware. ‘Straighten, repair, or replace defective hardware, If any electrical component is replaced, conduct Performance Check of the affected circuit and of other closely rolated circuits (see Section 4). If ropair or replace: ‘ment work is done on any of the power supplies, conduct @ complete Performance Check and, if so indicated, an trument readjustment (see Section 5. } caurion To prevent damage from electrical arcing, ensure that circuit boards and components are dry before applying power to the instrument. CLEANING. To clean the interior, blow off dust with dry, low-pressure air (approximately 9 psi. Remove any remaining dust with a soft brush or aclath dampened with a solution of mild dotergont and water. A cotton-tipped applicator is useful for cleaning in narrow spaces and on cireuit boards, If these methods do not remove all the dust or dirt the instrument may be spray washed using a solution (of BX mild detergent and 95% water as follows: 1, Gain access to the parts to be cleaned (see “Removal and Replacement Instructions 63Maintenance—2215 Service 2. Spray wash diny parts with the detergent-and.wvater solution; then use clean water to thoroughly rinse them, 3. Dry all parts with low-pressure air. SWITCH CONTACTS. The Vertical and Horizontal attenuators in this instrument are circuit-board mounted rotary switches. When cleaning them, care must be exer ised to preserve their high-frequency characteristics ‘Switch maintenance is seldom necessary, but if it is required, use the following cleaning method and observe the stated precaution, } CAUTION § Use only hot deionized or distilled water, 55°C (137°FI, to clean a rotary switch in this instrument. Tap water contains impurities which are left as residuals after evaporation. 1. Spray hot water into the slots at the top of each switch housing while rotating the switch control knob, Spray only for approximately five seconds, using an atomizing spray device. 2. Dry both the switch and the circuit board an which it is mounted, using dry low-pressure air. Bake the switch and the circuit board at 75°C (167°F) for 16 minutes to eliminate all moisture 4. Spray a very small amount (only about a 1/2-second squirt) of @ recommended lubricant, such as No Noise, into the slots at the top of the switch housing. 5. Rotate the switch control knob about 180° and again spray a very small amount of lubricant into each slot. 64 LUBRICATION Most of the potentiometers used in this instrument are permanently sealed and generally do not require periodic lubrication. All switches, both rotary: and. lever-type, are installed with proper iubrication applied where neces sary and will rarely require any additional lubrication. Thorefore, a regular periodic lubrication progran for the instrument is not recommended, SEMICONDUCTOR CHECKS Periodic checks of the transistors and otter semi: conductors in the oscilloscope are not recommended, The best check of semiconductor performance is actual operation in the instrument, PERIODIC READJUSTMENT To ensure accurate measurements, check the perform ance of this instrument after every 2000 hours of eperation, (or if used infrequently, once each year. In addition, replace. ment of components may necessitate readjustment of the affected circuits Complete Performance Check and Adjustment instruc tions are given in Sections 4 and 5, The Performance Check Procedure can also be helpful in localizirg certain trouble in the instrument. In some cases, minor problems may be revealed or corrected by readjustment, If only a partial adjustment is performed, see the interaction chart, Teble 6-1, for possible adjustment interactions with other‘Maintonanco—2218 Service TROUBLESHOOTING INTRODUCTION Preventive maintenance performed on a regular basis should reveal most potential problems before an instrument ‘malfunctions, However, should troubleshooting be required, the following information is provided to facilitate location ‘of @ fault. In addition, the material presented in the “Theory of Operation’ and the “Diagrams” sections of this ‘manual may be helpful while troubleshooting, TROUBLESHOOTING AIDS ‘Schematic Diagrams Complete schematic diagrams ate located on tabbed foldout pages in the “Diagrams section. The portions of circuitry that are mounted on each circuit board are enclosed within heavy black lines. Also within the black lines, near either the top or the bottom edge, are the assembly number and name of the circuit board, Component numbers and electrical values of compo: rents inthis instrument are shown on the schematic diagrams. Refer to the first page of the “Diagrams” section for definitions of the reference designators and symbols Used to identity components. Important voltages and wave. form reference numbers (enclosed in hexagonalshaped boxes) are also shown on each diagram, Waveform illus trations are located adjacent to their respective schematic diagram, and the physical location of each waveform test Point is shown on the appropriate circuit board illustration ircuit Board Illustrations Circuit board illustrations (showing the physical location fof each component) are provided for use in conjunction with each schematic diagram. Esch board illustration can be found on the back side of a foldout page, preceding the schomatic diagrams) to which it relates, If more than one schematic diagram is associated with a particular circuit board, the board illustration is located on a leftthand age preceding the diagram with which the board is frst associated, ‘Also provided in the “Diagrams” section is an illus ‘ration of the bottom side of the Main circuit board, This drawing facilitates troubleshooting by showing the con- nection pads and the location of components that are mounted on the top side of the board. Probing of Main board component signals that are inaccessible from the top side can be achieved without the necessity of dis ‘assembling portions ofthe instrument, Waveform test point locations are also identified on the circuit board illustration by hexegonal-outlined numbers that correspond to the waveform numbers appearing on bboth the schematic diagram and the waveform illustration, Circuit Board Locations An illustration depicting the location of a circuit board within the insteument is shown on the foldout page adjacent to the circuit board illustration, Circuit Board Interconnection Diagram {A circuit board interconnection diagram is also provided in the “Diagrams” section to aid in tracing a signal path or power source between boards. The entire oscilloscope is, illustrated, with plug and jack numbers shown along with associated pin numbers. The oft-board components are also shown, and the schematic diagram numbers on which these components can be found are identified. Power ribution Diagram ‘A Power Distribution diagram is provided to sid in ‘troubleshooting power-supply problems. This diagram shows service jumpers used to remove poner from the various circuit boards. Excessive loading on a power supply by a circuit board can be isolated to the faulty board by disconnecting appropriate service jumpers Grid Coordinate System Each schematic diagram and circuit board illustration has @ grid border along its left and top edges. A table located adjacent to each schematic diagram lists the arid coordinates of each component shown on that schematic. To aid in physically locating @ component on the respective circuit board, this table also lists the circuit-board grid coordinate of each component, Adjacent to each circuit board illustration i¢ an alpha- ‘numeric listing of every component mounted on thet board, A second column in this listing identifies the schematic diagram in which each component can be found, ‘These component-locator tables are especially useful when more than one schematic diagram is associated with a Particular circuit board, 65Maintenance—2215 Service Troubleshooting Charts The troubleshooting charts contained in the “Diagrams” section ate to be used as an aid in locating malfunctioning circuitry. To use the charts, begin with the Troubleshooting Guide, This chart will help identify a particular problem area for further troubleshooting Note that some troubleshootingprocedure boxes on each chart contain numbers along their lower edges. These rumbers identify the applicable schematic diagram (s) to be used whon performing the action specified in the box. Both General and Specific notes may be called out in the troubleshooting-chart boxes. These notes are located on. the inner panels of the foldout pages. Specific Notes contain procedures or additional information to be used in performing the particular troubleshooting step ealled for in ‘that box. General Notes contain information that pertains to the overall troubleshooting procedure, ‘Some malfunctions, especially those involving multiple simultaneous failures, may require more elaborate trouble- shooting approaches with references to circuit descriptions in the “Theory of Operation” section of this manual. Component Color Coding Information regarding color codes and markings of resistors and capacitors is located in the color-coding illustration (Figure 9-1) at the beginning of the “Diagrams” section, RESISTOR COLOR CODE. Resistors used in this instr: ment are carbon-film, composition, or precision metal-film ‘types, They are color coded with the EIA color code: however, some metal-film resistors may have the value printed ‘on the body. The color code is interpreted by starting with the stripe that is nearest to one end of the resistor, Composition resistors have four stripes; these represent two significant figuees, a multiplier, anda tolerance value. Metalfilm resistors have five stripes which represent three significant figures, a multiplier, and a tolerance value CAPACITOR MARKINGS. Capacitance values of common dise capacitors and small electrolytics are marked. fon the side of the capacitor body. White ceramic capacitors are color coded in picofarads, using a modified EIA code. 66 Dipped tantalum capacitors are color coded in micro: farads. The color dot indicates both the positive ead and ‘the voltage rating, Since these capacitors are easily destroyed by reversed or excessive voltage, be careful 0 observe the polarity and voltage rating. DIODE COLOR CODE. The cathode end of each glass- encased diode is indicated by either a stripe, a series of stripes, or a dot, For most silicon or germanium diodes marked with a series of stripes, the color combination of the stripes identifies three digits of the Tektronix Part Number, using the resistor color-code system (e., adiode having either a pink or a blue stripe at the cathode end, then a browngray-green stripe combination, indicates Tektronix Part Number 152.0185:00). The cathode and anode ends of a metal-encased diode can be idertified by ‘the diode symbol marked on its body. Semiconductor Lead Configurations Figure 9:2 in the “Diagrams” section shows the lead configurations for semiconductor devices used in the instrument. These lead configurations and case styles are typical of those available at completion of the design of the instrument, Vendor changes and performance improve- ment changes may result in changes of case styles or lead. configurations. If the device in question does not appear to match the configuration in Figure 9-2, examine the associated circuitry or consult a semiconductor manu: facturer’s data shoot. Multipin Connectors Multipin connector orientation is indicated by two triangles: one on the holder and one on the circuit board, Slot numbers are usually molded into the holder. When 2 connection is made to circuit-board pins, ensure that the triangle on the holder and the triangle on the circuit board are aligned with each other (see Figure 6-1) TROUBLESHOOTING EQUIPMENT Tho equipment listed in Table 4-1, or equivalent equip- ‘ment, may be useful when troubleshooting this instrument. TROUBLESHOOTING TECHNIQUES ‘The following procedure is arranged in an order that enables checking simple trouble possibilities bofore requiring more extensive troubleshooting, The first four checks ensure proper control settings, connections, ‘operation, and adjustment. If the trouble is not located by ‘these checks, the remaining steps will aid in locating the defective component. When the defective component is(0998.11) 2662-50 Figure 61 located, replace it, using the appropriste replacement procedure given under “Corrective Maintenance” in this section. 3 caurion Before using any test equipment to make measure- _ments on staticsensitive, current-sensitive, or voltage- sonsitive components or assemblies, ensure that any voltage or current supplied by the test equipment does not exceed the limits of the component to be tested. 1. Check Control Settings Incorrect control settings can give a false indication of instrument malfunction. If there is any question about the correct function or operation of any control, refer to either the “Operating Instructions" (Section 2) in this ‘manual or to the instrument Operators Manual. 2. Check Associated Equipment Before proceeding, ensure that any equipment used ‘with this instrument is operating correctly. Verify that Input signals are properly connected and that the inter ‘connecting cables are not defective, Check the power-input- source voltages. To avoid electric shock, disconnect the instrument from the powerinput source before performing vissal inspection, ‘Maintenance—2215 Service 3. Visual Check Perform a visual inspection, This check may reveal broken connections or wires, damaged components, semi- conductors not firmly mounted, damaged circuit boards, or other clues WARNING ) Dangerous potentials exist at several points through: ‘out this instrument. If it 's operated with the cabinet removed, do not touch exposed connections or components. 4. Check Instrument Performance and Adjustment Check the performance of either those circuits where trouble appears to oxist or the entire instrument. The apparent trouble may only be the result of misadjustment. Complete performance check and adjustment instructions are given in Sections 4 and 5 of this manual, 5. Isolate Trouble to a Circuit To isolate problems to a particular area, use the trouble symptom to help identify the circuit in which the trouble Js located. Refer to the troubleshooting charts in the “Diagrams” section as an ad in locating a faulty circuit 6. Check Power Supplies 1 is recommended for safery that an isolation trans former be connected between the ac-power source and the autotransformer whenever troubleshooting ‘is done in the Preregulator and the Inverter Power Supply sections. Most autotranstormers are NOT isolation transformers. Check the power supplies whenever trouble symptoms ‘appear in mare than one circuit, The correct output voltage ‘and ripple for each supply should be measured aetween the supply test point and chassis ground (see Diagram 9 and its associated circuit board illustration). When checking power- ‘supply circuitry utilizing common as the re‘erence, use either @ DMM or an oscilloscope and observe the preceding WARNING. If power supply voltages and ripple are within their fisted ranges, the supply can be assumed to be operating correctly. If any are outside their ranges, the supply may be either misadjusted or operating incorrectly. ‘A defective component elsewhere in the insktument can create the appearance of a power-supply problem and may also affect the operation of other circuits 67Maintenanes—2215 Service 7. Check Circuit Board Interconnections After the trouble has been isolated to @ particular circuit, again check for loose or broken connections ‘and heat-damaged components, 8. Check Voltages and Waveforms Often the defective component can be located by checking the appropriate voltage or waveform in the circuit. ‘Typical voltages are listed on the schematic diagrams. Waveforms are shown adjacent to the schematics, and wave: form test points are indicated an both the schematies and Circuit board illustrations by hexagonal outlined numbers. NOTE Voltages and waveforms given on the schematic diagrams are not absolute and may vary slightly between instruments. To establish operating con- ditions similar to those used to obtain these readings, s2e the “Voltage and Waveform Setup conditions in the “Diagrams” section for the preliminary equip- ‘ment setup. Note the recommended test equipment, initial frontpanel control settings, and cable- connection instructions. The control-setting changes (from initial setup) required to obtain the given waveforms and voltages aro located on the waveform: diagram page. WARNING ) To avoid electric shock, always disconnect the instru- ‘ment from the power input source before removing ‘r replacing components 9. Check Individual Components The following procedures describe methods of checking individual components. Two-lead components that are soldered in place are most accurately checked by first disconnecting one end from the circuit board, This isolates the measurement from the effects of surrounding circuitry, Seo Figure 9-1 for value identification or Figure 9:2 for typical semiconductor lead configuration. : 3 S cauTion § When checking semiconductors, observe the stati: sensitivity precautions located at the beginning of this section. TRANSISTORS. A good check of transistor operation is actual performance under operating conditions. A tran sistor can most effectively be checked by substituting a 68 known good component. However, be sure that circuit ‘conditions are not such that a replacement transistor might also be damaged, If substitute transistors are not available, use a dynamic tester. Static-type testers are not recom. ‘mended, since they do not check operation under simulated ‘operating conditions. When troubleshooting transistors in the eireuit with @ voltmeter, measure both the emitter-to-base and emitter to-collector voltages to determine whether they are con: sistent with normal circuit voltages. Voltages across a transistor may vary with the type of device and its circuit function Some of these voltages are predictable. The emitter- to-base voltage for a conducting silicon transistor will normally range from 0.6 to 0.8 V, and the emitter-to- bbaso voltage far @ conducting germanium transistor ranges from 0.2 to 0.4 V. The emitter-to-collector voltage for a saturated transistor is about 0.2 V. Because these values ‘re small, the best way to check them is by connecting a sensitive voltmeter across the junction rather shan com: paring two voltages taken with respect to ground. If the former method is used, both leads of the voltmeter must be isolated from ground, If values less than these are obtained, either the device Is shorted or no current is flowing in the external circuit, If values exceed the emitter-to-base values given, either the junction is reverse biased or the device is defective, Voltages exceeding those given for typical emitter-to-ollestor values could indicate either 2 nonsaturated device operating normally or a defective (open-circuited) transistor. If the dovice is conducting, voltage will be developed across the resistors in series with it; if it is open, no voltage will be developed across the resistors in series with it, unless current is being supplied by a parallel path, ceacrien ee ote ae gee ne ae a foe eae mea ‘A transistor emitter-to-base junction also can be checked for an open ot shorted condition by meaiuring the resistance between terminals with an ohmmeter set to a range having a low internal source current, such es the RX 1K range, The junction resistance should be very high in one direction and very low when the meter leads are reversed.When troubleshooting a field-effect transistor, the voltage across its elements can be checked in the same manner as previously described for other transistors, However, remember that in the normal depletion mode of operation, the gate-tosource junction is reverse biased; in the enhanced mode, the junction is forward biased, INTEGRATED CIRCUITS, An integrated circuit (IC) ccan be checked with a voltmeter, test oscilloscope, oF by direct substitution. A good understanding of circuit operation is essential to troubleshooting a circuit having ‘an IC. Use care when checking voltages and waveforms around the IC so that adjacent leads ate not shorted ‘together. The grabber tip or an IC test clip provides @ ‘convenient means of clipping a test probe to an IC. Veaurion 3 range that has a high internal current. High current Can comoge the ode, Checks on diodes can be teromed in ch the sare manner es on tonstor tmitrto-bse unctons Bo not check tunnel odes rrr taser such the TEKTRONIX 976 Curve Tracer, DIODES, A diode can be checked for either an open or {shorted condition by measuring the resistance between terminals with an ohmmeter set to a range having a low internal source current, such as the RX 1k®2 range. The diode resistance should be very high in one direction and very low when the meter leads are reversed. Silicon diodes should have 0.6 to 0.8 V across their junctions when conducting. Higher readings indicate that they are either revorse biased or defective, depending on polarity Maintenance~2215 Service RESISTORS. Chock resistors with an ohmmeter, Refer to the “Replaceable Electrical Parts” lst for the tolerances of resistors used in this instrument. A resistor normally does not require replacement unless its measured value varies widely from its specified value and tolerance. INDUCTORS. Check for open inductors by checking continuity with an ohmmeter, Shorted or partially shorted inductors can usually be found by checking the waveform response when high-frequency signals are passed through she circuit CAPACITORS. A leaky or shorted capacitor can best be detected by checking resistance with an ohmmeter set ‘to one of the highest ranges. Do not excced the voltage rating of the capacitor. The resistance reading should be high after the capacitor is charged to the output voltage of the ohmmetor. An open capacitor can be detected with | capacitance meter or by checking whether the capacitor passes ae signals, 10. Repair and Adjust the Circuit If any defective parts are located, follow the replace: ment procedures given under "Corrective Maintenance” in this section, After any electrical component has been replaced, the performance for that particular circuit should be checked, 2s well as the performance of other closely related circuits, Since the power supplies affect al circuits, Performance of the entire instrument should be chacked if, ‘work has boen done in any of the power supplies or if the power transformer has been replaced, Readjustment of the affected circuitry may be necessary. Refer to the "Per formance Check Procedure’ and “Adjustment Procedure” (Sections 4 and 5) and to Table 51 (Adjustment Interactions) 69