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CAUTION: Before servicing this chassis, it is important that the service personnel must read the
"Safety Preca
utions" and "Product Safety Notice" in this Service Manual.
CONTENTS
FEATURES...........................................................................................................................2
SAFETY PRECA
UTIONS......................................................................................................2
CHECK OF HIGH VOLTAGE HOLD DOWN CIRCUIT.........................................................2
PRODUCT SAFETY NOTICE...............................................................................................3
SPECIFICATIONS ................................................................................................................3
CONTROLS ..........................................................................................................................4
SIGNAL TIMING CHART ......................................................................................................5
D
ESCRIPTION OF CIRCUIT ................................................................................................7
TRO
UBLESHOOTING.........................................................................................................17
ADJUSTMENTS.................................................................................................................. 20
WIRING DIAGRAM............................................................................................................. 24
BLOCK DIAGRAM .............................................................................................................. 25
P.C.B.A. ASSEMBLY.......................
.................................................................................... 26
REPLACEMENT PARTS LIST............................................................................................ 27
SCHEMATICS..................................................................................................................... 39
SPECIFICATIONS AND PARTS ARE SUBJECT TO CHANGE FOR IMPROVEMENT.
HIGH RESOLUTION COLOR DISPLAY MONITOR
DJ72 Chassis
CM771U
CM772ET
SERVICE MANUAL
SM0401
(V1.0)
(Sept. 2000)
H972
CM771ET
CM772U
MECHANICAL PARTS LIST................................................................................................. 41
DISPLAY ASSEMBLY.......................................................................................................... 42
ATTACHMENT A ................................................................................................................. 45


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2
FEATURES
1. Flat screen CRT with anti-glare, dynamic focus circuit,
dark glass, and INVAR shadow mask give the
sharpest focus and highest contrast.
2. Automatic scanning and automatic adjustment to
conform to a wide range of scanning frequencies and
user requirements.
3. Signal input allows D-Sub Mini 15-pin cable.
4. Power Save Mode automatically puts the monitor into
a standby mode (power consumption less than 15W)
when the H.sync. signal is not detected, and a power -
off mode (less than 5W) when the V.sync. signal is not
detected. Normal mode is restored immediately when
the H. sync. signal and the V.sync. signal are detected.
This feature prolongs monitor life and reduces energy
consumption by up to about 75 %.
SAFETY PRECAUTIONS
NOTICE: Comply with all cautions and safety related
notes located on or inside the cabinet and on the chassis
or picture tube.
The following precautions must be observed.
1. Do not install, remove, or handle the picture tube in
any manner unless shatterproof goggles are worn.
People not so equipped should be kept away while
picture tubes are handled.
2. When replacing a chassis in the monitor, all the
protective devices must be put back in place, such as,
barriers, non-metallic knobs, adjustment and compartment
shields, and isolation resistor-capacitor, etc.
3. When service is required, observe the original lead
dress. Extra precaution should be taken to assure
correct lead dress in the high voltage circuitry area.
4 Always use the manufacturer's replacement components.
Especially critical components as indicated on the
circuit diagram should not be replaced by other
manufacturer's one. Furthermore where a short circuit
has occurred, replace those components that
indicate evidence of overheating.
5. Before returning a serviced monitor to the customer,
the service personnel must thoroughly test unit to be
certain that it is completely safe to operate without
danger of electrical shock, and be sure that no
protective device built into the monitor by the
manufacturer has become defective, or inadvertently
defeated during servicing.
Therefore, the following checks should be performed
for continued protection of the customer and service
technician.
6. In the case of the microprocessor unit, shop
adjustment is necessary after exchange of the
microprocessor unit.
High Voltage
This monitor is provided with a high voltage hold down
circuit for clearly indicating that voltage has increased in
excess of a predetermined value.
Comply with notes described in this Service Manual
regarding this hold down circuit when servicing, so that
this hold down circuit may function correctly.
Service Warning
With minimum Brightness and Contrast the operating
high voltage in this display is lower than 30 kV.
If any component having influence on the high voltage is
replaced, confirm that the high voltage with minimum
Brightness and Contrast is lower than 30 kV.
To measure high voltage use a high impedance
high-voltage meter.
(SENSITIVE RESEARCH Model:
ESH or Equivalent)
Connect (-) to chassis earth and (+) to the CDT anode
button. (See the following connection diagram Fig. 1.)
NOTE: Turn power switch off without fail before making
the connection to the Anode button
CDT ANODE
HIGH IMPEDANCE
H.V. METER
SENSITIVE RESEARCH
Model: ESH or equivalent.
CHASSIS GROUND
FIG. 1
X-radiation
TUBE: The source of X-radiation in this monitor is the
picture tube. The tube utilized in this chassis is specially
constructed to limit X-radiation emissions.
For continued X-radiation protection, the replacement
tube must be the same type as the original, manufacturer
approved type.
When troubleshooting and making test measurements in
a monitor with a problem of excessive high voltage, avoid
being unnecessarily close to the picture tube and the high
voltage components.
Do not operate the chassis longer than is necessary to
locate the cause of excessive voltage.
CHECK OF HIGH VOLTAGE HOLD DOWN
CIRCUIT
Checking of the high Voltage hold down circuit operation.
1. Turn the switch of the unit ON, and set the Brightness
and Contrast controls to max.
2. Turn the switch of the unit OFF.
3. Connect a DC Voltmeter and an adjustment jig as
shown in Fig. 2.
4. Set the adjustment VR to fully counterclockwise.
5. Turn the switch of the unit ON and gradually rotate the
adjustment VR clockwise.
6. Check that a reading of DC voltage-meter is less-than
0.6
0.1 V when picture disappears.
7. Turn the switch of the unit OFF immediately after
checking that the picture disappears.
8. Remove the adjusting jig and the DC voltmeter.
NOTE: Reading of 0.6 V is approximately equivalent to
30 kV of CDT Anode High Voltage.
(+)
(-)


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3
PRODUCT SAFETY NOTICE
Many electrical mechanical parts in the color monitor
units have special safety related characteristics.
These are often not evident from visual inspection nor
can the protection afforded by them necessarily be
obtained by using replacement components rated for
higher voltage, wattage, etc. Replacement parts which
have these special safety characteristics are identified in
this Service Manual.
Electrical components having such features are identified
by marking with
on the schematics and on the parts
list in this Service Manual.
The use of a substitute replacement component which
does not have the same safety characteristics as the
manufacturer recommended replacement one, shown in
the parts list in this Service Manual, may create shock,
fire, X-radiation, or other hazards.
Productions are issued from time to time. For the latest
information, always consult this Service Manual.
DC VOLT METER
(10 V range)
VARIABLE
RESISTER
300 k -B (1/2 W)
Clockwise
RESISTER
68 k (1/2W)
To
CHASSIS
GROUND
DEF BOARD ASSEMBLY
FIG. 2 CHECKING CIRCUIT USING JIG
SPECIFICATIONS
Model Name
CM771U
CM771ET
CM772U
CM772ET
Destination
North America
Europe
North America
Europe
Rated Voltage
AC 100-120 / 200-240 V, Automatically select.
Provided with Power Circuit.
Power Consumption
98 W nominal
Color Display Tube
(CDT)
19 inches diagonal, 0.22 mm horizontal dot pitch,
Invar shadow mask, Black matrix, Anti-Reflection coat, Short persistence phosphors.
Rated
Horizontal
31 - 96 kHz
31 - 96 kHz
31 - 106 kHz
31 - 106 kHz
Frequency Vertical
50 - 160 Hz
Resolution Horizontal
Up to 1600 dots
Up to 1600 dots
Up to 1600 dots
Up to 1600 dots
Vertical
Up to 1280 lines
Up to 1280 lines
Up to 1280 lines
Up to 1280 lines
Signal Inputs
Red, Green and Blue analog video
H/V separate, H/V composite or Sync. on Green sync.
User Controls
Power Switch
Degauss
Language Select
Contrast
Brightness
H. Position
H. Size
V. Position
V. Size
Rotation
Pincushion
Trapezoid
Pin.Balance
Parallelogram
H. Moiré
V. Moiré
Color Select
Red, Green, Blue
DMS Mode
OSD H-Position
OSD V-Position
Dynamic Focus
V.Linearity
V.L. Balance
Hemisphere
Total Reset
Single Recall
Top Corner Pin.
Bottom Corner Pin.
Environmental
Condition
Operation
Storage
Temperature
:
5
to 35
20 to 60
Humidity
:
10 % to 80 %
10 % to 90 %
Dimensions
448(W)
442 (H) 450 (D) mm, Including Tilt & Swivel base.
Weight
24.0 kg
V
R793
R792


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4
CONTROLS
FIG. 3 FRONT VIEW
D-Sub Mini 15-pin
CRT Surface
Front Cover
Control Panel
Tilt & Swivel Base
FIG. 4 CONTROL PANEL
Power Switch
FIG.3 FRONT VIEW
Menu Key
Adjustment Keys
Power Indicator
Power Switch
FIG. 5 REAR VIEW
AC Inlet
Signal Cable
(D-Sub Mini 15-pin)


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5
SIGNAL TIMING CHART
Signal
VGA
640
400
(70Hz)
VESA
800
600
(85Hz)
VESA
1024
768
(85Hz)
VESA
1280
1024
(85Hz)
CM771U-511
CM771ET-301
CM772U-511
CM772ET-301
1
Video
Type
R/G/B Analog
R/G/B Analog
R/G/B Analog
R/G/B Analog
Voltage
0.7 Vp-p
0.7 Vp-p
0.7 Vp-p
0.7 Vp-p
Set Up
None
None
None
None
2
Sync
Type
H/V Separate
H/V Separate
H/V Separate
H/V Separate
Amp.
TTL Level
(Neg./Pos.)
TTL Level
(Pos./Pos.)
TTL Level
(Pos./Pos.)
TTL Level
(Pos./Pos.)
3
Video frequency
25.175 MHz
56.250 MHz
94.500 MHz
157.500 MHz
4
Character (Letter)
640 dots
400 lines
800 dots
600 lines 1024 dots768 lines
1280 dots
1024
lines
5
Horizontal
Frequency
31.469 kHz
53.674 kHz
68.677 kHz
91.146 kHz
Front
porch
0.636 µs (16cl)
0.569 µs (32cl)
0.508 µs (48cl)
0.406 µs (64cl)
Sync.
width
3.813 µs (96cl)
1.138 µs (64cl)
1.016 µs (96cl)
1.016 µs (160cl)
Back
porch
1.907 µs (48cl)
2.702 µs (152cl)
2.201 µs (208cl)
1.422 µs (224cl)
Blanking
width
6.356 µs (160cl)
4.409 µs (248cl)
3.725 µs (352cl)
2.844 µs (448cl)
Display
time
25.422 µs (640cl)
14.222 µs (800cl)
10.836 µs (1024cl)
8.127 µs (1280cl)
H. period
(1H)
31.778 µs (800cl)
18.631 µs (1048cl)
14.561 µs (1376cl)
10.971 µs (1728cl)
6
Vertical
Frequency
70.086 Hz
85.061 Hz
84.997Hz
85.024 Hz
Front
porch
0.381 ms (12H)
0.019 ms (1H)
0.015 ms (1H)
0.011 ms (1H)
Sync.
width
0.064 ms (2H)
0.056 ms (3H)
0.044 ms (3H)
0.033 ms (3H)
Back
porch
1.112 ms (35H)
0.503 ms (27H)
0.524 ms (36H)
0.483 ms (44H)
Blanking
width
1.557 ms (49H)
0.578 ms (31H)
0.582 ms (40H)
0.527 ms (48H)
Display
time
12.711 ms (400H)
11.179 ms (600H)
11.183 ms (768H)
11.235 ms (1024H)
H. period
(1H)
14.268 ms (449H)
11.756 ms (631H)
11.765 ms (808H)
11.761 ms (1072H)
7
Scan System
(Non-interlaced)
(Non-interlaced)
(Non-interlaced)
(Non-interlaced)
8
Signal name
30B
54A
68A
91A
* VGA is a registered trademark of International Business Machined Corporation.
* VESA is a trademark of a nonprofit organization, Video Electronics Standard Association.