2 YEAR LIMITED WARRANTY

This product is warranted by CERONIX to be free of defects in material

and workmanship for a period of two years from the date of purchase.

In case of a fault, developed during this time, it is the customer's

responsibility to transport the defective unit to CERONIX or
one of the authorized service centers for repair.
Please attach a note describing the problem.
All parts and labor are free of charge during the warranty period.

CERONIX
12265 Locksley Lane
Auburn, CA. 95602-2055
(530) 888-1044

This warranty does not cover mechanical breakage due to physical abuse.

CERONIX shall not be liable for any consequential damages, including

without limitation damages resulting from loss of use.
Some states do not allow limitation of incidental or consequential
damages, so the limitation or exclusion may not apply to you.

This warranty gives you specific rights and you may also have
other rights which vary from state to state.

®
Recognized under the Component Program
of Underwriters Laboratories Inc. and
® the Canadian Standards Association.

COPYRIGHT © 1988, 1990, 1998

CERONIX

All rights reserved.

The information contained in this manual

is subject to change without prior notice.
ABOUT THIS MANUAL

This manual is specifically written to aid the service technician, repairing

CERONIX Models 1492 and 2092 color monitors.

There are three main sections:

1. General Description.
2. Circuit Description.
3. Solutions to Problems.

INTRO- Block BLOCK Schematic Circuit Problem Appendix

DUCTION Diagram Diagram Description Solving A
Description Tools & Video
Examples Interface
programs

To understand how the Monitor works, it is best to know what each

circuit does and how each circuit relates to the other circuits.
The Block Diagram is presented in a simplified view and a comprehensive
view to accomplish the goal of understanding the whole unit.
Once the general picture is clear, the complexity of each circuit will be easier
to understand.

The Circuit Description is also written in two views, a simplified view

and a detailed view to help give the reader a clear understanding of
what each component does. This understanding is most helpful for the more
complex problems or multiple problems that sometimes occur.

The Trouble Finder section is made up of an index, which lists

symptoms of problems, and a list of possible solutions. Part of this section
also deals with setting up conditions which make it easier to trouble shoot
specific circuits such as the power supply.

1
 TABLE OF CONTENTS
About This Manual. 1
CERONIX Models 1492 and 2092 Electrical Specification. 3&4
Drive Signals to the Monitor Input voltage and waveforms, work sheet. 5

1492 and 2092 Simplified Block Diagram. 6

Video Section Description. - - - - - - - Blocks A-D 7
Auto Bias and Socket Board. - - - - - - Blocks E-G 8 Block
Blanking, Sync, & Vertical. - - - - - - - Blocks H-L 9 Diagram
Horizontal Deflection & Remote. - - - Blocks M-Q 10
Description
Horizontal Size & Power Supply. - - - Blocks R-U 11
Power Supply Continued. - - - - - - - - Blocks V-Y 12
1492 and 2092 Monitor BLOCK DIAGRAM. 13

1492 and 2092 Monitor SCHEMATIC 14 & 15

Video Interface Circuit Description. 16 & 17 Video

Video Interface Schematic. 18
Socket Board
Video Amplifier Circuit, Function, Description. 19
Video Amplifier Circuit Description. 19 & 20 Blanking
Socket Board, Degaussing Circuit, and Legend Description. 21 Master Gain
Blanking and Master Gain Circuit, Function, Description. 22 Circuit &
Blanking and Master Gain Circuit Description. 23 Function
Blanking and Master Gain Schematic. 24 Description

Replacement PARTS LIST. 25 & 28

1492 and 2092 Main Board ASSEMBLY DRAWING. 29 & 30

Block Diagram Review. 31

Auto Bias and Auto Bright Circuit, Function, Description. 32 Auto Bias
Auto Bias and Auto Bright Circuit Description. 33 Auto Bright
Auto Bias and Auto Bright Schematic. 34
Vertical and Horizontal Sync Circuit Description. 35 Sync
Vertical Deflection Circuit, Function, Description. 36 Vertical
Vertical Deflection Circuit Description. 37 & 38
Horizontal Deflection Circuit Description. 39 & 40 Horizontal
Horizontal Raster Width Control Circuit Description. 41 Power Supply
Horizontal Raster Width and Position Control Schematic. 42
Simplified Power Supply Circuit, Function, Description. 43 Circuit &
Simplified Power Supply Circuit Description. 44 Function
Switch Mode Power Supply Circuit Description. 45 Description
Switch Mode Power Supply Schematic. 46

Equipment setup for repairing the Model 1492 Monitor. 47

Problem Solving Tools. 48
Appendix A --- Setup and Convergence Procedure. 49
Appendix B --- Video Interface Programs. 50 to 55
Appendix C --- Resistor Array Layout for; B, C, G, H, I, & J. 57 & 58
2
 CERONIX MODELS 1492 and 2092 Electrical Specification

INPUTS
1492 & 2092
1. Standard Video Configurations, available, are:
Min. Typ. Max
A. Positive Analog
Video
Source Video
.6mA To Amp.
Source
only { Black level
Saturated color
0V
3.1V
0V
3.2V
.05V
3.3V
Source
D-A 301ý Gnd 301 ý
Monitor and
Monitor { Black level
Saturated color
.06V
1.61V
.09V
1.69V
.15V
1.75V

B. Negative Analog
Video To Amp.
Source Red & Green Black level 5.4V 5.6V 5.8V
Video 905 ý V Blk.+.7 V
D-A Blue Black level 4.85V 5.05V 5.25V
Gnd R IN Monitor
Saturated color .7V .9V 1.1V

C. 4 Line TTL
R,G,B Black level 0V .2V .5V
Video To Amp. +12V
Video Color on
Source VB 2.7V 3.5V 6.0V
* Intensity
BIAS Low intensity 0V .2V .4V
Gnd Monitor
Full intensity 4.5V 4.6V 4.8V
* No pullup resistor on intensity line.
Note: RS170 and other voltage combinations optional for analog video.

2. The Sync signals may be of either polarity and separate or composite.

Sync Hs 1.8K
High input voltage 2.2V 3.5V 20V
Source .15V
Vs 1.8K Low input voltage -2.7V .30V .80V
Gnd 220 ý, 2 PL Horizontal sync pulse 1.5uS 4.5uS 31uS
Monitor
Vertical sync pulse 120uS .5mS 1.5mS
For composite sync, vertical and horizontal
sync lines are connected together. Horizontal frequency 15.3KHz 15.6KHz 15.9KHz
60Hz 65Hz
Vertical frequency
45Hz 50Hz

3. The Power to the monitor is to be

supplied by a secondary winding Model 1492 Model 2092
of an isolation transformer. Min. Typ. Max. Min. Typ. Max.
115VAC 50Hz or 60Hz 85VAC 115VAC 145VAC 90VAC 115VAC 145VAC
230VAC 50HZ or 60Hz 170VAC 230VAC 290VAC 180VAC 230VAC 290VAC
Power 32W 44W 60W 30W 50W 67W

3
4. The remote Controls are located on Model 1492 Model 2092
a separate PCB for easy access.
Min. Max. Min. Max.
H SIZE--------------Horizontal raster size 9.9" 11.4" 14.8" 16.3"
V SIZE---------------Vertical raster size 6.3" 10.3" 10.0" 14.0"
V RAS. POS.-----Vertical raster position 0" .44" 0" .60"
H POS-------Horizontal picture position* .9" Right 2" Left 1.2 right 2.8" left
M GAIN---------------------Master gain Dark Light Dark Light
Screen Screen Screen Screen

The board Controls are located on the main PCB, and are:
Focus on the flyback transformer and an optional Horizontal hold control.
* For start of horizontal sync 1.7uS after end of picture.
5. Picture Model 1492 Model 2092
Min. Typ Max. Min. Typ Max.
Video response is measured at the Rise time35nS .
44nS 49nS .
37nS 46nS 52nS
tube socket, using low capacitance Fall time 32nS 42nS 47nS
coupling. The input signal should
35nS 44nS 50nS
be fully damped and faster than Overshoot 0% 0% 2% 0% 0% 2%
the expected response. Band width DC to 8MHz DC to 8MHz
Horizontal blank time 12.4uS 12.9uS 13.4uS 12.4uS 12.9uS 13.4uS
Vertical blank time 20H 1.28mS 20H 20H 1.28mS 20H
Horizontal linearity 1% 2% 1% 2%
Vertical linearity 1% 2% 1% 2%
Pincushion 1% 2% 1% 2%

6. Picture tube Model 1492 Model 2092

Inch mm Inch mm
Useful diagonal 13 328 20 508
Useful horizontal 10.83 275 16 406.6
Useful vertical 8.13 206.5 12 304.8
Useful area 86 558 192 1,239
Spacing between dot/line trios .015 .39 .029 .74
Horizontal resolution 680 Pixels 550 Pixels
Vertical resolution 240 Pixels 240 Pixels
Interlaced 480 Pixels 480 Pixels
Deflection angle 90° 90°
Light transmission at center of glass Approximately 46% Approximately 46%
CRT also features: Enhanced contrast, Internal magnetic shield, and
X-Ray output Less than .3mR/hour.
7. Environmental Operating temperature 0° C 70° C 0° C 70° C
Storage temperature -20° C 85° C -20° C 85° C
Operating humidity 20% 80% 20% 80%
Storage humidity 10% 95% 10% 95%

4
The "Drive Signals To The Monitor Input" form is included here for those people who have
problems interfacing their drive electronics with the Ceronix Monitor.

DRIVE SIGNALS to the MONITOR INPUT

voltage and waveforms, work sheet.
Company name:
CERONIX Date:
12265 Locksley Lane Drive signal source
Auburn, CA, USA 95602-2055 Model number:

VIDEO: For the following measurements use an oscilloscope.

RED GREEN BLUE
With no load the black level voltage is:
With no load the saturated color voltage is:
With 301ý load
or other
To GND, or to
voltage
ý load.

V.
} the black level voltage is:
the saturated color voltage is:

If available, sketch the video drive circuit on the back of a copy of this form.

Horizontal or composite sync:

Horizontal frequency: Hz "High" voltage: V
Horizontal sync pulse time: uS "Low" voltage: V

Compare your sync to

this table and check
the best fit.

For composite sync.

Sketch if different.

Vertical sync:
Vertical frequency: Hz "High" voltage: V
Vertical sync pulse time: uS "Low" voltage: V

Check correct polarity.

Complete form and send to: CERONIX, 12265 Locksley Lane

If there are any questions, call (530) 888-1044. Auburn, CA. 95602-2055 5
 1492 and 2092 Simplified Block Diagram

VIDEO VIDEO VIDEO

Output Interface Amps. CRT

GAME
Blanking AUTO BIAS

SYNC
Output Vertical Deflection

FBT
Horizontal Deflection

Remote Horizontal Size

Controls Control
Isolated
Power POWER SUPPLY

This block diagram gives a broad view of the circuit organization of

the 1492 and 2092 monitors. The blocks with the bold outline represent
circuits that are quite different than most other monitors.

The auto bias circuit is designed to actively compensate for picture

tube and circuit drift which normally cause the color balance to become
unbalanced and also brightness variation. This circuit eliminates the need
for the color setup procedure.

The horizontal size control circuit permits the horizontal size to be

adjusted from a remote control board instead of a coil on the main board.
It is also used to compensate for pincushion distortion and acts as an
anti-blooming circuit by correcting for horizontal size variations which
are caused by the additional load on the flyback transformer under high beam
current conditions.

The 1492 and 2092 power supplies differ from most other monitors
because of their high efficiency switching mode power supply. It is not
difficult to troubleshoot if the techniques presented in this manual are
clearly understood. Careful reading of all the information presented in this
manual will make trouble shooting of the CERONIX monitor no more difficult
than any other monitor and maybe even easier.

6
 Refer to the block diagram on page 13 (foldout) when reading this description.

The Video Interface is designed around a custom IC and will accept positive
or negative analog video signals and also 4 line TTL. This IC also has a
built in multiplier circuit for the master gain control and blanking.
Resistors are used to protect the IC and to set the gain. The programmed gain
is dependent on the input signal amplitude except on TTL. Solder jumpers are
used to program the Video Interface for the type of input signal to be received.
The output of the IC drives the video amplifiers. This drive is a current where
0 mA is black and 4.5 mA is a saturated color.

B
The Video Amplifiers are of the push pull type. They are built partly on
thick films and partly on the PCB. Spreading out the amplifier reduces the
component heat and improves the life of the unit. The bandwidth is 8 MHz
with 60Vp-p output. The rise and fall times are .04uS.

C
The Beam Current Feedback circuit directs most of the beam current of each
amplifier to the beam current buffer. The only time this current is measured by
the auto bias circuit is during the time of the three faint lines at the top of the
screen and three lines thereafter. The auto bias circuit is designed to adjust the
video amplifier bias voltage such that the beam current of each of the three guns is
set (programmed), at this time.

D
The Beam Current Buffer converts the, high impedance low current, beam
current signal into a low impedance voltage. This voltage is applied to the
auto bias IC through a 200 ohm resistor. After the three lines of beam
current are measured, the program pulse from the auto bias IC, produces a
voltage drop across this 200 ohm resistor that equals the amplitude of the
beam current voltage.

7
 E

The Auto Bias IC is a combination of digital and analog circuitry.

The digital part is a counter and control logic which steps the analog
circuits through a sequence of sample and hold conditions.
The analog part uses a transconductance amplifier to control the voltage on
a 10uF capacitor (one per gun). This voltage is buffered and sent to the
video amplifiers as the bias voltage. In monitors without auto bias, this
voltage has to be set manually using a setup procedure to set the color
balance. With the auto bias, the color balance is set during the end of each
vertical blanking time.

The control sequence is:

1. Grid pulse on G1 causes cathode current (3 lines top of screen)
which is transmitted by the beam current feedback to the beam
current buffer where it is converted to a voltage and applied to
the auto bias input pin.
2. Auto bias IC outputs a reference voltage at its input pin which
sets the voltage across the coupling capacitor. This coupling
capacitor voltage is directly dependent on beam current.
3. After the grid pulse is over, the program pulse matches the

voltage from the beam current buffer. If the voltage from the
beam current buffer, during the grid pulse, is the same as the
voltage from the program pulse, the bias is correct and no bias

F
The aging of the picture tube (CRT) not only affects the balance of the
cathode cutoff voltage, which is corrected by the auto bias circuit, but
it also affects the gain of the CRT. The Auto Bright circuit actively
corrects for CRT gain changes by sensing any common bias change from
the auto bias circuit and adjusts the screen voltage to hold the average
bias voltage constant. The lower adjustment on the flyback
transformer is used to set the auto bright voltage to the center of
its range. This sets up a second control feedback loop to eliminate
picture variation due to the aging of the picture tube.

The CRT is a 90° deflection type color picture tube with a 25KV EHT
and has integral implosion protection.

8
 H
Blanking is accomplished by setting the gain of the interface IC to zero during
blank time. The Horizontal Blanking pulse is generated by amplifying the flyback
pulse. The Vertical Blanking pulse is started by the vertical oscillator and ended
by the counter in the auto bias IC via the "bias out" pulse. The Master Gain control,
located on the remote PCB, sets the gain of the video signal when blanking is not
active. The Beam Current Limiter circuit, which is designed to keep the FBT from
overloading, will reduce the video gain if the average beam current exceeds .75mA.

I
The Sync Interface can be made to accept separate or composite sync. Two
comparators are used to receive sync, one for vertical sync and the other for
horizontal sync. Resistor dividers are used to protect the comparator IC from
over voltage damage.
J
The Vertical Control circuit consists of:

1. Vertical sync circuit.

2. Vertical oscillator.
3. Linear ramp generator.
4. Output control and bias circuits for controlling the power driver.
The active components that make up these circuits, except for part of the bias circuit,
are located in the deflection control IC (LA7851). The vertical sync circuit is capable
of accepting either positive or negative going sync pulses without adjustment.
The vertical oscillator in the LA7851 is set at 45 Hz and will sync up to 65 Hz
without adjustment. The deflection yoke is driven with a linear current ramp which
produces evenly spaced horizontal lines on the raster. This linear ramp is generated
by supplying a 1uF capacitor with a constant current. The vertical output voltage is
held within range (biased) by a timer which partly discharges the 1uF ramp capacitor
at the start of vertical retrace. The duration of the timer is controlled by the vertical
output voltage and the vertical auto bias circuit.

K
The Vertical Auto Bias circuit greatly increases the range of the bias circuit built
into the LA7851. It is made up of a negative peak detector and an amplifier which
outputs current to the normal bias circuit, but with a much lower frequency response.
This then eliminates the need for adjustments during production and permits the use
of 50Hz and 60Hz vertical sync with only a size adjustment on the remote control board.

L
The Vertical Output circuit (LA7830) is a power driver which drives the vertical
deflection yoke. It also has a special pump up circuit which doubles the output
voltage during vertical retrace. This voltage doubler also doubles the efficiency of
the circuit since the high retrace voltage is not present across the power driver
during the trace time.
9
 M
The Horizontal Control incorporates a variable sync delay and a phase
locked loop to generate the horizontal timing. The H POS. adjustment on the
remote control board sets the sync delay time which controls the picture position.
The phase locked loop uses the flyback pulse to generate a sawtooth wave
which is gated with the delayed sync pulse to control the horizontal oscillator.

N
The Horizontal Driver supplies the high base current necessary to drive the
horizontal output transistor which has a beta as low as three.
It also protects the horizontal output transistor since it is a transformer and
cannot keep the base turned on for longer than its inductive time constant.

O
The Horizontal Output transistor is mounted to the rear frame which acts as
a heat sink. The collector conducts 1,000 volt flyback pulses which should
not be measured unless the equipment is specifically designed to withstand
this type of stress. A linear ramp current is produced in the horizontal
yoke by the conduction of the horizontal output transistor (trace time).
A fast current reversal (retrace time) is achieved by the high voltage pulse
that follows the turn off of the horizontal output transistor. This pulse is due
to the inductive action of the yoke and flyback transformer.

P
The main function of the Flyback Transformer (FBT) is to generate a
25,000 volt (EHT) potential for the anode of the picture tube. This voltage
times the beam current is the power that lights up the phosphor on the face
of the picture tube. At .75mA beam current the FBT is producing almost 19
watts of high voltage power. The FBT also sources the focus voltage and the
filament power. The FBT has a built in high voltage load resistor which
stabilizes the EHT, for the low beam current condition. This resistor also
discharges the EHT, when the monitor is turned off, which improves the
safety of handling the monitor.

Q
The Remote Control PCB houses the:

CONTROL DESCRIPTION CIRCUIT

1. H SIZE ----------- Horizontal raster size --------- Diode modulator
2. V SIZE ----------- Vertical raster size ------------- Vertical drive
3. V RAS. POS. --- Vertical raster position ------- DC current to V. yoke
4. H POS ------------ Horizontal picture position -- H. sync delay
5. M GAIN ---------- Master gain ---------------------- Video interface

10
 R
The Horizontal Size Control circuit has four inputs:
# SIGNAL FUNCTION
1. Horizontal size ---------------------- Horizontal size control
2. Beam current ----------------------- Blooming control
3. Vertical linear ramp ---------------- (#4)-(#3)=Vertical parabolic
4. Vertical parabolic + V. linear ramp (Pincushion)

The horizontal size control circuit sums the four signals at one node to
produce the diode modulator control voltage.

S
The Diode Modulator is a series element of the horizontal tuned circuit.
It forms a node between GND and the normal yoke return circuit.
If this node is shorted to GND, maximum horizontal size is present.
A diode is used to control the starting time of the retrace pulse at this node.
The reverse conduction time is dependent on the forward current because the
current waveform at this node has to exceed the forward current in the diode.
A diode, placed in series with the yoke, is then used to control the retrace
pulse amplitude across the yoke. The horizontal size, therefore, is controlled by
controlling the current to this diode via the horizontal size control circuit.

T
A Voltage Doubler is used in the power supply for two reasons:

1. To improve the efficiency of the power supply.

2. To permit 120 volt and 220 volt operation. For the 220 volt
operation the voltage doubler is replaced with a bridge rectifier.

U
The Switching Regulator is synchronized to the horizontal pulse and drives
a power MOSFET. Unlike most regulators that have a common GND, this
power supply has a common V+ and current is supplied from V- to GND.
The MOSFET is connected to V- and signal ground (GND) through a
transformer which is used as an inductor for series switchmode regulation.
An operational amplifier, voltage reference, comparator, and oscillator
in the power supply controller IC are used to accomplished regulation by
means of pulse width modulation.

11
 The transformer has two taps on the main winding which are used to
generate the +16 volt and +24 volt supplies. It also has a secondary which is
referenced to V- and supplies the power supply. Since the power supply is
generating its own power, a special start up circuit is built into the power
supply controller IC that delays start up until its supply capacitor is
charged up enough to furnish the current to start the power supply.
This capacitor is charged with current through a high value resistor
from the raw dc supply. This is why the power supply chirps when
an overload or underload occurs.

V
The Load consists of the video amplifiers and the horizontal flyback circuit.
The power supply will not operate without the load since the voltage that
sustains the power supply comes from a secondary in the power transformer
and depends on some primary current to generate secondary current.

W & X

A separate +12V regulator for the video and the deflection circuits are used in this
monitor to minimize raster and video interactions. This also simplifies PCB layout,
since the video GND loops are separate from the deflection GND loops.

The Over Voltage Protect circuit is built into the power supply and monitors the
flyback transformer peak pulse voltage. This circuit will turn off the power
supply and hold it off if the EHT exceeds its rated value. This circuit not only
provides assurance that the X-ray specifications are met but also protects the
monitor from catastrophic failure due to a minor component failure.

12
 1492 & 2092 Monitor Block Diagram

GAME
3 VIDEO 3
VIDEO 3
Beam
VIDEO 3
Interface AMPS. Current
CRT
A Bias B Feedback
C G
3
SYNC BLANKING 3 Auto V DY
F.B.P. Bright H DY
V retrace F 3
Beam limit 3
M. gain D
H AUTO BIAS Beam current
buffer
SYNC IC
Interface I Program pulse
H. blank
V. blank Grid pulse
2
E

Vs VERTICAL VERTICAL
CONTROL OUTPUT
I. V. Feedback High Efficiency
J L

VERTICAL
AUTO BIAS
K
EHT

HORIZONTAL H. H. FBT
CONTROL Driver Output
Hs Sync delay N O P
H. Pos. M
V. Size & PINCUSHION
V. Ras. Pos. 2

REMOTE HORIZONTAL DIODE

CONTROLS Size Control Modulator
(PCB) Q R S
Beam Current

+127V

ISOLATION VOLTAGE LOAD (VIDEO & DEFLECTION)

Transformer DOUBLER V
Raw DC
(IN GAME) 320V +12V
T SWITCHING +16V Video
Regulator Supply
REGULATOR +27V
V- -200V W
Sync U
+12V Deflection
Zener Supply
OVER X
VOLTAGE
PROTECT
Y
13
 VIDEO INTERFACE CIRCUIT DESCRIPTION (+ & - Analog)
The video interface circuit is a general purpose RGB type input circuit. This circuit
connects the external video signal to the video amplifiers. It can accept positive going
analog, negative going analog, and 4 line TTL. The particular mode of operation is
selected by placing solder bridges on the foil side of the PCB. The solder bridge patterns
are given in appendix A. Simplified video interface circuit:
Black Level (5.6V)
1. NEGATIVE GOING ANALOG MODE.
+12V RED channel shown 16
Saturated Color (1V)
VIDEO
AMPS
7.5V BIAS LINE
2.2V
R,G,&B 20 200ý 3.6K MG 12 MASTER
VIDEO
6.3V
GAIN&
INPUTS 301ý 604ý 2 C5346 Connections Installed BLANKING
36
21 18 ALWAYS NORMALLY
3 -Analog Black Level (-A BL) Q&Y S&X
62K
16 R

In the negative analog mode, the video signal has a black level which is the -A BL voltage.
This voltage is normally 5.6V and may be set to 5.1V by adding solder connection .R
The saturated color is the lowest input voltage (.9V-1.1V). To prevent input line ringing
from exceeding the saturated color voltage limit, a clamp diode has been added.
20
The current amplitude to the video amplifiers is defined by resistors &21 and
18 the
master gain voltage.

Saturated Color (1.6V or 3.2V)

2. POSITIVE GOING ANALOG MODE.
+12V RED channel shown 16
Black Level (.27V) 7.5V BIAS LINE VIDEO
AMPS
15.8K 11
+ANALOG ENABLE
33
R,G,&B 3.6K MASTER
200ý MG 12
VIDEO 301ý GAIN &
INPUTS 21 2 C5346 Connection Installed BLANKING
ALWAYS NORMALLY
+12V 36
D Y D,E,F,G,H,I,
A 12.1K J,K,L,P, & T
23
3
75ý 301ý 340ý J
05 04 24 340ý

38 M
In the positive analog mode, a bias current flows to the input which is set by resistor 33
at the +Analog Enable input. This current produces a voltage, across the parallel resistance
of the (game and 04 ) plus resistor 21 , at the IC pin 2. Without this bias current the black
level input voltage to the C5346 would be 0V and resistor 23would not be needed.
With a bias resistor of 15.8K, the bias current is .6mA. If the external source resistance is
300 ohms, the black level voltage at pin 2 is .27V. A black level voltage of .3V is set by
resistor divider 23 , 24 to compensate for the bias current voltage drop.
The input termination resistor 04reduces video line ringing and sets a dark
screen when the video input connector is disconnected. The saturated
color is the highest input voltage. There are two standard, saturated color,
voltages available: 1.6V J connected and 3.2V M connected. 16
 VIDEO INTERFACE CIRCUIT DESCRIPTION (TTL)
3. 4 LINE TTL MODE.
+12V RED channel shown 16
7.5V BIAS LINE VIDEO
AMPS
15.8K 11 +ANALOG EN. &TTL
33
R,G,&B +12V 200ý 3.6K MG 12 MASTER
VIDEO 905 ý GAIN &
INPUTS 18 21 2.7V BLANKING
2 Connections Installed

1K (Optional) C5346 ALWAYS NORMALLY

36 None A, B, C,
04 GND P, & T
+12V
INTENSITY 5
3.92K 3.92K
INPUT
03 1.87K 13

15

In the 4 line TTL mode the red, green, and blue video lines will pass color when high.
The intensity of the color is set by the fourth TTL line. Saturated color is displayed when
the intensity line is high or open, and when it is low, the displayed color is half intensity.
Although the R, G, and B lines are logic lines, the intensity line is an analog line.
To insure full saturated color, the TTL driver to the intensity line should have no other loads.
The, 1K to GND, input resistor on the color lines may be installed to keep the screen dark when
no video input cable is connected. The logic 0 voltage at the input is 0 to .4V @ .6mA.
The logic 1 voltage at the input is 2.7V to 5.5V @ -2.1mA with the 1K pulldown and .6mA without.

Refer to the video interface schematic to the right for the following component description.
Both the blanking and the gain control is accomplished by the Master Gain line to the video
interface IC (C5346 pin 12). Resistors 054, 055, 056, 057, & 094 provide five
programmable voltages for setting the max. MG voltage. The video gain is also affected by
each of the input modes. Resistors 021 , 018 , 043 , 044 , 011 , and 014 set the video
gain for the -Analog mode and provide protection to the video interface IC inputs in the
+Analog and TTL modes. Resistors 014 and 030 modify the blue video response in the
Analog mode. The video gain, for the +Analog mode is set by resistors ,
023 024, ,
038
034 , 037 , 035 , 008 , 007 , and 031 . The TTL video gain is set by resistors 003, 013,
and 015 . In the +Analog mode, G , H , AND I are bridged to reduce the offset voltage
caused by the bias current. Also, input termination resistors ,
004 ,026
and are used
001
to improve input line matching. In the TTL mode resistors ,005 ,027 and may be 1K &
002
programmed in. A clamp circuit is used in the -Analog mode to reduce the effect of line ringing.
Resistors 050 and 051 provide a reference voltage which is buffered by PNP transistor ,
053
load resistor 052 , capacitor 025 , and applied to diodes 020, 042, and 012to perform
this clamping function. P is bridged to reference the clamp to GND for the +Analog and TTL
modes. Resistor 016 is used to set the -Analog black level lower than 5.6 volts.
If the -Analog black level is set below 4.9 volts, both resistors &
016 are used to
017
override the chip resistor tolerance. The black level for the blue channel may be increased
for all modes by connecting resistor 030. The C5346 036 has, built in, separate circuits
for each of the three input modes. These modes are selected by bridge points Q & Y .

17
 VIDEO INTERFACE SCHEMATIC

P.S. Master Gain line (MG)

To
Video
S T U 4.2-8.2VDC
Amps. 1.5K 5-10 17mS
909ý 200 ý 412 ý
040
054 056 057
1.62K 2.7K
Y
.1uF 055 094 +12V
GND

032 6.8K 15.8K 62K * 3.92K 3.92K

030 033 016 017 013 003
1.87K
X Q R
015
16 13 9 6 11 10 3 5 12
Ro G o B o A
+ EN +12V - A BL TTL M GAIN
BBL Controls C5346 036
4
GND
R IN RR GIN GR B IN BR
2 1 14 15 7 8
340 ý 340 ý 340 ý
038 035 031

J M K N L O

12.1K 340 ý 12.1K 340 ý 12.1K 340 ý

023 024 034 037 008 007

604ý 604ý 464ý

018 044 014 2.7K
052 +12V
G H I
.1uF .1uF
060
1N4148 1N4148 1N4148 GND
025
020 042 012
4.42K
051

022 041 010 PN2907

301ý 301ý 301ý P
021 043 011
D 301ý E 301ý F 301ý 053

004 026 001 FG 1.00K

A B C 050
75 ý 75 ý 75 ý
FRAME
005 027 002 GND
GND

HORIZONTAL
SYNC
R G B
VC RED VC GREEN VC BLUE VC 4 TH LINE
4 INPUT 5 INPUT 6 INPUT 0 TTL INPUT
18
 VIDEO AMPLIFIER CIRCUIT, FUNCTION, DESCRIPTION
The video amplifier, is a high speed push pull amplifier, which can swing as much as 92 volts.
The maximum dynamic output swing is limited to 60 volts. The rest of the output voltage range
is reserved for bias adjustment. +127V

SIMPLIFIED VIDEO AMPLIFIER CIRCUIT: 270ý 66ý

B14 2SA1370 B15
+12V
40.2K 87B
VIDEO 392ý 1.65K
INTERFACE B5 B11 B17 .015uF
1 + 68K
82B 2SC3467
B1 83B
606ý 7
NE592
B6
14
27ý
790ý 836ý 5.62K B3
C5346 B9 B10
B12 From Auto Bias
control output +7.9V line

The video amplifier's output voltage, With no input signal, is the black level
which is the picture tube cut off voltage. This voltage is set for each of the three video
amplifiers by the auto bias circuit. This black level voltage has a range of 80V to 112V.
The voltage swing at the output is 60 volts for a 4.3 mA current signal from the C5346.
For this same 4.3 mA current signal the voltage swing at the video amp. input is 1.32 volts and the
-input voltage swing at the NE592 is .75 volts. The reason for using the voltage matching resistor
B6 is that the C5346 minimum output voltage is 7.7 volts, and the bias voltage at the NE592
input is 5.3 volts.
VIDEO AMPLIFIER CIRCUIT DESCRIPTION
The control circuit for the video amplifier is located on the B PRA (B precision resistor array).
The B PRA includes all the Bxx resistors and the NE592. All of the parts labeled Rxx
xxR,
xxG , and xxB
xxB , are components located on the circuit board, which are part of the red,
green, and blue video amplifiers.

The video amplifier's stability and precise response to the input signal comes from a
combination of the geometric layout of the B PRA and the high frequency response of the NE592.
The NE592 stabilization capacitor B00B00is an integral part of the B PRA conductor layout.
Resistor B4 B 4 is used to boost the NE592 drive current to the PNP transistor 87B .
The NE592 bias circuit, at the input side, consists of B 5 B5, B6 B6
, and B 9 B9
.
The negative feedback bias resistors are, B11 B11, B10
B10, and B 12
B12 with B 17
B17as the
output feedback resistor. Resistors B19 B19and B20 B20are connected to solder pads which,
when bridged, permit the 1492 B PRA to be used on the models 1490 and 1491 monitors.

The NE592 gain is set by resistor B8 . The drive signal from the NE592, pin 7,
B22
is coupled to the base of the NPN transistor 83Bthrough an impedance matching resistor B2 .B2
This drive is also coupled to the base of the PNP transistor 87B87Bvia a coupling capacitor 82B 82B
.
The NE592 output voltage range is 6V to 10V, which is the reason for the 7.9 volt NPN bias line.
The 7.9 volt bias line is generated by buffering a voltage divider, formed by resistors 97 097
and 100
100 , with a PNP darlington transistor 98 098. A capacitor 9 5 095is connected to
shunt the high current spikes to GND. This line is common to all three video amplifiers.

The AC current gain is set by resistor B3 B3for the NPN output transistor and by B13 B13
for the PNP output transistor which is AC coupled via a capacitor 84B 84B . On a positive
output transition of the video amplifier, the current of the PNP transistor can go
as high as 32mA and on a negative transition the current drops to 0mA 19
 VIDEO AMPLIFIER SCHEMATIC
6 7 8.9-9.8VDC 3 13
1V 4uS
8
Blue Video Amplifier 1.8-2.3VDC
WITH GRID 270ý
+12V 124-126VDC
+127V
392 ý 1.65K 270ý 66 ý B18
B5 B11 40.2K B14 B15
2SA
20 16 1N4148 1370 18
B17 .1uF
8 539 ý 86B 17 87B 15 84B
B20 68K 1 19 32 ý
1 10 B1 .015uF B13
5 510 ý
3 82B 14
B16 80-112VDC
SOT 7 20
Dark screen
606ý 1000pF
B6
1.27K NE592
B8 180ý
12 B22 510 ý 88B 1.5-2.4V
8 B2 2SC
14 85B across
3467 FDH400 85B
3.78K 5
4
.1uF 83B 2.2K
8.0-9.2VDC 90B
B19 1-2V 4uS 2SA 92B
3.3pF 096 2
27 ý PART OF
1370
AUTO BIAS
WITH GRID B3
B00 5.62K 11 2.2K

B12 91B 93B

790 ý 836 ý 1.2K 3.32K
B10 B4 B7 BIAS CONTROL LINE
B9
GND
3 7.4-8.4VDC
81B
+12V +12V +12V

VIDEO INTERFACE 1.21K

VERTICAL and MPS A64
100
HORIZONTAL
MG BLANKING, D
098
Master Gain, & 1.62K .1uF
Beam limiter 097 095
GND GND
R G B
VIDEO SOURCE (external)

For low output distortion, the PNP transistor is biased with a 6 mA current. The NPN
transistor and resistor B 17B17conduct the PNP bias current to GND. Diode 86B 86B balances the
PNP base to emitter voltage. Resistors B1 and B14 set the voltage across B 15B15which
define the video amplifier output stage bias current. A quick way to check this current, is to
measure the voltage drop across the 510 ohm 85B. The permissible voltage range is
listed on the schematic as 1.5-2.4V. The PNP and NPN collector resistors and
B16 85B
help stabilize the amplifier and provide some arc protection. Resistor B 18 B18 is used to decouple
the video amplifiers from the +127V line. Capacitor is used to decouple the +12 volt line
096
close to the video amplifiers. If this capacitor or the 7.9V line capacitor is open, the
095
video may be unstable and distorted. Resistor B7 B7 is the auto bias output load resistor.

If there is a problem with the video, first check the output waveform of the video amplifier,
with the oscilloscope, if ok the problem is not in the video section. If not ok, check the input
waveform at B PRA pin 8, if not ok there, check the video interface, If ok at the video amplifier
input, refer to this section to help with analyzing the video amplifier problems.
20
 SOCKET BOARD , DEGAUSSING CIRCUIT, AND LEGEND DESCRIPTION
TC 432
10 Socket Board
8 PCB 428
TC FDH400 1K 1/2W RED
6
407 406 10
FDH400 8
1K 1/2W GREEN
411 6
408

BLUE 11
FDH400 1K 1/2W

410 404 12
9 5 7 1
* .1uF 250V 470ý 431
1/2W
.68ý 1K
TC 412 414 405 1/2W EHT
10K 1/2W 403 1K 1/2W
3 GRID PULSE 2092 413
422
425 0ý
1K 1/2W EHT
405
TC 2SC3675 100K 1/2W 418 FOCUS
4 100K 330pF 2,200pF SCREEN
417 415
416 47ý 47ý 423 421
FBT
200K 424 402 FIL. TC1 FIL.
420 GND
TC2 FIL.

The primary function of the socket board is to connect the main board to the CRT and to
protect the main board against arc related voltage spikes which originate in the CRT. CC1
The tube socket has built in spark gaps which direct part of the arc energy to the
tube ground (aquadag) through a dissipation resistor 403 403 . The remaining high voltage CC2
from an arc is dropped across current limit resistors: Resistors 404 406 , 406 411
, and and
404
diodes 407 , 408 408 , & 410
410 protect the video amplifiers by directing the arc energy to
capacitor 414 . Since arcing does not normally occur in rapid succession, capacitor 414414 BF
is left to discharge by the leakage current of diodes , 408 , & 410 and zener
407 408 410 5ROM
125
diode 412 is not normally used. The grid pulse transistor is protected by a low pass filter
244
made up of resistors 422 422 & 425 42 and capacitor 423423 . The auto bright transistor 417
417
is protected by resistors 416 416 & 420
420 and by a low pass filter comprised of
resistors 413 , 418 ,&
413 418 415 and capacitor 421 . Resistors 402 & 424 424
reduce the arc energy from the tube ground to signal GND. 3A FUSE
The current gain of the auto bright control loop is set by resistor 420 420 . 245
The filament current is fine tuned by resistor 405 405 .
The degaussing coil 432 432 is energized when power is turned on.
It then rapidly turns off due to the heating of posistor 244 244 .
241
Legend Description PC 115VAC PC
2 INPUT 1 238
No. { Represents the 1492 board part number. The parts list gives the
CERONIX PART NUMBER which is indexed to the board part number.
LTR.No. Part numbers of the resistors on the PRA indicated by LTR. LEGEND
PRA pin number. To determine which PRA the pin number
X X { belongs to, look for the nearest PRA part number on that line. No. BOARD PART No.
LTR.No. PART No. ON PRA.
X- DC voltages are measured to GND except in the power supply X X PRA PIN No.
YV
where V- is the reference. Use a DVM for DC measurements. X- DC VOLTAGE
X-Y VDC RANGE, USING
Y V X-Y VDC
X-Y VDC TIME is the cycle time of the waveform. X-Y VDC
A DMM.
AC VOLTS CYCLE
Vp-p TIME
WAVEFORM
{ The waveform is normally checked with a oscilloscope.
It has a P-P voltage amplitude of Vp-p .
Vp-p TIME
WAVEFORM
Peak to Peak TIME
Measured with scope
CAUTION: When making measurements on the power
supply be sure that the other scope probe is not connected to GND. 21
 BLANKING AND MASTER GAIN CIRCUIT, FUNCTION, DESCRIPTION

Blanking in this monitor is accomplished by reducing the video gain to zero during the
vertical and horizontal blank time. During video time, the gain is set by the master
gain control which is located on the remote control PCB. If the overall beam current
exceeds .75mA for more then ten frames, the beam current limiter circuit will reduce the
video gain to protect the FBT.

SIMPLIFIED GAIN CONTROL CIRCUIT:

GAIN SELECT
+12V RESISTORS VIDEO INTERFACE
1K C5346 +
MASTER GAIN 1K VIDEO GAIN LINE +12V Video To
36 Amp.
58 CRT
485

3.6K 200ý +7.5V

HORIZONTAL BLANKING
PN2222
FLYBACK PULSE One of three input circuits.
0VDC SIGNAL
47V 63uS CONDITIONING
CIRCUIT 104

BEAM CURRENT LIMITER

+6V
BIAS ACTIVE VERTICAL BLANKING
HIGH Z +2V 2 MPSA64 Total
1/2 1 PN2222
5 1N4148 beam current
LM393 D
Vertical Bias O/S 1/2 134 From FBT
7 3 +
LM393 65 10uF
+2V 6 + 63 66
155 .047uF
132

The video P-P voltage amplitude at the cathodes, is the video input signal amplitude times
the master gain control setting times the video amplifier gain. The gain select resistors set
the maximum video gain via the master gain line. For a greater range of brightness,
(highlighting) the video system is allowed to supply high peak video currents which could
damage the FBT if sustained. The beam current limiter circuit insures that the long term
maximum beam current is not exceeded.

Horizontal blanking is achieved by amplifying the flyback pulse (FBP) with transistor 104 . 104
Vertical blanking starts as soon as the LA7851 starts the vertical retrace sequence and is
terminated by the auto bias, bias active signal. A comparator is used to sense the vertical bias
O/S, at pin 16 of the LA7851, which goes low when vertical retrace starts. Capacitor 132 132
holds the vertical blanking active, between the vertical bias O/S pulse, and the bias active pulse.
When the bias active line goes high, the capacitor 132132is reset and vertical blanking ends,
after the bias active line returns to it's high impedance state.

22
 BLANKING AND MASTER GAIN CIRCUIT DESCRIPTION

The master gain control 485 485 is connected to the video gain line through a 1K
resistor 5858 . The voltage range of the video gain line is programmable via resistor 094 094
and solder bridges at SS , TT , & UU which may connect resistors 54 54, 55 55, 56 56, and
57 to the video gain line. This arrangement permits a variety of input signals and
57
picture tubes to be used with the same monitor PCB.

Horizontal blanking ( H )Bis added to the gain line by transistors 104 104. This transistor
pulls down on the gain line through diode 102102when the flyback pulse is high.
Capacitor 197
197 is charged by diodes 105 105 , 106
106 and resistor 112
112 such that, as soon as
the flyback pulse starts going positive the NPN transistor 104 104 turns on and horizontal
blanking starts. The time constant of capacitor 197197and resistors 112 112 and 107 107is
chosen such that the capacitor will lead the FBP on the downward slope and turn the
horizontal blanking transistor off just at the end of the FBP.

Vertical blank time is started when a low going pulse from the LA7851 pin 16 causes
the output, pin 7, of the dual comparator 155155to go low. Capacitor 132 132 is discharged
through resistor 135 135 at this time. After the end of the LA7851 pulse, the capacitor 132 132
holds the output, pin 1 of the comparator, low until the bias active pulse recharges the
capacitor 132
132 through diode 134 134. During the high time of the bias active pulse, the
second comparator output is still low, because of the voltage drop across the diode 134 134 .
The end of vertical blank time occurs when the bias active line returns to it's high
impedance state. The capacitor 132 132 holds the charge from the bias active pulse until the
next vertical blank time.

The video gain line will source up to 32mA during blank time, which is the reason for
buffering the vertical blank comparator with a PNP transistor 139 139 and E-B resistor 129 . 129
Resistors 137137 and 138138 supply a voltage that is midrange relative to the LA7851 pulse
for maximum noise immunity. Resistors 133133and 136136also supply another midrange
voltage for the bias active pulse and the, vertical blanking, hold capacitor to work against.
Resistors 124 and 156 156 are used as jumpers.

The beam current limiter circuit uses the base to emitter voltage of a darlington
transistor 6565 to set the maximum beam current. The beam current is converted to a
voltage across resistor G17
G17 . This voltage is applied to a long time constant RC circuit,
resistor 7070 and capacitor 6666 , before it is sensed by the darlington transistor.
Resistor 65 A has been added to protect the darlington transistor from arc energy.
65A
The sharpness of the limiting response is set by resistors 64 64 and 71 71 .
Transistor 6363 then, reduces the video gain by pulling down on the master gain line
upon excessive beam current.

23
 BLANKING AND MASTER GAIN SCHEMATIC

Remote control PCB

+12V
MASTER
VIDEO GAIN LINE 1K RC2 GAIN 1K
485
058
4.2-8.2VDC GND
5-10 17mS

VERTICAL BLANKING +10V FROM AUTO BIAS SUPPLY

1.8K
6.8K 6.8K
129 (BIAS ACTIVE)
136 138
MPS2907 2 0ý From auto bias IC pin 13
1 1/2 1N4148 124 8 6 1.9-2.3VDC
1.9- 4V 17mS
LM393 2.3V
3 134 7 1/2
139 + LM393
155 5 1.8K
1N4148 + (VERTICAL BIAS O/S)
1.8K 4 156
102 1.8K From LA7851 pin 16
HORIZONTAL 135
133 3.0-3.8VDC
1.8K
6.4-7.5VDC BLANKING .047uF 3V 17mS
8V 63uS 137
1N4148
GND 132

PN2222 106 (FLYBACK PULSE)

6.8K 1K .01uF From FBT pin 8
107 112 0VDC
197
104 47V 63uS
1N4148
105 HB TO AUTO BIAS IC
GND

GAIN SELECT RESISTORS

M C5346
GAIN
036
S T U
1.62K 10K VIDEO INTERFACE IC
909 ý 200ý 412ý
040 094
054 056 057
1.62K
055
+12V
GND

FBT
+6V
BEAM CURRENT LIMITER CIRCUIT.
+6V 270 ý MPSA64 1.8K
PN2222 62K 62K GI7
071 D EHT
065A 070 Return
065 + 10uF
063
750 ý
064 GND 066

24
 Board No.s 001 to 100 REPLACEMENT PARTS LIST Models 1492 and 2092

CERONIX CERONIX
PART No. DESCRIPTION PART No. DESCRIPTION

001 CPR0128 A1 BB9 301 ohm ±1%, .25W .01 051 CPR0141 D1 CC8 4.42K ohm ±1%, .25W .01
002 CPR0124 A1 BB9 75 ohm ±1%, .25W .01 052 CPR0012 C1 CC8 2.7K ohm ±5%, .25W .01
003 CPR0140 B1 CC6 3.92K ohm ±1%, .25W .01 053 CPQ1301 C2 CC8 PN2907 .6A, 40V, .6W, PNP .06
004 CPR0128 B1 AA9 301 ohm ±1%, .25W .01 054 CPR0126 D2 AA5 909 ohm ±1%, .25W .01
005 CPR0124 B1 AA9 75 ohm ±1%, .25W .01 055 CPR0136 D2 AA5 1.62K ohm ±1%, .25W .01
006 CPS1754 C1 6 Conductor Header. .22 056 CPR0127 D2 AA5 205 ohm ±1%, .25W .01
007 CPR0129 A2 BB7 340 ohm ±1%, .25W .01 057 CPR0130 D2 BB5 412 ohm ±1%, .25W .01
008 CPR0144 A2 BB7 12.1K ohm ±1%, .25W .01 058 CPR0009 C2 EE3 1K ohm ±5%, .25W .01
009 059
010 A2 BB8 Optional input filter capacitor. 060 CPC1039 D1 CC8 .1uF ±5% @ 50V .05
011 CPR0128 A2 BB8 301 ohm ±1%, .25W .01 061 CPR0004 D1 DD9 270 ohm ±5%, .25W .01
012 CPD1251 A2 BB8 1N4148 10mA, 75V Diode .01 062 CPR0015 D1 DD8 22K ohm ±5%, .25W .01
013 CPR0140 B1 BB6 3.92K ohm ±1%, .25W .01 063 CPQ1303 D1 PP5 PN2222A .6A, 30V, .5W, NPN .05
014 CPR0131 B2 BB7 464 ohm ±1%, .25W .01 064 CPR0007 D2 PP5 750 ohm ±5%, .25W .01
015 CPR0011 B1 BB6 1.8K ohm ±5%, .25W .01 065 CPQ1302 D2 PP5 MPSA64 .3A, 30V, D-PNP .08
016 CPR0018 B1 BB6 62K ohm ±5%, .25W .01 065A CPR0018 D2 RR5 62K ohm ±5%, .25W .01
017 B1 BB6 Optional -BL adjust resistor. 066 CPC1101 D2 RR5 10uF ±20% @ 50V .04
018 CPR0132 B2 AA7 604 ohm ±1%, .25W .01 067 CPI1410 E1 DD8 LM393 Dual Comparator .31
019 068 CPC1101 E2 GG2 10uF ±20% @ 50V .04
020 CPD1251 B1 AA8 1N4148 10mA, 75V Diode .01 069 CPC1039 D1 PP5 .1uF ±5%, @ 50V .05
021 CPR0128 B2 AA8 301 ohm ±1%, .25W .01 070 CPR0018 E2 RR5 62K ohm ±5%, .25W .01
022 B2 AA8 Optional input filter capacitor. 071 CPR0004 E2 PP5 270 ohm ±5%, .25W .01
023 CPR0144 B2 AA7 12.1K ohm ±1%, .25W .01 072 E1
024 CPR0129 C2 AA7 340 ohm ±1%, .25W .01 073 E1
025 CPC1039 C2 CC8 .1uF ±5% @ 50V .05 074 E1
026 CPR0128 C2 BB9 301 ohm ±1%, .25W .01 075 E1
027 CPR0124 C2 BB9 75 ohm ±1%, .25W .01 076 E1
028 CPR0050 A2 0 ohm Jumper .01 077 CPR0011 E1 EE9 1.8K ohm ±5%, .25W .01
029 078 CPR0009 E2 EE8 1K ohm ±5%, .25W .01
030 CPR0013 A2 AA6 6.8K ohm ±5%, .25W .01 079
031 CPR0129 A2 BB7 340 ohm ±1%, .25W .01 080 CPR0013 E1 DD8 6.8K ohm ±5%, .25W .01
032 CPC1039 A2 AA5 .1uF ±5% @ 50V .05 81B CPR0500 C3 CC1 Blue Video Amplifier 1.12
033 CPR0145 A2 AA6 15.8K ohm ±1%, .25W .01 82B CPC1040 A3 CC1 .015uF ±10% @ 250V .07
034 CPR0144 B3 AA7 12.1K ohm ±1%, .25W .01 83B CPQ1308 A3 CC2 2SC3467AE .1A, 200V, 1W, NPN. .16
035 CPR0129 B2 BB7 340 ohm ±1%, .25W .01 84B CPC1037 C3 DD1 .1uF ±10% @ 250V .07
036 CPI1409 B2 AA6 XRC5346A Custom Video IC 1.51 85B CPR0050 B3 0ý Jumper .01
037 CPR0129 B2 BB7 340 ohm ±1%, .25W .01 86B CPD1251 C3 CC1 1N4148 10mA, 75V Diode .01
038 CPR0129 B2 AA7 340 ohm ± 1%, .25W .01 87B CPQ1309 C3 CC1 2SA1370E .1A, 200V, 1W, PNP .19
039 88B CPC1005 C3 DD2 1000pF ±20% @ 500V .03
040 CPR0136 B2 BB5 1.62K ohm ±1%, .25W .01 89B CPR0006 C3 CC2 510 ohm ±5%, .25W .01
041 C2 BB8 Optional input filter capacitor. 90B CPD1250 C3 DD2 FDH400 .1A, 200V, Diode .03
042 CPD1251 C2 AA8 1N4148 10mA, 75V Diode .01 91B CPQ1309 C3 DD2 2SA1370E .1A, 200V, 1W, PNP .19
043 CPR0128 C2 AA8 301 ohm ± 1%, .25W .01 92B CPR0011 C3 DD2 1.8K ohm ±5%, .25W CF .01
044 CPR0132 C2 AA7 604 ohm ±1%, .25W .01 93B CPR0011 C4 DD2 1.8K ohm ±5%, .25W CF .01
045 CPR0004 D1 DD8 270 ohm ±5%, .25W .01 094 CPR0012 B3 BB5 2.7K ohm ±5%, .25W .01
046 CPR0011 D1 CC8 1.8K ohm ±5%, .25W .01 095 CPC1039 A3 DD3 .1uF ±5% @ 50V .05
047 CPR0011 D1 CC9 1.8K ohm ±5%, .25W .01 096 CPC1039 B3 BB2 .1uF ±5% @ 50V .05
048 CPR0004 D1 DD8 270 ohm ±5%, .25W .01 097 CPR0136 A4 CC3 1.62K ohm ±1%, .25W .01
049 098 CPQ1302 A4 DD3 MPSA64 .3A, 30V, D-PNP .08
050 CPR0009 D1 CC9 1K ohm ±5%, .25W .01 099
100 CPR0134 B4 CC3 1.21K ohm ±1%, .25W .01

25
 Board No.s 101 to 200 REPLACEMENT PARTS LIST Models 1492 and 2092

CERONIX CERONIX
PART No. DESCRIPTION PART No. DESCRIPTION

101 CPD1252 A5 DD5 1N4005 1A, 600V, R-Diode .02 153 CPQ1303 C6 EE9 PN2222A .6A, 30V, .5W, NPN .05
102 CPD1251 A5 AA4 1N4148 10mA, 75V, Diode .01 154 CPR0012 C6 DD9 2.7K ohm ±5%, .25W .01
103 CPD1252 B5 DD5 1N4005 1A, 600V, R-Diode .02 155 CPI1410 C7 BB3 LM393 Dual Comparators .31
104 CPQ1303 B5 AA4 PN2222A .8A, 40V, .5W, NPN .05 156 CPR0011 D7 CC4 1.8K ohm ±5%, .25W .01
105 CPD1251 B5 BB4 1N4148 10mA, 75V, Diode .01 157 CPR0393 D7 MM4 390 ohm ±5%, 2W .04
106 CPD1251 B5 BB4 1N4148 10mA, 75V, Diode .01 158 CPS1755 C2 "RC" 8 Conductor Header .26
107 CPR0013 B4 BB4 6.8K ohm ±5%, .25W .01 159 CPR0011 F3 MM7 1.8K ohm ±5% (Blooming adjust) .01
108 CPC1028 C5 DD6 6800pF ±10% @ 100V .03 160 CPR0050 D2 LL0 0 ohm Jumper .01
109 161 CPC1039 E2 NN8 .1uF ±5% @ 50V .05
110 CPC1028 C5 DD7 6800pF ±10% @ 100V .03 162 CPC1036 E2 MM7 .047uF ±5% @ 50V .04
111 CPC1028 C5 DD7 6800pF ±10% @ 100V .03 163 CPC1032 E2 NN7 .01uF ±5% @ 50V .04
112 CPR0009 D5 BB4 1K ohm ±5%, .25W .01 164 CPR0018 E2 NN8 62K ±5%, .25W (2092 Option) .01
113 165 CPI1405 E2 NN7 LM324 Quad Op. Amp. .31
114 CPS1756 D4 "TC" 10 Conductor Header .29 166 CPR0144 E3 NN7 12.1Ký ±1%.25W (Pin. Adj) 1492 .01
115 CPR0506 C5 "C" PRA (Auto Bias) .68 166 CPR0017 E3 NN7 36Ký ±5%, .25W (Pin. Adj) 2092 .01
116 CPC1036 A5 EE7 .047 uF ±5% @ 50V .04 166A CPR0018 E3 NN7 62Ký ±5%, .25W (H. Ras. Adj.) .01
117 CPC1039 B5 EE7 .1 uF ±5% @ 50V .05 167 CPR0168 E3 NN7 8.06Ký ±1%.25W (Pin. Adj) 1492 .01
118 CPC1036 B5 EE7 .047uF ±5% @ 50V .04 167 CPR0015 E3 NN7 22Ký ±5%, .25W (Pin. Adj) 2092 .01
119 168 CPC1032 E3 PP8 .01uF ±5% @ 50V .04
120 CPC1039 B5 EE6 .1uF ±5% @ 50V .05 169 CPC1102 E2 MM7 100uF ±20% @ 25V .05
121 CPC1036 B5 EE6 .047uF ±5% @ 50V .04 170 CPR0504 F3 "G" PRA (H. Width Control) .92
122 CPC1039 B5 EE6 .1uF ±5% @ 50V .05 171 CPR0013 F3 MM8 6.8K ohm ±5%, .25W .01
123 CPI1402 A6 FF7 CA3224E Auto Bias IC 1.95 172 CPR0142 E3 NN5 7.15K ohm ±1%, .25W .01
124 CPR0050 A6 CC3 0 ohm Jumper. .01 173 CPR0050 D3 GG4 0 ohm Jumper .01
125 CPC1101 B6 FF7 10uF ±20% @ 50V .04 174 CPR0050 D3 GG1 0 ohm Jumper .01
126 CPC1101 B6 FF6 10uF ±20% @ 50V .04 175 CPR0050 D3 GG2 0 ohm Jumper .01
127 CPC1101 B6 FF6 10uF ±20% @ 50V .04 176 CPR0144 D3 EE8 12.1K ohm ±1%, .25W .01
128 CPC1039 A7 EE3 .1uF ±5% @ 50V .05 177 CPR0050 E3 0 ohm Jumper .01
129 CPR0011 A6 AA3 1.8K ohm ±5%, .25W .01 178 CPR0009 E3 NN5 1K ohm ±5%, .25W .01
130 CPI1407 A7 EE3 NJM7812FA 12V, 1A,Regulator. .30 179 CPR0024 F3 MM7 3.3Ký ±5% .25W (Max. iBeam adj.) .01
131 CPC1104 B7 JJ6 1000uF ±20% @ 35V .22 180 CPQ1308 E4 MM2 2SC3467F .1A, 200V, 1W, NPN .16
132 CPC1036 B7 BB4 .047uF ±5% @ 50V .04 181 CPR0050 E3 GG1 0 ohm Jumper .01
133 CPR0011 C7 BB4 1.8K ohm ±5%, .25W .01 182 CPR0351 E3 NN3 150 ohm ±10%, .5W, CC .05
134 CPD1251 C7 BB3 1N4148 10mA, 75V, Diode .01 183 CPC1041 E4 MM5 .33uF ±5% @ 50V .08
135 CPR0011 C7 BB4 1.8K ohm ±5%, .25W .01 183A CPR0050 E3 0 ohm Jumper .01
136 CPR0013 C7 BB3 6.8K ohm ±5%, .25W .01 184 CPR0143 E3 NN6 10.0K ohm ±1%, .25W .01
137 CPR0011 C7 CC4 1.8K ohm ±5%, .25W .01 185 CPQ1307 F3 PP8 2SC4159E 1.5A, 180V, 15W, NPN .36
138 CPR0013 C6 CC3 6.8K ohm ±5%, .25W .01 186 CPM2037 G3 PP8 Heat Sink, H. Width output .11
139 CPQ1301 A6 AA3 MPS2907 .6A, 40V, .6W, PNP .06 187 CPC1036 D4 GG3 .047uF ±5% @ 50V .04
140 CPR0050 C6 0 ohm Jumper .01 188 CPM2036 E4 GG1 Heat Sink, V. Deflection out .13
141 CPR0016 C6 GG6 33K ohm ±5%, .25W .01 188A CPM2037 GG1 Heat Sink (2092 Option) .11
142 CPR0016 C6 GG7 33K ohm ±5%, .25W .01 189 F4 .01
143 CPR0016 C6 GG7 33K ohm ±5%, .25W .01 190 CPD1252 E4 KK1 1N4005 1A, 600V, R-Diode .02
144 CPC1039 B6 EE5 .1uF ±5% @ 50V .05 191 CPC1109 E4 KK1 470uF ±20% @ 50V .19
145 CPD1252 C5 DD5 1N4005 1A, 600V, R-Diode .02 192 CPI1401 E4 HH1 LA7830 Vert. Def. Output .67
146 CPI1405 C5 GG6 LM324 Quad Op. Amp. .31 193 CPR0377 F4 GG2 3.3 ohm ±5%, 1W .03
147 CPR0015 C6 GG6 22K ohm ±5%, .25W .01 194 CPR0050 F4 0 ohm Jumper .01
148 CPR0015 C6 GG6 22K ohm ±5%, .25W .01 195 CPC1104 G4 MM2 1000uF ±20% @ 35V .22
149 196 CPR0391 D5 JJ2 200 ohm ±5%, 2W .04
150 CPC1039 C6 GG5 .1uF ±5% @ 50V .05 197 CPC1032 D5 BB4 .01uF ±5% @ 50V .04
151 CPR0050 D6 0 ohm Jumper .01 198 CPC1000 D5 EE4 56pF ±5% @ 100V .03
152 CPR0016 C6 EE8 33K ohm ±5%, .25W .01 200 CPR0157 E5 HH2 127K ohm ±1%, .25W .01

26
 Board No.s 201 to 300 REPLACEMENT PARTS LIST Models 1492 and 2092

CERONIX CERONIX
PART No. DESCRIPTION PART No. DESCRIPTION

201 CPC1101 E5 MM5 10uF ±20% @ 50V .04 252 CPD1264 H1 GG8 FR205 2A, 600V, F-Diode .04
202 CPC1043 E5 GG2 1.0uF ±5% @ 50V .17 252A CPC1003 H1 GG7 2,200pF ±20% @ 1KV .03
203 CPR0017 E5 MM5 36K ohm ±5%, .25W 1492 .01 253 CPD1264 H1 GG8 FR205 (220V Option) .04
203 CPR0163 E5 MM5 28.0Ký ±1%, .25W 2092 .01 254 CPD1264 H2 GG9 FR205 2A, 600V, F-Diode .04
204 CPC1000 F5 JJ1 56pF ±5% @ 100V .03 254A CPC1003 G2 GG7 2,200pF ±20% @ 1KV .03
205 CPC1005 F5 JJ2 1000pF ±20% @ 500V .03 254B CPR0050 H2 0 ohm Jumper .01
206 CPC1058 F5 HH2 .1uF ±5% @ 50V .05 255 CPD1264 H2 GG9 FR205 (220V Option) .04
207 CPC1032 F5 HH2 .01uF ±5% @ 50V .04 256 CPC1105 H1 HH8 150uF ±20% @ 250V .88
208 CPC1002 F5 II1330pF ±10% @ 100V .03 257 CPC1105 H2 HH8 150uF ±20% @ 250V .88
209 CPC1032 F5 NN2 .01uF ±5% @ 50V .04 258 CPT1503 J1 KK6 Switch Mode Transformer 2.10
210 CPC1036 F5 JJ2 .047uF ±5% @ 50V .04 259 CPR0050 I1 0 ohm Jumper .01
211 F5 Vertical Deflection Bias Adj. 260 CPD1264 J1 KK5 FR205 2A, 600V, F-Diode .04
212 F5 Vertical Deflection Bias Adj. 261 CPC1039 J2 KK6 .1uF ±5% @ 50V .05
213 CPS1759 G5 4X .062 Dia. Bead Pins (YC) .01 262 CPC1039 J2 JJ6 .1uF ±5% @ 50V .05
214 CPR0503 F5 HH2 "H" PRA Vertical Control 1.26 263 CPD1264 J2 JJ5 FR205 2A, 600V, F-Diode .04
215 CPC1104 D6 JJ6 1000uF ±20% @ 35V .22 264 CPR0351 I2 KK9 150 ohm ±10%, .5W, CC .07
216 CPC1102 D6 GG3 100uF ±20% @ 25V .05 265 CPC1006 I2 KK8 200pF ±10% @ 1KV, NPO .04
217 266 CPD1264 I2 KK6 FR205 2A, 600V, F-Diode .04
218 CPI1400 E6 KK3 LA7851 V. & H. Control IC 1.48 267 CPM2027 J3 LL8 HEAT SINK , Power Supply .08
219 268 CPQ1304 J3 KK8 2SK1446LS 450V, 7A, MOS FET .94
220 CPC1036 F5 II1 .047uF ±5% @ 50V .04 269 CPR0050 J3 0ý Jumper, to ground PS H. S. 267 .01
222 CPR0502 F6 KK4 "I" PRA Horizontal Control .68 270 CPR0002 I2 KK8 18 ohm ±5%, .25W .01
223 CPD1257 D6 JJ2 1N4742 12V ±5%, 1W, Z. DIODE .05 271 CPR0147 I3 KK7 1.0 Meg ohm ±1%, .25W .01
224 CPR0002 D6 GG3 18 ohm ±5%, .25W .01 272 CPR0501 I3 "J" Power Supply PRA .68
225 CPC1102 D6 GG3 100uF ±20% @ 25V .05 273 CPR0011 G3 HH7 1.8K ±5%, 127V line adjust. .01
226 CPC1026 E6 HH4 1000pF ±5% @ 100V .06 274 CPC1028 G3 HH7 6800pF ±10% @ 100V .03
227 CPC1025 E6 HH4 330pF ±5% @ 100V .06 275 CPC1000 G3 II7 56pF ±5% @ 100V .03
228 CPC1028 E6 II4 6800pF ±10% @ 100V .03 276 CPC1000 G3 HH7 56pF ±5% @ 100V .03
229 277 CPC1027 G4 HH8 6800pF ±5% @ 100V .06
230 CPC1100 E6 II4 1uF ±20% @ 50V .04 278 CPR0050 G4 PP8 0 ohm Jumper .01
231 CPC1032 F6 JJ4 .01uF ±5% @ 50V .04 279 G3 HH8 Power Supply Fo Adjustment.
232 CPC1027 F6 JJ4 6800pF ±5% @ 100V .06 280 CPI1403 H4 II6-8 XRC5184 Custom P. S. IC 1.91
233 CPC1100 F6 JJ4 1uF ±20% @ 50V .04 281 CPC1032 H3 HH6 .01uF ±5% @ 50V .04
234 CPC1003 F6 MM3 2,200pF ±20% @ 1KV .03 282 CPC1003 H3 JJ9 2200pF ±20% @ 1KV .03
235 CPR0138 F7 KK4 2.05K ohm ±1%, Hfo adjust. .01 283 CPD1252 H3 KK8 1N4005 1A, 600V, R-Diode .04
236 CPQ1307 F7 MM3 2SC4159E 1.5A, 180V, 15W, NPN .36 284 CPQ1302 H3 KK9 MPSA64 .3A, 30V, D-PNP .08
237 CPT1505 E7 NN3 Horizontal Drive Transformer .60 285 CPC1039 I3 JJ7 .1uF ±5% @ 50V .05
238 CPS1753 F1 GG9 "PC" 2 Conductor Header .21 286 CPC1102 H3 HH9 100uF ±20% @ 25V .05
239 F1 GG9 Optional AC noise capacitor. 287 CPR0169 I3 KK7 191K ohm ±1%, .25W .01
240 CPR0426 F1 GG9 C-200-7, 25-.5ý Inrush Current Limiter .28 288 CPC1002 I4 II8 330pF ±10% @ 100V .03
241 F2 GG9 Optional AC line capacitor. 289 CPR0050 G3 RR4 0 ohm Jumper .01
242 CPS1758 F2 "CC" .093 Dia. Bead Pins .02 290 CPD1251 I4 LL7 1N4148 10mA, 75V, Diode .01
243 CPS1758 F2 "CC" .093 Dia. Bead Pins .02 291 CPC1026 I3 KK7 1000pF ±5% @ 100V .06
244 CPRO427 F3 LL9 BF5ROM125 Posistor (Optional) .96 292 CPR0376 I3 KK9 1.2 ohm ±5%, 1W .03
245 CPR0425 F3 GG9 SS1-3A 3 AMP FUSE .25 293 CPD1264 J3 MM4 FR205 2A, 600V, F-Diode .04
246 CPRO430 G1 LL9 Dual Posistor (Optional) 294 CPC1037 J3 II5 .1uF ±10% @ 250V .07
247 CPR0366 G2 HH8 100K ohm ±5%, .5W, CF .01 295 CPD1256 J3 II5 TZ160B-T3 160V ±5%, 1W,Z-Diode .18
248 CPD1264 G2 KK6 FR205 2A, 600V, F-Diode .04 296 CPC1034 I4 JJ6 .022uF ±5% @ 630V .08
248A CPR0002 G2 JJ6 18 ohm ± 5%, .25W .01 297 CPT1500 I5 PP3 Flyback Transformer 10.64
249 G2 HH6 Optional 127V line control. 298 CPR0356 G5 PP6 2.2Ký ±10%, .5W, CC 1492 .07
250 CPQ1310 G3 HH6 2SA1371E .1A, 300V, 1W, PNP .22 298 CPR0353 G5 PP6 1Ký ±10%, .5W, CC 2092 .07
251 CPR0019 H3 HH6 100K ohm ±5%, .25W .01 300 CPC1035 G5 PP6 3,300pF ±5% @ 200V .06

27
 Board No.s 301 to 490 REPLACEMENT PARTS LIST Models 1492 and 2092

CERONIX CERONIX
PART No. DESCRIPTION PART No. DESCRIPTION

301 CPT1523 G5 PP7 220uH Horz. Width Coil. 1492 .60

301 CPT1506 G5 PP7 Horz. Linearity Coil 2092 .60 REMOTE CONTROL BOARD
302 CPT1506 G6 PP6 Horz. Linearity Coil .60 CPA4102 Remote PCB Assembly. 4.75
303 CPR0392 F7 NN4 270 ohm ±5%, 2W .04 485 CPR0400 FF2 1K ohm White Pot .17
304 CPQ1305 G7 NN3 2SD1651 5A, 1.5KV, NPN 1.48 483 CPR0401 FF2 1K ohm Blue Pot .17
305 CPC1050 H6 RR7 .47uF ±5% @ 250V 1492 .36 481 CPR0402 FF1 10K ohm Yellow Pot .17
305 CPC1059 H6 RR7 .33uF ±5% @ 250V 2092 .38 484 CPR0403 FF2 20K ohm Orange Pot .17
306 CPC1030 H6 RR6 .01uF ±3% @ 1.6KV 1492 .26 482 CPR0405 FF1 500 ohm Black Pot .17
306 CPC1055 H6 RR6 8,200pF ±3% @ 1.6KV 2092 .37 486 CPR0007 FF1 750 ohm ±5%, .25W .01
307 CPC1034 H7 RR8 .022uF ±5% @ 630V .08 487 CPS1767 "RC" 8 Conductor Cable .87
308 CPD1252 I6 RR6 1N4005 1A, 600V, R-Diode .02
309 CPR0365 H7 NN4 470 ohm ±5%, .5W, CF .01
310 CPD1252 I6 RR7 1N4005 1A, 600V, R-Diode .02 PCB ASSEMBLIES
311 CPD1253 I6 RR8 1N4937 1A, 600V, F-Diode .03 CPA4100 1492 Main PCB Assembly 105.00
312 CPD1264 J6 NN4 FR205 2A, 600V, F-Diode .04 CPA4103 2092 Main PCB Assembly 115.00
313 CPR0050 J6 0 ohm Jumper .01 CPA4101 CRT P.C. Board Assembly 7.50
314
315 CPC1044 I6 PP8 2.7uF ±10% @ 100V .32
316 CPT1504 I7 PP7 Horizontal Width Coil .63
317 CPC1105 J7 II5 150uF ±20% @ 250V .88

TUBE SOCKET BOARD

401 CPS1750 CRT SOCKET 1.54
402 CPR0350 NN1 47 ohm ±10%, .5W, CC .07
403 CPR0352 NN1 470 ohm ±10%, .5W, CC .07
404 CPR0353 NN0 1K ohm ±10%, .5W, CC .07
405 CPR0375 PP1 .68 ohm ±5%, 1W 1492 .03
405 CPR0050 PP1 0ý Jumper 2092 .01
406 CPR0353 NN1 1K ohm ±10%, .5W, CC .07
407 CPD1250 MM0 FDH400 .1A, 200V, Diode .03
408 CPD1250 MM0 FDH400 .1A, 200V, Diode .03
409
410 CPD1250 MM0 FDH400 .1A, 200V, Diode .03
411 CPR0353 NN0 1K ohm ±10%, .5W, CC .07
412
413 CPR0353 PP1 1K ohm ±10%, .5W, CC .07
414 CPC1040 MM1 .015uF ±10% @ 250V .07
415 CPR0355 NN1 100K ohm ±10%, .5W, CC .07
416 CPR0019 MM1 100K ohm ±5%, .25W, CF .01
417 CPQ1306 MM1 2SC3675 .1A, 1.5KV, NPN .67
418 CPR0353 PP1 1K ohm ±10%, .5W, CC .07
419
420 CPR0029 MM1 200K ohm ±10%, .25W, CF .01
421 CPC1003 PP1 2200pF ±20% @ 1KV .03
422 CPR0353 PP1 1K ohm ±10%, .5W, CC .07
423 CPC1002 PP1 330pF ±10% @ 100V .03
424 CPR0350 NN1 47 ohm ±10%, .5W, CC .07
425 CPR0354 NN1 10K ohm ±10%, .5W, CC .07
426 CPS1769 10 Conductor Cable .83
CPS1768 10 Conductor Cable, Double length. .99
427 CPS1758 .093 Dia. Bead Pin .02

28
 Block Diagram Review

GAME
3 VIDEO 3
VIDEO 3
Beam 3
VIDEO AMPS. Current
Interface
Feedback
CRT
A Bias B
C G
3
SYNC BLANKING 3 Auto V DY
F.B.P. Bright
V retrace F 3 H DY
Beam limit 3
M. gain D
H AUTO BIAS Beam current
IC buffer
SYNC
Interface I H. blank Program pulse
V. blank Grid pulse
2
E

Vs VERTICAL VERTICAL
CONTROL OUTPUT
I. V. Feedback High Efficiency
J L

VERTICAL
AUTO BIAS
K
EHT

HORIZONTAL H. H. FBT
CONTROL Driver Output
Hs Sync delay N O P
H. Pos. M
V. Size & PINCUSHION
V. Ras. Pos. 2

REMOTE HORIZONTAL DIODE

CONTROLS Size Control Modulator
(PCB) Q R S
Beam Current

+127V

ISOLATION VOLTAGE LOAD (VIDEO & DEFLECTION)

Transformer DOUBLER V
Raw DC
(IN GAME) 320V +12V
T SWITCHING +16V Video
Regulator
REGULATOR +27V Supply
V- -200V W
Sync U
+12V Deflection
Zener Supply
OVER X
VOLTAGE
PROTECT
Y
31
 AUTO BIAS AND AUTO BRIGHT CIRCUIT, FUNCTION, DESCRIPTION
The auto bias circuit is a control system that forms a closed loop for controlling the CRT bias
voltage. It generates a set of conditions where the current near the cutoff voltage of each gun
is measured, and then adjusts the bias voltage of the video amplifiers, to set the correct black
level voltage for each gun. This color balance adjustment is necessary, since each gun in the
color picture tube can have a different cutoff voltage, which also, will change as the CRT ages.
If the picture tube gain changes, the auto bias circuit would adjust all three guns in the same
direction to maintain constant black level. This effect reduces the auto bias voltage range which
is needed for the cathode differential voltage adjustment. To prevent this occurrence a second
control loop is added to the system. This second control loop is called the auto bright circuit and
corrects for CRT gain changes. The auto bright circuit senses any common bias voltage change
and controls the screen grid (G2) to hold the common bias voltage constant.
SIMPLIFIED PICTURE TUBE VIDEO BIAS CONTROL CIRCUIT: (One channel shown)
+ R
VIDEO Video G
INTERFACE Amp. B CRT
CA3224E
123 G1 G2
.1uF 10uF
Beam Red input Red + Auto Bright FB
Current A hold Amplifier
Buffer 5K B 4.2V Scre
122 cap. 127 + ad
SW C 8*
normal LM324
LM324 comp. R 33K
4.2V
+ 200 ý .047uF V ref.
G 33K 22K
C8 GREEN CHANNEL 100K

B 33K
68.1K BLUE CHANNEL 2.7K +10V
V sync Grid pulse
Counter, Decoder
H sync Control Logic Program
Pulse
* Adjust, FBT bottom pot, for 4.6V at pin 8.
Note; All XX92 boards have a solder connection o
C thick films, with a solder connection in the midd
The auto bias circuit performs all of its sensing and bias corrections during the sixteenth to
the twenty first horizontal cycle, after the vertical blanking has started. Before the sixteenth
cycle, the SW in the auto bias IC is open ( SW in "C" position).
During the 16,17, and 18 horizontal cycle, the CRT is brought out of cutoff by the grid
pulse. The resulting beam current produces a voltage at the beam current buffer output.
This voltage is applied to the coupling capacitor 122122
. At the other side of the coupling
capacitor is the channel input, which is clamped to V ref. (SW in "A" position). The voltage
amplitude of the amplifier output with the cathode current information is then stored in the
coupling capacitor 122
122 during this time.

During the next three horizontal cycles (19, 20, and 21), the SW is switched to pass
current to capacitor 127127 which is the bias voltage storage capacitor. At the same time a
program pulse is applied to resistor C8C8 which, if the bias was correct during the previous
cycle, exactly balances the voltage stored in the coupling capacitor and no difference is
sensed at the channel input. The channel amplifier, in this case, does not output current
and the voltage of capacitor 127127 stays unchanged.

If the CRT cathode is too far into cutoff, less beam current flows, the beam current buffer
puts out a smaller negative pulse, less voltage is stored in the coupling capacitor, the
program pulse amplitude (which is constant) is now larger than the stored (beam current)
voltage and the channel amplifier will add current to the bias voltage, storage capacitor
127 , correcting the low bias voltage which caused the cathode to be too far into cutoff.
After the program pulse is over, the SW is switched to the open position again and the
next time the bias voltage can be adjusted is during the next vertical blank time. 32
 AUTO BIAS AND AUTO BRIGHT CIRCUIT DESCRIPTION

The beam current feedback circuit uses a PNP video transistor 91R91R to direct most of
the beam current to the auto bias circuit while passing the voltage waveform, from the
video amplifiers to the CRT cathodes. Diode 90R 90Rand capacitor 88R 88Rinsure that no
video waveform distortion occurs. An additional benefit of this circuit is that it protects
the video amplifiers from the destructive arc energy. Resistors 92R92R and 93R 93R divide
energy due to CRT arcing, between the video amplifier transistors and the beam current
feedback transistor 91R91R . The beam current is filtered by capacitor 108 108and resistor
C10 and is buffered by an operational amplifier, which translates the beam current into
C10
a low impedance voltage. This voltage is applied to a coupling capacitor 122122 through a
200 ohm resistor C8 C8 . The 200 ohm and the 68.1K resistor C3 C3 forms the program
value which sets the black level voltage via the action of the program pulse.
Capacitor 121
121 is used to stabilize the transconductance amplifier which is used at the
channel input of the auto bias IC 123123. The auto bias IC stores the bias voltage of this
channel in capacitor 127127 at pin 21. This voltage is buffered by an internal amplifier,
with output at pin 20, which is connected to the Red video amplifier bias input.

Resistor 141141 , 142

142 , and 143143 are part of the auto bright circuit. They are used to
sum the bias voltage of each of the three channels via a voltage node at the auto
bright amplifier, 146146pin 9. The resulting output voltage then controls the screen
grid via transistor 417417. Resistors 413 413and 418418protect the CRT from excessive
current during arcing. Capacitor 423423supplies a low AC impedance to GND to
insure that the CRT gain is constant during each horizontal line.
Resistor 420420 defines the current gain of, and stabilizes, the auto bright control loop.
Resistor 148148 and capacitor 150 150 act as a low pass filter to reduce the chance of
damaging the amplifier 146 146 due to CRT arcing. Resistors 415415 , and 416416protect
the auto bright control transistor 417417 . The grid pulse is generated by a discrete
transistor 153153 to protect the auto bias IC from possible arc energy.
Pullup resistor 154 154 supplies the grid pulse voltage during the grid pulse time.
The auto bias IC (CA3224E) is designed for a supply voltage of +10V and since the
video amplifier requires +12V, three diodes 101101 , 103103, and 145145are used to supply
this IC. Resistors C4C4 and C7C7 form a voltage divider which supplies the bias
voltage to the LM324 146 146. The green and blue channel circuits are identical to the
red channel and are controlled by the timing logic in the same way. Refer to the
waveforms at the bottom left of page 34 for the timing relationship. The vertical
retrace pulse, from the LA7851, starts the 21 count auto bias state counter. The
grid pulse becomes active between the 15 and 18 horizontal cycle and the program
pulse is active between the 18 and 21 horizontal cycle. These two pulses in
conjunction with the internal control of the transconductance amplifier output switch
are what measure and set the video bias.

33
 AUTO BIAS AND AUTO BRIGHT SCHEMATIC
10K 1K G1
R
425 422 1000pF G
B CRT
330pF AUTO BRIGHT CIRCUIT
88R
421 +4.2V 10 2SC3675 100K 1K 1K G2
FDH400 +
1/4 8 22K 100K
2.2K LM324 415 418 413
90R
VIDEO 2SA 1370 92R 9 148 416
+ 146 417 4,700pF Green, Blue
INTERFACE Video .1uF 100K 423 Video BIAS
Amp. 22K 150 420
LINES
91R 2.2K 147

Red BEAM CURRENT 93R

Red video BIAS control line.

Green & +12V Video Supply 1N4001 1N4001 1N4001

+10V AUTO BIAS CIRCUIT
10
Blue BEAM
CURRENT 2.74K 101 103 145
C7 11 .1uF
5 AUTO BIAS IC
146 144
1.82K
+ 1 GND Vcc 22
1/4 7
C4 LM324 CA3224E
6 12 200ý 123
4K
13
C8 7 .1uF 2 Red input Red 21 10uF
+
C10 5K
14 5.8- hold
6,800pF 68.1K 122 6.4V cap. 127
C9
108 3 C3 sw.
.047uF normal 2.5- 33K
+ 3 20 6.7V
1/4 1 1.2- comp.
LM324 121 141
2.5V
15 2 17 200ý sw. in grid pls. pos.
4K 10uF
C13 5 .1uF 4 Green input Green 19 +
16 5K
C11 hold
5.8-
6,800pF 68.1K 120 6.4V cap. 126
C12
sw.
110 12 C2
.047uF 2.5- 33K
+ 5 18 6.7V
1/4 14 1.2- comp.
LM324 118 142
13 2.5V
18 4K 20 200ý
.1uF 10uF
19 C16 4 6 Blue input Blue 17 +
C14 5K
5.8- hold
6,800pF 68.1K 117 6.4V cap. 125
C15
111 sw.
C1 1 2.5-
.047uF 7 16 33K
GND 6.7V
1.2- comp.
V. RETRACE 116 143
V. Retrace 2.5V
6V REF.
V. Blanking 33K 8 15
CL BIAS
H. Blanking 152 .1- START
1 18 .3V 4.6-5.2VDC
COUNTER
Bias active FF Q
Grid pulse 8 9 GND 14
5V REF
Program pulse 20K EN
8.0-9.0VDC C5 21 H. LINE AUTO
8.4V 17mS +10V HB 2,9 10 COUNTER BIAS 13 To vertical blanking
Grid pulse CL
ACTIVE
6.3- 1.9-2.3VDC
2.7K .5-.8VDC 7.7V DECODER 4V 17mS
154 PN2222 .7V 17mS sw. control
To CRT Grid #1
11 GRID PROGRAM 12
153 PULSE PULSE
GND

34
 VERTICAL AND HORIZONTAL SYNC CIRCUIT DESCRIPTION
The 1492 Monitor has a separate input for horizontal and vertical sync. The horizontal
sync pulse is normally positive going. The horizontal deflection control circuit will sync
on the rising edge of this pulse. If horizontal sync is negative going, the picture is shifted
to the left, and may be out of range of the horizontal picture position adjustment circuit.
To sync on the falling edge of horizontal sync, a solder bridge is installed on the I PRA.

The vertical deflection circuit will sync on either a negative or positive sync pulse,
provided that the pulse width is between two and twenty horizontal cycles long. Both the
vertical and horizontal sync lines are joined for composite sync operation.

VERTICAL AND HORIZONTAL SYNC CIRCUIT

VIDEO +12V DEFLECTION +12V
1K
22K 12K
78
62 56pF 1.8K I2 1 Horizontal
6.8K
Sync input
1.8K 3 8 80
198 I1
+
46 1/2 1 12K
LA7851
270ý LM393
45 2 176 Deflection
67 8.8K 22K Control IC
GND
5 I12 I3
+ 10uF
270ý 1/2 7 1.8K + 19 Vertical
48 LM393 Sync input
1.8K 6 77 68
47 .14-.16V
4
270 ý .047uF
61 187

GND
HORIZONTAL
SYNC
Hs V s
VC VC VERTICAL
1 2 SYNC
This sync interface incorporates a dual voltage comparator 67 67 and a resistive input
circuit for high reliability. For TTL level sync signals, the resistive inputs are seven to one
attenuators comprised of resistors 4545 , 46 , 47 47 , and 48 . The comparators are
biased to .15 volts by resistors 6161 , 62 62 which permit direct connection to an RS170
sync source by removing resistors 4545 and 48 .
The horizontal sync signal from the comparator output is pulled up by resistor 80 and 80
attenuated by resistor 176 176 and I1 I1 , for correct drive amplitude. It is differentiated by
capacitor 198 198 and applied to the horizontal sync input, pin 1, of the LA7851.
Bias resistors I2I2 and I3I3 set up the correct voltage for positive edge triggering.
By adding resistor I12 I12, the LA7851 is programmed for negative edge triggering.
This is used when the horizontal sync pulses are negative going. Resistor I12 I12is connected
by adding a solder bridge to the I PRA solder pads above pin 6.
The vertical sync signal from the second comparator is coupled to the LA7851, vertical sync
input, via a coupling capacitor 68 68. Resistor 77 77and capacitor 187187form a low pass
filter to eliminate false triggering by horizontal sync pulses in the case of composite sync.
Resistor 78 78 and capacitor 77 77 compliments the comparator open collector output by
acting as a pullup. These resistors also form a voltage divider which insures that the
capacitor 68 68 is not reverse biased and provide the proper vertical sync drive amplitude.
The LA7851 vertical sync input circuit is designed to accept either positive or negative sync
pulses, but will not work with a sync signal that is close to a square wave.
35
 VERTICAL DEFLECTION CIRCUIT, FUNCTION, DESCRIPTION
The LA7851 IC and the H PRA have all the active components to control the vertical deflection.
LA7830 is a high efficiency vertical yolk driver IC. Together they form a compact and efficient
vertical deflection system.
34K SIMPLIFIED VERTICAL DEFLECTION CIRCUIT
.047uF V. Auto Bias on H PRA +12V VERT. YOLK
22K 22K 200K
+ 1000uF
76.8K
330 ý
H6
+12V 118K +
22K 10uF
301ý 1uF 330 ý V SIZE
500 ý 3.3 ý
.01uF 202 193
+24V LINE
17 16 6
220uF RETRACE
S Q CONTROL
18 V. + 7 BOOSTER
OSC FF
.1uF R Q 5V 3 LA7830
COMP. 192

+ or -
LA7851 AMP. OUTPUT 2
V SYNC 19 VERT. 15 4
218 3.4V
SYNC

The vertical oscillator supplies the start time for the vertical cycle and when vertical sync
is present, sync supplies the start time to the vertical oscillator. The linear vertical ramp
current which is necessary for linear vertical deflection is generated by supplying a
capacitor 202
202 with a constant current from resistor H6 H6 , at a voltage node (pin 16).
The voltage at this node is held constant by a system of amplifiers which drive the deflection
yoke. The yoke current sensing resistor 193 193is connected to the other side of this capacitor
202 and supplies the ramp voltage which balances the current from
202 during trace time.
H6 H6

To generate the other half of the deflection yoke sawtooth current (vertical retrace),
a flip flop is set by the vertical oscillator which partly discharges the capacitor 202 202
and causes the drive voltage across the yoke to reverse. The amount of discharge of
capacitor 202 202 determines the vertical output voltage for the next cycle and is controlled by a
timer at pin 17. The time out of the timer is controlled by the vertical output voltage from two
different paths. One path is through the 34K and 118K resistors which supplies the higher
frequency component for the timer and stabilize the vertical amplifier. The other path is
through the vertical auto bias circuit which detects the minimum vertical output voltage over
many vertical cycles and supplies a second current source to the timer. This second current
source has a wide dynamic range and will hold the vertical output voltage well within operating
limits for both 50Hz and 60Hz with no need for manual adjustment.

To better understand the LA7851 bias control loop, imagine the vertical output voltage
goes up, the time out shortens which causes the capacitor 202 202to be less discharged. This
raises the voltage on capacitor 202
202 and lowers the vertical output voltage. This type of
vertical bias control system has the advantage of only correcting the bias during retrace
which means that it will not cause current ramp distortion during vertical trace time.

The vertical yoke driver LA7830 is the power output stage for the vertical amplifier.
It has a built-in voltage booster circuit to reduce vertical retrace time without
the power losses associated with a high vertical supply voltage.
36
 HORIZONTAL RASTER WIDTH CONTROL CIRCUIT DESCRIPTION
The purpose of the horizontal width control circuit is to:
1. Provide a convenient means for adjusting the horizontal raster size.
2. Correct pincushion distortion in the vertical axis.
3. Correct horizontal raster distortion caused by periods of high beam current.
The horizontal width control circuit is comprised of two main parts; The control circuit and
the diode modulator (DM). The control circuit combines four signals in the monitor to produce
the width control circuit. These signals are:
1. Horizontal size From the H. Size Pot.
2. Vertical current (Iv) From the 3.3 ohm vertical current feedback resistor.
3. Vertical parabolic + Iv From the vertical yoke return.
4. Beam current From the EHT return on the FBT.
The diode modulator controls the horizontal yoke current which affects the horizontal size. This is
accomplished by controlling the start time of the flyback pulse in the diode modulator node at the
cathode of 311 311 . The start time of this pulse is then a function of the forward current of the
diode 311 311 . This is because the current in the pulse across capacitor 306306must exceed the current in
the diode 311 before the pulse in the diode modulator node can start. The current used to control the
start time of the pulse comes from the voltage across inductor 316 316from the previous horizontal pulse
and is controlled by the control circuit.
The horizontal size voltage from the remote control PCB 490490is applied directly to the control
amplifier summing node (LM324 Pin 12) by resistor G11G11 . For pincushion correction, the vertical
parabolic voltage is needed, but it is not directly available since the vertical current,voltage (Iv) is part
of the vertical parabolic voltage with respect to GND. The + Iv from the current sensing
resistor 193 193 , is inverted by an Op Amp and resistors 148184 and 1 72172. Resistor G 3 G3level shifts the
inverted Iv to + 6V. The (vertical parabolic + Iv) is AC coupled by capacitor 183 183 and resistor G6 .G6
It is then amplified by an Op Amp connected as a voltage follower. Resistor G7 protects the Op Amp
G7
against arc related voltage spikes. The inverted Iv (-Iv) and (parabolic voltage +Iv) are added to the
amplifier node by resistors 1 167 6 and 166 166 which then makes up the pincushion correction signal.
The beam current from the FBT is converted to a voltage by resistors G17 , adj. 159
G17 159 & adj. 179 and
is filtered by capacitor 162 162 . Resistor G12 G12 then connects the signal to the width control amplifier
node which accomplishes the blooming control function. The control amplifier converts the current at
the summing node (LM324 Pin 12) to a voltage across capacitor 315315, via feedback resistor G13G13 .
A power transistor 185 185 is necessary since up to 2 watts may be dissipated by the control amplifier.
Resistor G15 and capacitor 163 163 & 16168 set the AC gain of the control Op Amp for stable operation.
Resistor G14 G14 stabilizes the complete control amplifier by reducing the overall gain. Resistors G 9 ,G9
G10
G 10 , 1164
64 and 166A166A provide adjustment for setting the horizontal size range. The fourth Op Amp of
the LM324 and resistors G G1 1 and G G2 2 are used to generate a +6 volt ref. voltage for the control
circuit. Resistor 1171 71 stabilizes this +6V line with a load to GND. Capacitor 161 161 decouples the
deflection +12 volt supply by the LM324 165165 . Components G4 G4 , G5 , 178178 , 201 , and 203
203 are
used to correct a slight nonlinearity in the vertical deflection yoke via the vertical control circuit.
The diode modulator (DM) incorporates diode 311311 to control the voltage on the DM main node
(cathode of 311 ) during the flyback pulse time. If the diode 311311has low forward current, the DM
node voltage will be high during flyback time and the horizontal size will be small. The forward
current in the diode 311 311 comes from the current buildup in inductor 316 316 during flyback time and the
voltage across the capacitor 315 315 during trace time. If the voltage is large across the capacitor 315 315
during trace time, most of the inductor current is discharged before the next retrace cycle and the
horizontal size is small. This condition can be checked by connecting a DVM to the vertical heat sink
(GND) and to the heat sink 186 186 (collector 185185 ). The voltage for minimum horizontal size is about 22V.
Capacitor 315 315 supplies a voltage for the inductor 316 316to work against similar to the 1,000uF
capacitor 195 195 in the vertical yoke circuit. For max. horizontal size, the voltage across 3 15 315 is about 8V,
and the diode 311 311 , current before retrace is high Diodes 3 08 308 and 3 10
310 clamp the DM node to GND
to keep the yoke current stable during trace time. Inductor 3 01 301 is an additional width coil and 3 02 302
is a horizontal linearity coil. Capacitor 300300 and resistors 298 298 keep the coils from ringing after
retrace. Capacitors 306 306 and 307307 form the normal Cp. The raster may be shifted by making solder
connections: left HL HL or right HRHRwith increased effect Z Z . These solder connections introduces a DC
current in the horizontal yoke via diode 193293 or diode 312 31 . Resistor 303303 limits
41
the maximum current and resistor 309309permits fine adjustment.
 HORIZONTAL RASTER WIDTH and POSITION CONTROL SCHEMATIC

+12V
VERTICAL + HORIZONTAL
CONTROL SIZE 10K
RC5
VERTICAL 481 GND
VERTICAL OUTPUT
LINEARITY - VERTICAL Remote Control
YOKE PCB 490
127VDC
H. RAS POS. CONTROL
1,000uF FR205 HORIZONTAL RASTER ADJ.
+127V FR205
195 FBT Pin 9

293 HR HL Z 312
3.3ý 314
193 470ý,1/2W 270ý, 2W BEAM
GND CURRENT
12K, 2W 309 303 FBT Pin 4
+12V 289 HORIZONTAL
36K 10uF 1K 4 HORIZONTAL YOKE OUTPUT
+ 10K 433 FBT Pin 10
203 201 178
.33uF G3 7.15K
183 127VDC YC4
10K 127VDC
10 9 172 50V
150V 170V
300V
Pincushion correction. 184 1/4 8 YC3 MAX.
MAX. MIN.
MIN. H. Size
LM324
10K 7 5 + 10
G7 1/4 7 6VDC H.
LM324 4V 17mS 6VDC WIDTH 2.2K
1/2W 1N4005
6 6 3V 17mS 2092
165 68uH 220uH 298
220K 301 301 308
10K 9 5K 8
G6
8 5 G4 G5 .01uF
3,300pF 1.5KV
+6V LINE
H. LIN. 300 306
19
2092 12K Horizontal 2092 8.87K 68uH 2092
36K
166 Pincushion
22K 8.2nF
3.3K 166 167 302
1.82K Parabolic 167 306
Linear .47uF 1N4005
179 G17
20 250V
2.2K 28K Blooming correction. 8VDC 23V 305 310
70V 250V 63uS 2092
159 +6V G12 Width MAX. MIN. H. Size
+ 100uF .33uF
.047uF .01uF 100K Adj. 50K 305
162 169 163 G10 166A G9

8VDC 22V
38.3K 4V 12Vp-p 17mS 750uH
H SIZE 1 13
MAX. MIN. H. Size
+12V 316
G11 44.2K
4
* 14 0ý
10K 12 + G13 2SC2344 1N4937
2 4 1/4
G2 164 14 2.2K 278
1/4 1 LM324 311 .022uF
LM324 6.8K 13 G14 HEAT
3 +6V 19 2.7uF 630V
3 185 SINK
G16 15 16 315 307
11 186
6.8K 18 16K 17 .01uF
10K 171
.1uF
G1 161 G15 168
2, 12 GND GND

42
 SIMPLIFIED POWER SUPPLY CIRCUIT FUNCTION DESCRIPTION
+127V LOAD
FLYBACK
DIODE +
+ Res.
H Dy & EHT
AC GND 266 VIDEO
line GND

+
Error Amp. C5184 FET SECONDARIES
User supplied
Comp.
Isolation
DRIVER 258
Transformer
268
V REF. OSC. ENABLE
280
V- (-200V) V- 292

The switching regulator includes the power FET 268268which passes current from
V- to GND through the inductor 258258. During the time the FET is on, the current in

the inductor is increasing and the inductor is storing energy. When the FET
is turned off, the stored energy in the inductor continues supplying current to GND.
But in this case, the current path is from V+ to GND, instead of V-to GND.
During this part of the cycle, the current in the inductor is decreasing.

FET drain voltage

Current in inductor Current supplying GND

Voltage across 292 Current from V-

Current in diode 266 Current added to the +127V line

Flyback pulse

As can be seen from the waveforms, the largest number of changes occur when
the FET is turned off. Also, the FET drain voltage switches fast due to the high
inductor current. To minimize video interference from the power supply, the
power supply is synchronized to the horizontal oscillator such that horizontal
blanking is coincident with the FET turn off time.
The C5184 280280 is the series regulator IC. All of the control circuits that are built
into this IC work together to produce one output signal, which is the FET drive
signal. This signal can take on many shapes depending on the load conditions
of the power supply. The waveforms for normal operation are shown above.
For the shorted +127V to GND condition, which also occur right on power up,
The waveforms are:
FET Gate Drive

FET Drain Voltage

Inductor Current

The first FET pulse is a full on pulse which causes current to flow in the inductor.
After the FET is turned off the current in the inductor drops much more slowly than
normal since the inductor is discharging into a much lower than normal voltage.
If the FET were turned on for full power in the next cycle with current still flowing
in the flyback diode, a current spike of 6A would occur, which is a power spike of
2,000W. The reason for this is that the diode stores charge when current flows
which turns into reverse current for a short time when the voltage is reversed
across the diode. 43
 SIMPLIFIED POWER SUPPLY CIRCUIT DESCRIPTION
The FET drive waveform avoids this problem by sensing flyback diode conduction.
If the flyback diode conduction is sensed, the low current start mode is selected.
this mode turns the FET on, to a current of .1A, for not more than 4uS. If before or
during the low current FET on time, the flyback diode breaks free, and the FET
drain voltage goes down, the flyback diode voltage comparator will signal the
regulator to permit the FET to be turned on for a full power cycle.
The cycle after the last low power cycle in the waveform above is an example of this
condition. The flyback diode voltage comparator inputs are located at pins 12 & 13
of the C5184. The two resistor dividers J10 J10 ,J11J11and J12J12 ,271
271connect the
comparator across the flyback diode. The comparator enables the FET drive only
after a 10% voltage drop is measured across this diode.
Another fault condition exists when the FET exceeds 1.6A drain current.
This condition can occur if the oscillator frequency is too low, the FET drain is shorted
to GND or V+, the transformer has a shorted secondary, or the core is broken.
In these cases the voltage across the FET source resistor 292 292 exceeds 1.6V which
is sensed by the over current comparator at pin 11. If pin 11 exceeds 1.6V, the FET
drive is set to 0V for the rest of the cycle. In some cases, this condition can
produce an output waveform which looks normal, but the voltage across the load
(+127V to GND) would be low or unstable. A quick check for this condition is to
check the peak voltage across the FET source resistor. CAUTION; Whenever
connecting a scope ground to V-, be sure that the other scope probe or common
grounded devices are not connected to the monitor GND.
Most of the power supply fault conditions cause the power supply to chirp
because the source of +17V for the regulator IC is generated by the power supply.
A special circuit is built into the regulator IC, which permits charging the +17V line
filter capacitor with only a very low load from the IC. This circuit turns the rest
of the IC on only after the voltage at pin 15 reaches 17V. If the transformer does not
supply at least 12V to this line before the filter capacitor discharges to 12V, the
regulator IC turns off. The reason for the audible chirp, is that, the power supply
is not full on for each cycle which produces a frequency low enough to hear.
A 19V to 20V @ 1A, DC, isolated power supply is a tool necessary for trouble shooting
CERONIX monitors. When trouble shooting the power supply, it can be connected to
V- and the +17V line to keep the power supply running while checking the voltages
and waveforms to find the fault. It can also be used to supply the GND to +24V line
for checking the horizontal circuit. If the horizontal circuit does not work, the
power supply will chirp. Without the horizontal circuit working, there is not
enough load on the power supply for transformer action to keep the regulator IC
+17V line up to the minimum of +12V. A quick check for this condition is to clip
a 2-4K@10W power resistor from GND to +127V line. If the chirping stops, the
horizontal is probably not working.
The heart of the power supply is the oscillator which supplies the basic timing.
The FET drive is always low during the negative slope of the oscillator or, when
synchronized, after the start of the sync pulse. The low to high transition of the
FET drive, pin 10, is determined by the voltage at the output of the error amplifier.
If the 127V line goes up in voltage, the error amplifier voltage goes up, which then
intersects the oscillator waveform at a higher voltage and causes the FET on time to
start later and be shorter. This negative feedback accomplishes the control loop of
the power supply.
The regulator IC has a built in reference voltage which is used by the
error amplifier set and hold the +127V line constant. Solder connections on the J PRA
are used to adjust the +127V line in steps of ±1.5V.
The over voltage protect circuit, when activated, turns off the regulator IC until
power is disconnected. This circuit is connected to the rectified flyback pulse, which
outputs a voltage that is proportional to the EHT. The circuit's main purpose
is to protect the user against excessive x-ray which is caused by excessive EHT. 44
 SWITCH MODE POWER SUPPLY CIRCUIT DESCRIPTION
127V
The series regulator IC 280280, controls current to the monitor GND by pulse width modulation.
A PNP transistor 250250, has an emitter current, that is directly proportional to the 127V line voltage
due to resistor J1J1 and adjustment resistors J13J13& J14 J14. This current is transmitted to the power
supply V- line, and is applied to a resistor J5 J5, J15 J15
, & J16 J16
. The voltage across these resistors
is compared to a reference voltage by the error amplifier. If the +127V line goes up the output of
the error amplifier voltage goes up. The pulse width modulation, which controls the + 127V line
voltage, is accomplished by turning the FET drive on at some particular voltage along the rising
slope of the oscillator waveform. This particular voltage is the error amplifier output voltage.
Oscillator waveform without sync:

Oscillator waveform with sync: Error Amp. V.

FET drive, C5184 pin 10: Fet Drive

With Sync
The FET drive is always off during the negative slope of the oscillator, or just after the sync pulse.
Since the FET drive pulse is started by the error amplifier voltage and terminated by the end of the
oscillator cycle, a control system via pulse width modulation has been established. The oscillator
waveform is produced by charging capacitor 277 277 with a constant current set by resistor J7 J7
to a voltage of 5V and then discharging the capacitor with double the charging current to 2.5V.
Adding the flyback pulse, via capacitor 288288to this waveform synchronizes the oscillator, since the
oscillator frequency is set below the horizontal frequency.
Resistors J2 J2 , J4 J4 and capacitor 274 274 limit the error amplifier's AC gain, to hold the control loop
stable. Capacitor 275 275 holds the error amplifier stable. Capacitor 281 281 reduces power supply
noise, but, if too large, will cause the power supply to be unstable.
FR205
The 127V line is adjusted by making solder connections on the J PRA
(refer to page 56 for the layout). Solder connections AA and B Bare used to 2,200pF
252
raise the 127V line up to 4.5 volts in steps of 1.5 volts. Connections
220Vo
C and D
C D lower the 127V line as much as 4.5V. The 127V line 252A
should be adjusted if below 125.8V or higher than 128.2V.
246 253
Resistors 273 and 249 are used for monitors with special + 100K
127V line voltages. 150uF 1/2W
CUT
256 247
The FET 268 268 works together with the transformer 258258 FOR
220Vo 250V 8,14
to provide a low resistance current path from V- to GND. INRUSH 7
This low resistance coupled with no large voltage times CURRENT 2,200pF +150uF
LIMIT 90K
current products is what makes the power supply efficient. 257
Resistor 292 provides a means for sensing the FET current. 25-.5ý 254A J6
250V
In the low current mode, it is used to set the 100mA current GL200 FR205
240 +
and in the full on mode it is used to sense the max. current. 100uF
254
Resistors 264 , 270 270 and capacitor 265 265 reduce power supply 286
220Vo V-
electrical noise. Transistor 284 284 and diode 283 283 short the 3A FUSE
FET drive to V- when the monitor is turned off to protect the 245 255
FET from conducting current with a still large drain voltage.
Resistors J10 J10 , J11 J11 , J12 and 271 271 provide a means for
checking flyback diode 266 266 conduction via a comparator.
To deguassing coil
and posistor.
If the comparator measures low flyback diode voltage the 241
FET is turned on to the .1A low current mode. This mode PC 115VAC PC
2 INPUT 1 238
is necessary during power up, since initially the +127V line
is 0V and no reverse diode voltage exists. The over voltage protect circuit has a trip voltage of 8V
and when it is activated, it shuts down the power supply. The EHT is measured by rectifying the
flyback pulse, with diode 290 290 , from a secondary winding of the FBT. Capacitors , 285 285
291 291 and
resistors 287 , J9 J9 are connected as a low pass filter to smooth out the simulated EHT voltage which
is then applied to the C5184 at pin 14. Resistor J8J8protects the IC current sense input from voltage
spikes and resistor 251 251 protects the PNP transistor from momentary overvoltage damage due to
line spikes. Zener diode 295 295 protects the horizontal and video circuits
from overvoltage due to power supply failure. If the +127V line exceeds 160V,
45
the zener diode 295 295 shorts to GND the +127V line.
 SWITCH MODE POWER SUPPLY SCHEMATIC
127V +24V +16V +127V
+127V
C -1.5V D -3V
+27V FR205
20
2.33K 4.67K .1uF FR205
150uF 263 +16V
TZ160B-T3 250V 250V
193K J13 J14
160V 317 294 + 1,000uF .1uF + 1,000uF .1uF 260
J1
295 215 262 131 261
1 2SA1371E
100K GND GND
*
249 251
17V 250 16.3-17.8VDC
SMXFR 5 FROM
1 +15V 16
6 6.5-7.5VDC 14.8-16.3VDC 9 FBT
INPUT 18ý FR205 4
10.6K .01uF +17V 15 3
FR205
ERROR INPUT 248A 258
J5 275
281 248 266
AMP. 1 2
B
260ý 6.5-7.5VDC 2
+3V
J16 INPUT Over
A 56K 191K 1N4148
.5-.8VDC 3 Voltage 14
COMP. Protect }
6-7VDC
130ý J4
+1.5V 4 +127V 16 287 1,000
J15 6,800pF 56pF INPUT .1uF 290
.022uF 38.3K pF
274 275
275 285
5 296 291
11K 4 V- J9
3.4-4.2VDC
Output
J2 20
3.6-4.4VDC
23.2K CONTROL & 6V 63uS 1.00M 1.00M
2
FAULT SENSE
J3 56pF 12 J10 271
.1-.5VDC 5 4uS
COMP. 17 18
1.87K DELAY + 13 5.3-5.7VDC
273 276
9 14.7K 15.8K
.10-.17VDC
33.2K 5.7-6.3VDC 6 Rx OUTPUT
1V 63uS J11 J12

J7 11 12 510ý
Osc. Current
3.5-4.1VDC 13
SENSE 2.4-3.6VDC J8
3-4V 63uS
6,800pF 14V 63uS 2SK1446
7 Cx 18ý
Heat
330pF DRIVE
10 Sink
277 267
288 270
8 +7.5V REF. V- 9 1N4005 268
MPSA64 200pF
283
XRC5184 280 265
0VDC D 284
48V 63uS 1.2ý 150ý
FROM 2,200pF
FBT 292 264
V- J PRA PINS: 3,10,15, & 19 282 V-

POWER VOLTAGE CURRENT CIRCUIT SUPPLIED DIODE FILTER CAP. NOISE CAP.
SUPPLY 17VDC 7mA POWER SUPPLY CONTROL 248 100uF 286 NONE
LOW VOLTAGE 16VDC 250mA VIDEO AND INPUT 260 1,000uF 131 .1uF 261
SECONDARIES 27VDC 250mA V. &H. DEFLECTION 263 1,000uF 215 .1uF 262

At the input to the power supply is a voltage doubler which outputs between 240 to 425VDC
depending on the AC line voltage. It has a three amp fuse 245245to protect the PCB traces, an inrush
current limiter 240
240to protect the rectifier diodes 252 252
, 254 254
, and optional capacitor 241 and
241
inductor 246 which can be used to reduce conducted noise from the monitor AC input. For 220VAC
operation the voltage doubler is replaced by a full wave rectifier by adding diodes 253 253, 255 255
and
cutting the 220Vo trace. 256256 & 257 257 are the raw DC filter capacitors. Resistor J6 J6 supplies the
power supply start current and resistor 247247balances the series connected filter
capacitors for 220VAC operation. 46
 Equipment setup for repairing the Model 1492 Monitor

VARIABLE

+127.0 ISOLATION
DVM
TRANSFORMER

OSCILLOSCOPE
TRANSFORMER

115
VAC
ISOLATED
+20V @.5A DC
POWER
SUPPLY

CERONIX Model 1492

ISOLATED +20V POWER SUPPLY CIRCUIT.

1N4005 1A Std. Fuse

+20V
1A Std. Fuse

1N4005 4.75K,1% 20 Volt

Power SW @.5 A
1,000uF
115 VAC 47K 10K
20V @ 1A 35V 1uF
60 Hz Transformer 1N4005
1N4749A
Triad #F-254 X
301R,1% 24V Zener
1N4005 ADJ.
-7V 0V
IN OUT
LM337MT
HEAT SINK

47
 Problem Solving Tools
SAFETY FIRST; Use only one hand when working on a powered up monitor to avoid electrical
shock. Always wear safety glasses.
Many of the failures that cause burnt components and boards are eliminated by the load sensitive
switching mode power supply in the CERONIX monitor. This feature can cause problems with
servicing the monitor if the proper trouble shooting approach is not used. The equipment setup,
shown here, is necessary for efficient trouble shooting of the CERONIX monitors.
Problems that cause the power supply to chirp are:
1. Insufficient +127V line load.
2. Overloaded +127V, +24V, or +16V lines.
3. Shorted +127V, +24V, or +16V lines.
4. Power supply component failure.
5. Raw DC (+127V to V-) voltage too low.
1. A quick check for the insufficient +127V load is to connect a 2K to 4K ohm 10 watt power
resistor to GND and the +127V line. If the chirping stops, proceed to check the horizontal
deflection circuit. First disconnect the board from the AC supply. Then connect the +20V supply,
0V line to GND, and the +20V line to +127V and +24V lines on the monitor. Now the complete
horizontal and vertical circuits can be checked with the oscilloscope and DVM.
The flyback waveform will be about 140Vp–p instead of 1,000Vp–p which permits checking even
the horizontal output transistor, collector, waveform.
2. For the overloaded supply line problems, which often occur only when the +127V line is fully
powered up, the +20 volt external power supply is used to keep the monitor power supply running.
To use the external supply, connect the 0V line to V- (anode of diode 254254) and the +20V line to
the monitor power supply +17V line (cathode of diode 248248).
Connect the oscilloscope GND to V- and the probe to the FET drive (anode of diode 283283).
TAKE CARE NOT TO TOUCH THE OSCILLOSCOPE AND MONITOR CHASSIS DURING THIS
TEST, SINCE
THE VOLTAGE DIFFERENCE CAN BE AS HIGH AS 400 VOLTS.
Increase the AC supply, slowly, to the normal operating voltage while monitoring the +127V line
to GND voltage with the DVM. The power supply overload condition can be seen on the scope
as an almost square wave which can break up into short and long pulses as the AC line voltage
is increased. The short pulses are the flyback diode current sense pulses. Sometimes the monitor
will operate normally in this mode, in which case, watch for smoke and after a few minutes of
operation disconnect the power connections and carefully feel around the conductor side of the
board for hot spots. Overload conditions will not harm the power supply unless there is a problem
in the power supply.
3. If the +127V crowbar zener 295 295 is shorted, a fault exists in the power supply which
permitted the +127V line to exceed +160V. First replace the zener. Never operate the monitor
without the crowbar zener installed. Then with the external supply, the DVM, and the scope
connected to the power supply (as in 2) slowly increase the AC line and observe the power supply
response. Do not exceed +145V on the +127 V line. If the monitor runs normally, a fault may
still exist in the power supply power down circuit. Check parts 283 283 and 284 .284
If the crowbar
zener is shorted and the FET is internally shorted, the C5184 IC 280 280 should also be replaced.
If there is no FET drive waveform, check the voltages and waveforms on the C5184 pins
and compare them to the voltages and waveforms on the schematic.
Shorts on the +127V, 24V, and 16V lines other than the crowbar zener are not likely to be
connected to the power supply even though the power supply chirps. By operating the power
supply with the +20V external power supply many of these problems can be found using the same
procedure as are used in trouble shooting monitors with linear power supplies.

4. The power supply may chirp if: The transformer core is broken or a winding is shorted.
The 1.2 ohm current sensing resistor value is too high.
The +17V line is open. (goes away when ext. PS is used)
5. There is a line voltage range of about 60% to 70% AC line voltage where a correctly
operating monitor will chirp. 48
 SETUP AND CONVERGENCE PROCEDURE
1. Use a knife to brake free the magnetic rings on the yoke which are locked
with red varnish. Bring the adjustment tabs on each pair of magnetic rings
in line for the starting point.

2. Loosen the yoke clamp. Remove the yoke wedges and the tape from the CRT.

3. Connect a test generator to the video input and clip the red lead to the
+12V line (anode of diode 101
101 ).

4. Turn the monitor on. Switch the test generator to red field.
Adjust the horizontal and vertical raster size, on the remote control board,
for under scan. Let the monitor run for at least half an hour.

5. Check the auto bright control voltage with a DVM connected to GND and pin 8
of the LM324 146 146 . The voltage range is 4.3V to 4.9V. If out of range,
adjust this voltage to 4.6V by using pliers to rotate the bottom knob on the FBT.

6. Degauss the picture tube and front part of the frame.

CAUTION: To avoid electrical shock , take care not to touch the yoke conductors
or push against the anode cap. Always keep one hand away from unit.

7. Adjust the yoke position, on the CRT neck, to the center of purity. One way to
locate this yoke position is to make a felt pen mark on the CRT neck at the
rear extreme of purity and another mark at the front extreme of purity.
Make a third mark between the two marks and set the yoke to this position.
Rotate the yoke to line up, the raster top line, with the top of the picture tube.
Tighten the yoke clamp. Tilt the yoke side to side and up and down while
watching the red field to verify that purity is good.

8. On the 13 inch CRT, use the purity magnets (closest to the yoke coils) to center
the raster horizontally. To accomplish this, find the rotational position
where spreading the tabs has the most effect on the horizontal position
and spread the tabs a minimum to center the raster horizontally. On the 20 inch
CRT, the purity magnets are often needed to optimize purity. The horizontal
raster position solder connections are used to adjust the raster position.
These solder connections are located on the foil side of the PCB next to the FBT.
Connection HR shifts the raster right, HL shifts the raster left and the range of this
shift can be increased by making solder connection Z Zunder resistor 309309 .

9. Check the purity with red field and with blue field while tilting the yoke side
to side and up and down.

10. Switch the generator to red/blue grid. Adjust the 4 pole magnets (center pair)
for convergence of the red and blue guns in the center of the screen.

11. Tilt the yoke up and down for the best convergence around the edge of the grid.
Insert the top yoke wedge. Tilt the yoke side to side for the best
convergence around the edge of the grid and insert the rest of the yoke wedges.
Secure the wedges with tape.

12. Switch the generator to white grid. Adjust the 6 pole magnets (Pair closest
to the socket board) for convergence of the green gun.
Step #10 and this step may have to be repeated for optimum convergence.
49
 1492 & 2092 VIDEO INTERFACE PROGRAMS

N K H
AC Coin & Slot Service; (1492)
Q
X 4 Solder Connections: Q, X, Y, & S.
I Y G
L B Standard Board.
O J M T U
R E S

FC D A
P
AA

N K H
Advanced Touch Systems; (1492)
Q Change 007 , 024 , & 037 from 340ý to 205ý ±1%
X
I Y G Change 008 , 023 , & 034 from 12.1K to 7.15K ±1%,
L B
O J M T U 12 Solder Connections: A, B, C, G, H, I, J, K, L, P, T, & Y.
R E S

FC D A
P
AA

N K H
Aeries International; (1492)
Q
X 11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.
I Y G
B Standard Board.
L
O J M T U
R E S

FC D A
P
AA

N K H
Altec; (1492)
Q
X
11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.
I Y G
L B Standard Board.
O J M T U HFo = 15,370 ±200Hz.
R E S

FC D A
P
AA

NOTE: Solder connections S, T, & U, and resistor 094

set the video gain and may change due to
component variations. 50
 1492 & 2092 VIDEO INTERFACE PROGRAMS

N K H Aristocrat; (1492)
Install three 100pF disc capacitors at 010 , 022 , & 041 .
Q Invert horizontal sync by adding a solder connection
X on the "I" PRA above pin 5.
I Y G
B
B Install posistor at 244 .
L
O J M T U
R E S
S 11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.
Before final test, clip out 045 , 270 ohm resistor, and add
D A
A one solder connection AA by component no. 060 .
FC
P
High resolution board.
AA

N K H Automation; (1492)
Q Change 002 From 75ý to 130ý..
X
I Y G Change 027 From 75ý to 47ý.
L B
B Change 094 from 2.7K to 10K.
O J M T U
R E S
S Install posistor 244 .

11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y

FC D A
A
P Before final test add solder connections B & C.
AA High resolution board.

N K H
Bally; (1492)
Q
X
I Y G 12 Solder Connections: D, E, F, G, H, I, J, K, L, P, T, & Y.
L B
O J M T U Add a solder connection on the "I" PRA above pin 5.
R E S
Install posistor at 244 .

FC D A High resolution board.

P
AA

H
Brunswick; (1492)
N K
Change 007 , 024 , & 037 from 340ý to 301ý ±1%
Q Change 235 , from Hfo set resistor to 3K pot.
X
Y Remove the 2.7K resistor at 094 .
I G
L B Add a solder connection on the I PRA above pin 5.
O J M T U
R E S 11 Solder Connections: A, B, C, G, H, I, J, K, L, P, & Y.
Before final test, add the AA solder connection and
FC D A cut out the 270ý resistor at 045 .
P
Standard board.
AA

NOTE: Solder connections S, T, & U, and resistor 094

set the video gain and may change due to
component variations. 51
 1492 & 2092 VIDEO INTERFACE PROGRAMS
By Video; (2092)
N K H Change 008 , 023 , & 034 from 12.1K to 2.67K,1%
Change 002 , 005 , & 027 from 75ý to 2.7K, 5%, 1/4W
Q Change 203 from 36K, 5% to 24.3K, 1%.
X
Y Install posistor at 244 .
I G
L B
12 Solder Connections: A, B, C, G, H, I, M, N, O, P, T, & Y.
O J M T U
R E S Before final test, clip out 045 , 270 ohm resistor,
and add one solder connection AA by 060 .
FC D A
P For the 13" CRT monitor, Add solder connection
AA S, and omit T . do not change resistor 203

N K H

Q
Carson Valley Inn; (1492)
X
I Y G Change 200 from 127K to a 200K pot.
L B
O J M T U 4 Solder Connections: Q, X, Y, & S.
R E S
High resolution board.

FC D A
P
AA
12 Solder Connections: Q, X, Y, & S.

N K H
CAS Ltd.; (1492)
Q
X
Y G Add a solder connection on the I PRA above pin 5.
I
L B Change 094 from 2.7K to 10K.
O J M T U
R E S
11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.

D A Standard board.
FC
P
AA

N K H

Q
CEI; (1492)
X
I Y G Change 094 from 2.7K to 10K.
L B
O J M T U Install the posistor at 244 .
R E S
11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.

FC D A
P
AA

NOTE: Solder connections S, T, & U, and resistor 094

set the video gain and may change due to
component variations. 52
 1492 & 2092 VIDEO INTERFACE PROGRAMS

N K H

Q
Games of Nevada; (1492)
X
I Y G 12 Solder connections: D, E, F, G, H, I, J, K, L, P, T, & Y.
L B
O J M T U High resolution board.
R E S

FC D A
P
AA

N K H
IGT; (1492)
Q
X
Y Delete degaussing circuit.
I G
L B 4 Solder Connections: Q, S, X, & Y.
O J M T U
R E S High resolution board.

FC D A
P
AA

N K H
Keevex; (1492)
Q
X
Y Install posistor at 244 .
I G
L B 4 Solder Connections: Q, S, X, & Y.
O J M T U
R E S Horizontal frequency is 17,182Hz

High resolution board.

FC D A
P
AA

N K H
Mast Keystone; (1492)
Q
X
Change 002 , 005 , & 027 from 75ý to 1K ±5%.
I Y G
L B
O J M T U 5 Solder Connections: A, B, C, P, & S.
R E S Standard Board.

FC D A
P
AA

NOTE: Solder connections S, T, & U, and resistor 094

set the video gain and may change due to
component variations. 53
 1492 & 2092 VIDEO INTERFACE PROGRAMS

N K H
RS 170; (1492)
Q Change 007 , 024 , & 037 from 340 ohm to 140 ohm ±1%.
X
I Y G Change 008 , 023 , & 034 from 12.1K to 3.32K ±1%.
L B Remove 045 , 046 , 047 , & 048 .
O J M T U
R E S Add a 2.2K resistor to hole by video connector 006 pin 5 and
hole between resistors 050 & 051 .

FC D A 12 Solder Connections: A, AA, B, C, G, H, I, J, K, L, P, & Y.

P
AA

N K H Semi-Conductor; (1492)
Q Change 002 , 005 , & 027 from 75ý to 27ý ±1%.
X
Y Change 007 , 024 , & 037 from 340ý to 140ý ±1%.
I G
L B Change 008 , 023 , & 034 from 12.1K to 3.32K ±1%.
O J M T U Change 064 from 2.7K to 10K ±5%.
R E S
Install posistor at 244 .

FC D A 11 Solder Connections: A, B, C, G, H, I, J, K, L, P, & Y.

P
High resolution board.
AA

N K H
Syntec; (2092)
Q
X Change 203 from a 36K ±5% to a 24.3K ±1% resistor.
I Y G
B Change 094 from 2.7K to 10K ±5%.
L
O J M T U Delete degaussing circuit.
R E S
5 Solder Connections: Q, U, R, X, & Y.
FC D A
P
AA

N K H

Q
United Tote; (1492)
X
I Y G
B Change 002 , 005 , & 027 from 75ý to 1K ±5%.
L
O J M T U Change 008 , 023 , & 034 from 12.1K to 4.42K ±1%.
R E S
12 Solder Connections: A, B, C, G, H, I, M, N, O, P, U, & Y.
FC D A
P
AA

NOTE: Solder connections S, T, & U, and resistor 094

set the video gain and may change due to
component variations. 54
 1492 & 2092 VIDEO INTERFACE PROGRAMS

N K H
Western Amusement (1492)
Q
X Change 094 from 2.7K to 10K, ±5%.
I Y G Install posistor 244 .
L B
O J M T U 11 Solder Connections: D, E, F, G, H, I, M, N, O, P, & Y.
R E S
Standard board.

FC D A
P
AA

N K H
4 Line TTL; (1492)
Q
X
Change 002 , 005 , & 027 from 75ý to 1K ±5%.
I Y G
L B Change, the video input connector, 006 from a 6 conductor
O J M T U to a 7 conductor header.
R E S
5 Solder Connections: A, B, C, P, & S
FC D A
P
AA

N K H

Q
X Solder Connections:
I Y G
L B
O J M T U
R E S

FC D A
P
AA

N K H

Q
X Solder Connections:
I Y G
L B
O J M T U
R E S

FC D A
P
AA

NOTE: Solder connections S, T, & U, and resistor 094

set the video gain and may change due to
component variations. 55
NOTES:

56
 1.2K 790ý
3.78K
B9 B19
B4 1490-91

7 6 5 4 3 2 1 40.2K
1.65K B17
836ý
1.27
NE592 K B11 B10
B8
5.62K
B12
8 9 10 1 12 13 14

68K 606ý
B1 B6 539ý 3.32
K 270ý
B20 B18
27ý 1490-91
270 66ý 510ý
B7
ý
180 B15
ý 392ý 32ý
B3 B5 B14
B2 B13 B16

1 2 3 4 5 6 7 8 9 10 1 12 13 14 15 16 17 18 19 20
PNP
drive NPN 7.9V NPN NE592
GND +12V VIDEO
GND AUTO
GND 127V 7.9V PNP E PNP B PNP PNP PNP AMP
cap. E LINE B Output LINE INPUT BIAS LINE CAP. DIODE B E C Output

B
P/N CPR0500

VIDEO AMPLIFIER RESISTOR ARRAY "B"

200ý 200ý
C16 C13
200ý
C8 4K 4K 4K

5.00K 5.00K
20K 1.82 2.74K 1.82
C10 C11 C14 5.00K
68.1K 68.1K 68.1K
K K C9 C12 C15
C1 C2 C3 C5
C6 C7 C4

1 2 3 4 5 6 7 8 9 10 1 12 13 14 15 16 17 18 19 20
Program H. Program BLUE GREEN Program RED 10.7V 4.2V RED RED RED GREEN GREEN GREEN BLUE BLUE BLUE
PULSE Blank PULSE i Beam i Beam PULSE i Beam GND NC LINE LINE Amp out Amp FB i sense i sense Amp FB Amp out i sense Amp FB Amp out
4 5 7 6 LM324 Pin No. 2 1 13 14

AUTO BIAS RESISTOR ARRAY "C" C

P/N CPR0503

Solder connection A reduces the horizontal raster size.

38.3K
G11
10K
28K
10K G3 G12
50K
220K G9 2.2K
G6 G4
1.82
A 44.2K K
16K 6.8K
10K 10K 5K G17
G1 G2 10K 10K 100K G13 G14 G15 G16
G7 G5 G8 G10

1 2 3 4 5 6 7 8 9 10 1 12 13 14 15 16 17 18 19 20
Pincush. LIN. DM
H. SIZE +6V +12V Couple to Pin. V. LIN.
buffer NC GND DM control DM amp NPN Stability DM amp +6V i Beam
POT GND Source LINE Cap. Buffer Correct. node Buffer V FB Output B Cap. Neg FB LINE FB
3 7 5 8 9 12 14 LM324 Pin No. 13 1

P/N CPR0504 G
HORIZONTAL WIDTH CONTROL RESISTOR ARRAY "G"
57