Zenith ZCM-1490 User manual

SERVICE MANUAL
Color Video Monitor
ZCM-1490
;TI'NI'H I data .
systems
585-230 860-183

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in this manual. When a service bulletin is received, mark the manual and list
the information
in the record below.
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.-
-
UMITED RIGHTS LEGEND
Contractor is Zenith Data Systems Corporation of St. Joseph, Michigan 49085. The entire
document
is subject to Limited Rights data provisions.
Copyright 1988 by Zenith Data Systems Corporation
Printed in the United States of America
Zenith
Data Systems Corporation
St Joseph, Michigan 49085
INITIALS

Warnings and Cautions
WARNING
Removing or lifting the ground from the AC power
source may present a potentially lethal shock hazard.
Do not use an AC two-to-three wire adapter plug with
this unit.
WARNING
The CRT anode retains a potentially lethal voltage
even when the monitor
is turned off. Perform repairs
only after the CRT anode has been properly dis-
charged. Refer to Figure
6-1 and the following proce-
dure to discharge the CRT anode:
1. Connect a clip lead or heavy gauge wire to
chassis ground.
2. Connect the other end of the lead to the stem of
a flat-blade screwdriver that has
an insulated
handle.
3. Insert the blade of the screwdriver under the
rubber insulation that covers the anode lead
on
the CRT and make contact with the anode ter-
minal. Depending on the amount of charge pres-
ent on the anode, a distinct snap may be heard
as the CRT discharges.
WARNING
The switch mode power supply contains circuits that
generate dangerous high frequency, high amplitude,
quasi-square wave signals that present a potentially
lethal shock hazard.
In the ZCM-1490, this circuitry is
located on a separate, exposed circuit board located
along the left side of the monitor when viewed from
the back.
Do not attempt to service the power supply.
WARNING
To prevent both personal injury and equipment
damage, always use
an isolation transformer when
troubleshooting this monitor.
CAUTION
Under no circumstances should the original design
be modified or altered without permission from Zenith
Electronics Corporation. All components should
be
replaced only with types identical to those in the
original circuit, and their physical location, wiring, and
lead dress must conform to the original layout upon
completion of repairs.
CAUTION
Some components contain an X in their reference
number. For safety reasons, these components must
be replaced only with identical components.

Contents
Chapter 1- Introduction Chapter 5 - Circuit Descriptions
Specifications
............................ 1-1
Functional Overview ........................ 5-1
Video Input Processing ..................... 5-3
Chapter 2 - Installation Video Amplifiers
........................... 5-3
Controls and Connections
................... 2-1 Video Drivers ......................... 5-4
Set-Up and Operation
...................... 2-3 Cascode Output Amplifier ............... 5-4 .
Initial Tests
............................... 2-3
DC Restoration ....................... 5-4
Color Bar Test
........................ 2-3 Class AB Output Stage
................. 5-5
Fill Screen Test
....................... 2-3 Cutoff
............................... 5-5
Retrace Line Prevention
................ 5-5
Chapter 3 - Disassembly Black Level
.......................... 5-5
Rear Cover Removal
....................... 3-2 Sync Input Processing
...................... 5-5
Rear Chassis Panel Removal
................ 3-2 Mode Selection
....................... 5-5
Video Board Removal
...................... 3-3 Vertical Processing and Controls
.......... 5-6
Control Board Removal
..................... 3-4 Horizontal Controls
.................... 5-6
PIN Board Removal. ....................... 3-4 Horizontal Deflection
....................... 5-7
Fan and Bottom Panel Removal
.............. 3-5 Horizontal Driver
...................... 5-7
Support Bracket and Shield Removal
.......... 3-5 Horizontal Output ...................... 5-7
Deflection Board Assembly Removal
.......... 3-6 Horizontal Centering
................... 5-8
Deflection Board Removal.
.................. 3-7 Control Grid Voltage
................... 5-8
Power Supply/Dynamic Focus Board Anode Voltage.
........................... 5-8
Assembly Removal
...... ; ............. 3-8 Anode Voltage Regulator ................... 5-8
Power Supply and Dynamic Focus Board High Voltage Shutdown
..................... 5-8
Removal.
............................ 3-9 Automatic Brightness Limiter ................. 5-8
CRT Lead Dress and Removal
.............. 3-10 Vertical Deflection ......................... 5-9
Vertical Centering
......................... 5-9
Chapter 4 - Adjustments Blanking Pulses
.......................... 5-10
Preparation . . .
........................... 4-5 Pincushion Correction
..................... 5-1 a
Deflection Board Adjustments ................ 4-5 East-West Waveform Generator
......... 5-10
Horizontal Hold
....................... 4-5 East-West Regulator
.................. 5-11
Horizontal DC Raster Centering .......... 4-6 North-South Waveform Generator
........ 5-12
Horizontal Phase
...................... 4-6 North-South Output
................... 5-14
Horizontal Size
........................ 4-6 Dynamic Focus
.......................... 5-14
Vertical Hold
......................... 4-6 Degaussing Coil
......................... 5-14
Vertical
DC Raster Centering ............. 4-6
Vertical Size
.......................... 4-6 Chapter 6- Troubleshooting
Vertical Linearity
...................... 4-7 Safety Guidelines
......................... 6-1
Focus ................................... 4-7 AC Leakage Test. ......................... 6-2
Dynamic Focus
........................... 4-7 Suggested Tools and Equipment
............. 6-3
Pincushion Adjustments
.................... 4-8 Inspection and Preparation .................. 6-3
North-South Pincushion
................. 4-8 Color BarTest
........................ 6-4
East-West Pincushion
.................. 4-9 Fill Screen Test . . . . . . . . . . . . . . . . . . . . . . . 6-4
CRT Cutoff
............................... 4-9 Disk-Based Diagnostics
................. 6-4
Video Gain
.............................. 4-10 Cleaning Procedure
........................ 6-4
Final Checks
...... ' ...................... 4-10 Surface Mount Component Replacement
....... 6-5

Troubleshooting Charts ..................... 6-5 5-1. ZCM-1490 Block Diagram
.... , ...... , .. 5-2
Resistance Measurements
................. 6-11
5-2. Video Amplifer Section (Green) ......... ,5-4
5-3. Horizontal Output Amplifier ... , ......... 5-7
Chapter 7- Parts
List
5-4. Blanking Pulse Circuit ................ 5-10
5-5. E-W Waveform Generator
............ 5-10
Chapter 8- Schematics and Waveforms 5-6. E-W Regulator
...................... 5-11
Waveform Explanation ..................... 8-1
5-7. N-S Waveform Generator ............. 5-12
5-8. N-S Output
........................ 5-14
Figures 6-1. CRT Anode Discharging
........... - .... 6-2
6-2.
AC Leakage Voltmeter Circuit ........... 6-3
1-1 . ZCM-1490 Color Video Monitor .......... 1-1
6-3. General Troubleshooting Chart .......... 6-6
6-4. Video Board Troubleshooting Chart
...... 6-7
2-1. ZCM-1490 Front View
................. 2-1
6-5. Deflection Board Troubleshooting Chart ... 6-8
2-2. ZCM-1490 Rear View
................. 2-1
6-6. Pin Board Troubleshooting Chart ........ 6-9
2-3. Subminiature D-type Connector
......... 2-2 6-7. Power Supply Troubleshooting Chart
.... 6-10
3-1. CRT Anode Discharging
............... 3-1
7-1. Exploded View ..................... 7-21
3-2. Rear Cover Removal .................. 3-2
3-3. Rear Chassis Panel Removal
........... 3-2 8-1. Oscilloscope Display Information
........ 8-1
3-4. Video Board Removal ................. 3-3 8-2. Video Board Component View
3-5. Control Board Removal
................ 3-4 .(Component Side)
.................... 8-5
3-6.
PIN Board Removal. .................. 3-4 8-3. Video Board Component View (Foil Side).-.8-6
3-7.
Fan and Bottom Panel Removal ......... 3-5 8-4. Video Board Schematic
................ 8-7
3-8. Support Bracket and Shield Removal
..... 3-5 8-5. Deflection Board Component View
3-9.
D~flection Board Assembly Removal ..... 3-6
3-10. Deflection Board Removal.'
............. 3-7 -(Component Side)
.................... 8-9
8-6. Deflection Board Component View
3-11. Power Supply/Focus Board
(FOil Side) ......................... 8-10
Assembly Removal
................... 3-8 8-7. Horizontal Deflection/High Voltage
3-12. Power Supply and Dynamic Focus Schematic
......................... 8-11
Board Removal ...................... 3-9 8-8. Vertical Deflection/Mode Selection
3-13. CRT Lead Dress and Removal
......... 3-10 Schematic
......................... 8-13
8-9.
PIN Board Component View
4-1. Video Board Adjustment Locations
....... 4-2 (Component Side)
................... 8-15
4-2. Deflection Board Adjustment Locations
... 4-3 8-10.
PIN Board Component View (FOil Side) .. 8~16
4-3. PIN Board Adjustment Locations ........ 4-4 8-11. E-W Generator/Regulator Schematic
.... 8-17
4-4. Dynamic Focus Board Adjustment 8-12. N-S Generator/Output Schematic
....... 8-19
Locations. :
......................... 4-4 8-13. Dynamic Focus Board Component
4-5. Control Board Adjustment Locations
...... 4-5 View
......................... '" .. 8-21
4-6. CRT Gun Waveforms ................. 4-9 8-14. Dynamic Focus Schematic
............ 8-21
8-15. Control Board Schematic ............. 8-21
Page vi
Contents

Tables
2-1. Video Input Cable Pin Functions ......... 2-2
4-1. Monitor Adjustment Devices ............ 4-1
5-1. Mode Selection ...................... 5-6
6-1 . PIN Board Transistor Resistance
Measurements ................... 6-11
6-2. PIN Board IC Resistance Measurements. 6-11
6-3. Video Board Transistor Resistance
Measurements ................... 6-11
6-4. Video Board IC Resistance
Measurements ................... 6-12
Contents
6-5. Deflection Board Transistor Resistance
Measurements ................... 6-12
6-6. Deflection Board IC Resistance
Measurements ................... 6-12
6-7. Dynamic Focus Board Transistor
Resistance Measurements .......... 6-13
6-8. PIN Board TranSistor Voltage
Measurements ................... 6-13
6-9. PIN Board IC Voltage Measurements .... 6-13
6-10. Video Board Transistor Voltage
Measurements ................... 6-13
7-1. Designated Components Parts List. ...... 7-1
7-2. Miscellaneous Parts List .............. 7-18
7-3. Heath Parts List ..................... 7-20
Page vii

The Zenith Data Systems ZCM-1490 is a high-
resolution analog
RGB color video monitor. This
monitor incorporates Zenith's patented flat technol-
ogy CRT. The ZCM-1490 can
be used with a com-
puter video source that supplies
an analog RGB
color signal having a 31.49 kHz horizontal scan fre-
quency.
It can also display information in CGA, EGA,
MDA, and Hercules video modes provided that the
video source supplying the monitor
is capable of
gelivering these modes as analog RGB color signals
at a 31.49 kHz scan frequency. The ZCM-1490 is il-
lustrated in Figure 1-1.
Related publications include the High-Resolution
Analog
RGB Color Video Monitor User's Guide
(595-3924-1 ).
Chapter 1
Introduction
Figure 1-1. ZCM-1490 Color Video Monitor
Specifications
Power input: ...... '.' ....................... .
Video input:
................................ .
Sync input
Horizontal:
............................. .
Vertical:
............................... .
Signal Connector:
........................... .
-
90-135/200-265 VAC, 48-62 Hz,. switch selectable.
Six-foot (1.98
m), 3-wire grounded power cord
included.
Analog
RGB video signal, 0-0.714 V peak-to-peak
(1V peak-to-peak maximum), 75 ohm resistive.
31.49
kHz, ±1 kHz,
positive TIL, 350-line mode,
negative
TIL, 400-line mode,
negative
TIL, 480-line mode.
70 Hz, negative TIL, 350-line mode,
70 Hz, positive TIL, 400-line mode,
60 Hz, negative TIL, 480-line mode.
15-pin subminiature D-type.

CRT: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Flat technology, 14-inch, 0.31 mm pitch, regular tint,
non-glare.
Display' area: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10.07 inches (25.6 cm) wide by 7.67 inches (19.5
cm) high (approximate). Display size remains con-
stant with changes in video modes.
Display colors: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Infinite array of displayable colors. (The actual num-
ber of displayable colors is limited only by the video
source supplying the monitor.)
Characters: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 characters x 25 rows.
Character block: .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 x 19 (Zenith),
9 x 16 (VGA),
Active video time
Horizontal: ............................. .
Vertical: ............................... .
Inactive video time
Horizontal: ............................. .
Page 1-2
8 x 16 (MCGA),
8 x 14 (EGA),
8 x 16 (CGA, 400-line),
9 x 14 (MDA),
9 x 14 (Hercules).
25.42 ~, all modes.
15.4 ms, 640 x 480 (Zenith, VGA),
15.2-ms, 640 x 480 (MCGA),
12.8 ms, 320 x 200-(MCGA),
12.8 ms, 640 x 350 (EGA).
12.8 ms, 320 x 200 (CGA),
12.8 ms, 720 x 350 (MDA),
11.2 ms, 720 x 350 (Hercules).
6.36~. 640 x 480 (Zenith, VGA).
6.35~. 640 x 480 (MCGA).
6.36~. 320 x 200 (MCGA).
6.35~. 640 x 350 (EGA).
6.35 ~. 320 x 200 (CGA).
6.36~. 720 x 350 (MDA),
6.35 ~. 720 x 350 (Hercules).
Introduction

Vertical: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.44 ms, 640 x 480 (Zenith, VGA),
1.44 ms, 640 x 480 (MCGA),
1.56 ms, 320 x 200 (MCGA),
1.56 ms, 640 x 350 (EGA),
1.56 ms, 320 x 200 (CGA),
1.56 ms, 720 x 350 (MDA),
3.15 ms, 720 x 350 (Hercules).
Resolution: ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 640 dots x 480 lines (Zenith, VGA),
640 dots x 480 lines (MCGA),
320 dots x 200 lines (MCGA),
640 dots x 350 lines (EGA),
320 dots x 200 lines (CGA),
720 dots x 350 lines
(M DA),
720 dots x 350 lines (Hercules).
Misconvergence: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.68
mm maximum within display area.
User controls: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power, brightness, contrast, H. CENT (horizontal
Environmental
Temperature:
.. , ........................ .
Humidity: .............................. ,
Altitude:
...... , ................... " ... .
Dimensions:
................................ .
Weight: . " ......................... ,. '" .. .
centering), H. SIZE (horizontal size), V. CENT verti-
cal centering),
V. SIZE (vertical size).
0° to 40° C (32° to 104°F) operating,
-40° 10 60° C (_.40° to 140° F) storage.
10%to 90%, (noncondensing) operating,
0% to 95%, (noncondensing) storage.
-1000 to 10,000 feet (-0.3 to 3.05 km) operating,
40,000 feet (12.2 km) maximum (storage).
14.9 inches (37.9 cm) wide by 12.6 inches (32.0 cm)
high by 15.5 inches (39.4 cm) deep.
40 Ibs (18.1 kg), approximate.
Zenith Data Systems reserves the right to discon-
tinue products and to change specifications at any
time without incorporating these changes into prod-
uctspreviously sold.
Introduction Page 1-3

This chapter provides basic installation and set-up
information for the ZCM-1490 analog color video
monitor. If further adjustment or servicing information
is required, refer to the appropriate chapters which
follow.
Controls and Connections
The various monitor controls and connectors are il-
lustrated in Figures 2-1 and 2-2. Each control and
connector
is explained individually in the following
paragraphs.
-
CONTRAST
CONTROL
\0
-
I
~
J I
Figure 2-1. ZCM-1490 Front View
FOR
Chapter 2
Installation
H CENT
H SIZE
V CENT
TO 1S·PIN RGB CONNECTOR
ON COMPUTER
Figure 2-2. ZCM-1490 Rear View
Power -The rocker-type power switch located
on
the rear panel turns the monitor on or off.
Power-On Indicator- A green LED located
on the
front panel lights when power is applied to the
monitor.
Brightness -The brightness control varies the
overall or average intensity of illumination
of the dis-
play. The average intensity in turn determines the
background level in the display.
Contrast -The contrast control varies the differ-
ence
in intenSity between the black and the white ar-
eas of the display.

Voltage Selection Switch -The voltage selection
switch configures the monitor for operation from
the
appropriate AC power source.
H. CENT -The horizontal centering control adjusts
the left-to-right position of the display within the
screen area. To move the display to the left, turn this
control counterclockwise. To
move the display to the
right, turn this control clockwise.
H. SIZE -The horizontal size control adjusts the
width of the display within the screen area. To in-
crease the display width, tum this control
counterclockwise. To reduce the display width, turn
this control clockwise.
V. CENT-The vertical centering control adjusts the
top-to-bottom position of the display within the screen
area. To move the display upward, turn this control
clockwise. To move the display
dOwnward, turn this
control counterclockwise.
V. SIZE :.- The vertical size control adjusts the
height
01 the display within the screen area. To in-
crease the display height, turn this control
counterclockwise. To reduce the display height, turn
this control clockwise.
Power Input Jack- A 3-pin, grounded-type power
jack
is located on the rear panel.
Power Corel -A 6-foot (1.8
m). 3-wire grounded
and shielde9 power cord supplies power to
the
monitor.
Video Input
cable - A 3.5-100t (1.05 m) cable. ter-
minated with a 15-pin, subminiature D-type connec-
tor. supplies video and sync signals to
the monitor.
The cable
is attached to the monitor and is not
Page 2·2
detachable. Figure 2-3 illustrates the connector and
Table 1-1 lists its pin configuration.
6
Figure 2-3. Subminiature D-type Connector
Table 2-1. Video Input
cable Pin Functions
PIN NUMBER
FUNCTION
1
Red video input
2
Green video input
3 Blue video input
4 NIC
5-
. Reserved (test)
6
Red video ground
7
Green video ground
8
Blue video ground
9
N/C
10 DigitaVsync ground
11
Reserved (mode)
12
N/C
13
Horizontal sync
14
Vertical sync
15
N/C
Installation

Set-Up and Operation
Perform the following steps to set up and operate the
monitor.
1. Place the monitor on a flat surface near the
computer and near
an AC power outlet. Be cer-
tain that the ventilation slots in the cabinet are
not blocked.
2. Connect the video input cable from·the monitor
to the computer.
3. Plug the power cord into the monitor and then
into
an AC outlet. Make sure the voltage selec-
tion switch on the rear panel
is set to the proper
position.
WARNING
Removing or lifting the ground from the AC
power source may present a potentially
lethal shock hazard. Do not use
an AC two-
to-three wire adapter plug with this unit.
4. Tum on the computer and the monitor. The front
panel power indicator should light.
5. Boot an operating system.
6. When a message is displayed on the monitor,
adjust the brightness and contrast controls to
obtain a comfortable display.
Initial Tests
To assess the monitor's operation, perform the color
bar test and the fill screen test. Both tests are
ROM-based.
Installation
Color Bar Test
The color bar test displays an array of colors in the
form of a bar graph. To display the color bars using a
Zenith Data Systems PC-compatible computer:
1. Press the CTRL, ALT, and INS keys in sequence,
hold them, and then release them.
2. After the Monitor prompt appears, type C and
then press RETURN. Color bars should now
be
displayed.
Fill Screen Test
The ROM-based keyboard test can be used to set
the brightness, contrast, dimensions, focus, conver-
gence, and other qualities of the display to comfort-
able levels. To perform the
fill screen test using a
Zenith Data Systems PC-compatible computer:
1. Press the CTRL, ALT, and INS keys in sequence,
hold them, and then release them.
2. After the prompt appears on the monitor, type
-TEST and press RETURN.
3. .Select the keyboard test by pressing the 2 key.
4. Press any displayable key to fill the screen with
that character. (The capital Z
is a good charac-
ter to display for assessing display characteris-
tics.)
Page 2-3

This chapter contains instructions for both disas-
sembly and reassembly of the monitor. Step-by-step
instructions are provided for disassembly. For reas-
sembly, perform the steps in the reverse order unless
instructed otherwise. Read each section (and any
previous sections referred to) completely before dis-
assembling the monitor.
Before proceeding, make sure the power cord and
video cable are disconnected. The overall disas-
sembly sequence for this monitor
is as follows:
1. Remove the rear cover.
2. Remove the rear chassis panels.
3. Remove the video board.
4. Remove the control board.
5. Remove the PIN board.
6. Remove the fan and bottom panel.
7. Remove the support bracket and shield.
8. Remove the deflection board assembly.
9. . Remove the deflection board.
10. Remove the power supply/dynamic focus board
assembly.
11. Remove the power supply and dynamic focus
boards.
12: Remove the CRT.
WARNING
The CRT anode retains a potentially lethal
voltage even when the monitor is turned
off. After removing the monitor cover, dis-
charge the
~RT anode Before proceeding.
with the disassembly. The anode is located
at the top of the CRT and
is shielded by a
white insulating sheet. Refer to Figure
3-1
and the following procedure to discharge
the CRT anode:
Chapter 3
Disassembly
1. Connect a clip lead or heavy gauge wire to
chassis ground.
2. Connect the other end of the lead to the stem of
a flat blade screwdriver that has an insulated
handle.
3. Insert the blade of the screwdriver under the
rubber insulation that covers the anode lead on
the CRT and make contact with the anode ter-
minal. Depending on the amount of charge pre-
sent on the anode, a distinct snap may
be heard
as the CRT anode discharges.
/
/ /
/;
1. CAREFULLY SLIDE A GROUNDED
FLAT SCREWDRIVER TIP UNDER
THE LIP OF THE ANODE LEAD.
2. AFTER DISCHARGING THE VOLTAGE,
DISCONNECT THE ANODE LEAD
FROM THE CRT.
Figure 3-1. CRT Anode Discharging
(

Rear Cover Removal
The rear cover is secured by eight screws. Two of
these screws also secure rubber feet to the bottom of
the monitor cover. After disconnecting the power
cord and video cable, remove these
,eight screws as
shown in Figure 3-2. Slide the cover away from the
monitor, allowing the video cable to pass through the
opening in the cover. Tape the screws to the inside
of the rear cover and set it aside.
Figure 3-2. Rear Cover Removal
Rear Chassis
Panel Removal
Two panels are connected across the back of the
monitor chassis. The upper panel adds support to the
chassis. The lower panel holds the video cable
ground clamp and strain relief. To remove
the
panels:
1. Refer to Figure 3-3 and remove the four hex
screws that secure the upper panel to the chas-
sis side panels. Remove the panel and replace
the four screws into the side panels.
UPPER SUPPORT PANEL
Figure 3·3. Rear Chassls·Panel Removal
Page 3-2 Disassembly

2. Refer to Figure 3-3 and remove the two hex
screws from the bottom sides of the lower panel.
Remove the screw that secures the flyback
transformer bracket to the lower panel. (In some
chassis. all of the high-voltage components are
on the deflection board and this bracket may be
different than the one shown. Adjust the proce-
dure accordingly.) Refer to the inset of Figure
3-3 and remove the hex screw that secures the
ground strap from the video board to the lower
panel. Push the ground strap back through the
slot in the lower panel and gently pull the lower
panel away from the monitor chassis. The video
cable is still held to this panel by its ground
clamp.
3. Refer to Figure 3-3 and remove the two nuts
that secure the video cable ground clamp to the
lower panel. Slide the video cable strain relief
down and out from the lower panel. It may be
necessary to cut the decorative white sheet on
the outside of the lower panel to allow the strain
relief to slide down and away from the panel.
Video Board Removal
1. Remove the rear chassis panels as described
earlier.
2. Refer to Figure 3-4 and loosen the CRT socket
clamp screw.
3. Gently wiggle the video board back and away
from the CRT neck until the CRT is freed from
the socket on the video board. Do not twist the
video board while pulling it away from the CRT.
To prevent damage to both the video board and
the CRT. do not exert excessive force while
removing the video board.
Disassembly
4. Disconnect the following cables entering the
video board: SR9. SA9. SA6. SR6. SS6. and
SA1.
S. Disconnect the following cables leaving the
video board: 6SS (to deflection board). 3RS (to
power supply board). and 8RS (to dynamic focus
board).
6. Disconnect the focus lead connector by twisting
and pulling apart the plastic socket connector on
the lead.
7. Remove the video board.
Figure 3-4. Video Board Removal
Page 3-3

Control Board Removal
The control board holds the external brightness and
contrast controls.
To remove the control board:
1. Refer to Figure 3-5 and slide the control board
back and up from the tracks that hold
it.
2. Disconnect connector SA 1 to the video board
and remove the control board.
Figure 3-5. Control Board Removal
PIN Board Removal
The PIN board is located at the top front portion of
the monitor. It is held in place by two support rails
that span the width of the chassis. To remove the
PIN board:
1. Loosen the support rails. Refer to Figure 3-S
and remove the two hex screws holding each of
the support rails in place.
2. Cut the cable ties indicated in Figure 3-S.
3. Disconnect the following cables entering the PIN
board: SRS, SVS, and SUS.
4. Disconnect the following cables leaving the PIN
board: 4TS (to dynamic focus board).
5. Lift the PIN board and support rails out of the
monitor. The front support rail is held to the
board by plastic standoffs. The rear support rail
is screwed to the two heat sinks on the PIN
board. Remove the rails as necessary.
\b::: __
Figure 3-6. PIN Board Removal
Page 3-4 Disassembly