Apple 12 Rgb Display Service Manual
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Service Source
Macintosh 12 RGB Display
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Service Source
Specifications
Macintosh 12" RGB Display
Specifications Characteristics - 1
Characteristics
Picture Tube
Screen Resolution
Scan Rates
12-in. viewable diagonal screen
90° deflection angle; black matrix-type dot screen
Phosphor type P22 (aluminized)
Spherical, antiglare surface
512x384 lines; 64 dpi
Displays up to 256 colors with Macintosh Display Card 4•8 and
16.7 million colors with Macintosh Display Card 8•24
Vertical refresh rate: 60.15 Hz
Horizontal scan rate: 24.48 kHz
Rise and fall time: 27 ns maximum
Specifications Characteristics - 2
Active V ideo Display Area
Input Signals
8.08 in. by 6.02 in. (205 mm by 153 mm)
Video: red, green, and blue analog video; RS-343 standard
Specifications Controls - 3
Controls
User Controls
Rear panel: power switch
Right side: brightness and contrast controls
Specifications Physical and Electrical - 4
Physical and Electrical
Power Supply (International)
Power Supply (Domestic)
Size and Weight
Universal power supply
Voltage: 90–270 VAC, self-configuring
Frequency: 47–63 Hz, single-phase
Power: 90 W maximum
Voltage: 100–120 VAC
Frequency: 50–60 Hz
Power: 90 W maximum
Height: 12.2 in. (310 mm)
Width: 14.4 in. (365 mm)
Depth: 10.0 in. (253 mm)
Weight: 35 lb. (15.9 kg)
Specifications Operating Environment - 5
Operating Environment
Temperature
Humidity
Altitude
50°F–104°F (10°C–40°C)
95% maximum, noncondensing
10,000 ft. (3,048 m) maximum
104°F (40°C) operation from 0–7000 ft. (2,134 m) and derated
linearly to maximum 64°F (25°C) at 10,000 ft.
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Service Source
Troubleshooting
Macintosh 12" RGB Display
Troubleshooting General - 1
General
The Symptom Charts included in this chapter will help you
diagnose specific symptoms related to your product. Because cures
are listed on the charts in the order of most likely solution, try
the first cure first. Verify whether or not the product continues to
exhibit the symptom. If the symptom persists, try the next cure.
(Note: If you have replaced a module, reinstall the original module
before you proceed to the next cure.)
If you are not sure what the problem is, or if the Symptom Charts
do not resolve the problem, refer to the Flowchart for the product
family.
For additional assistance, contact Apple Technical Support.
Troubleshooting Symptom Charts/No Raster - 2
Symptom Charts
No Raster
No raster, LED off 1 Ensure monitor’s video cable is connected to the computer or
the video card in the computer.
2 Check power cord.
3 Check internal power connectors.
4 Replace blown fuse.
5 Replace external power cable assembly.
6 Replace main deflection board.
No raster, LED on 1 Ensure monitor’s video cable is connected to the computer or
the video card in the computer.
2 Adjust contrast and brightness user controls.
3 Verify that video card in monitor is working properly.
4 Check main deflection board and CRT/video board connectors.
5 Replace blown fuse.
6 Perform screen adjustment.
7 Replace main deflection board.
8 Replace CRT/video board.
9 Replace CRT.
Troubleshooting Symptom Charts/Geometry - 3
Geometry
Raster size short/
tall, narrow/wide
Raster not centered 1 Verify that distortion is not due to environmental conditions.
Horizontal linearity
bad (screen sides
differ)
1 Adjust V-HEIGHT or H-WIDTH controls on main deflection
board.
2 Replace main deflection board.
3 Replace CRT.
Move monitor to another location.
2 Adjust H-CENT or V-CENT external controls.
3 Replace main deflection board.
Replace main deflection board.
Troubleshooting Symptom Charts/Geometry
(Continued)
- 4
Geometry
Vertical linearity bad
(screen top and
bottom differ)
Raster bows 1 Verify that distortion is not due to environmental conditions.
1 Adjust V-LIN control on main deflection board.
2 Replace main deflection board.
Move monitor to another location.
2 Check V-HEIGHT and V-CENT adjustment controls and H-
WIDTH and H-CENT controls. (Some bowing from
environmental conditions is normal and is within
manufacturing tolerances. Slight bowing does not impair
functionality of monitor.)
3 Replace main deflection board.
4 Replace CRT.
(Continued)
Troubleshooting Symptom Charts/Geometry
(Continued)
- 5
Geometry
Entire raster is tilted 1 Verify that distortion is not due to environmental conditions.
Move monitor to another location.
2 Adjust yoke assembly as follows:
• Switch off power and remove rear cover
• Loosen frontmost screw on neck of CRT
• Twist yoke assembly as appropriate
• Retighten screw on neck of CRT (Do not overtighten screw;
• Switch on monitor and check display
3 Replace main deflection board.
(Continued)
you could break neck of CRT.)
Troubleshooting Symptom Charts/Geometry
(Continued)
- 6
Abnormal/distorted
raster (other than
above)
Geometry
1 Verify that distortion is not due to environmental conditions.
Move monitor to another location.
2 Check all cable connections.
3 Perform geometric adjustments.
4 Replace main deflection board.
5 Replace CRT/video board.
6 Replace CRT.
(Continued)
Troubleshooting Symptom Charts/Synchronization - 7
Synchronization
Picture breaks into
diagonal lines
Picture rolls
vertically
Single vertical or
horizontal line on
screen
1 Connect another monitor to computer and verify video signal.
2 Adjust H-HOLD control on main deflection board.
3 Replace main deflection board.
1 Verify that video card in monitor is working properly.
2 Adjust V-HOLD control on main deflection board.
3 Replace main deflection board.
1 Check yoke connector DY.
2 Replace main deflection board.
3 Replace CRT.
Troubleshooting Symptom Charts/Video - 8
Video
Predominant red,
blue, or green tint
Picture too dark or
too bright
1 Check video cable connection.
2 Verify that video card in monitor is working properly.
3 Perform white balance adjustments.
4 Replace CRT/video board.
5 Replace CRT.
1 Adjust contrast and brightness knobs.
2 Verify that video card in monitor is working properly.
3 Perform video adjustments (cutoff and white balance).
4 Replace main deflection board.
5 Replace CRT/video board.
6 Replace CRT.
Troubleshooting Symptom Charts/Video
(Continued)
- 9
Video
Cannot adjust
brightness, contrast,
or color
Out of focus 1 Adjust focus control on flyback transformer.
1 Replace contrast/brightness assembly.
2 Replace main deflection board.
3 Replace CRT/video board.
2 Perform screen adjustment.
3 Replace main deflection board.
4 Replace CRT.
(Continued)
Troubleshooting Symptom Charts/Miscellaneous - 10
Miscellaneous
Intermittently shuts
down
Picture jitters or
flashes
Flashing or wavy
screen
Black spots on screen
(burnt phosphors)
1 Ensure monitor’s video cable is connected to the computer or
the video card in the computer.
2 Replace main deflection board.
1 Check that ground cables are secure.
2 Check that adjacent computer equipment is properly
grounded. Move other electrical devices away from monitor.
Shut off fluorescent lights.
3 Replace main deflection board.
1 Crimp metal connector tabs on video connector.
2 Replace main deflection board.
Replace CRT.
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Service Source
T ak e Apart
Macintosh 12" RGB Display
Take Apart Rear Cover - 1
Rear Cover
No preliminary steps are
required before you begin
this procedure.
±
Rear Cover
Warning:
contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.
This product
Take Apart Rear Cover - 2
1 Place the monitor face-
down on a protective pad
and remove the two case
screws.
2 Separate the bottom of
the rear cover from the
bezel.
Take Apart Rear Cover - 3
3 Set the monitor upright.
4 Press down about one
inch from the outside
edges of the bezel to
separate the top of the
rear cover from the
bezel.
Take Apart Rear Cover - 4
5 Place the monitor face-
down on a protective pad.
6 Lift off the loosened
rear cover.
7 Pull the AC power cord
and video cable through
the cover.
Take Apart Contrast/Brightness Assembly - 5
Contrast/ Brightness Assembly
Contrast/Brightness
Assembly
Before you begin,
• Remove the rear cover
• Discharge the CRT
• Remove the anode cap
±
Warning:
contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.
±
Warning:
This product
Never use a
Take Apart Contrast/Brightness Assembly - 6
grounding wriststrap until
after discharging the CRT.
J204
1 Disconnect the six-wire
cable from connector
J204 on the CRT/video
Cable Retainer
board. Remove the six
wires from the cable
retainer.
Mounting Bracket
2 Remove brightness
VR204
board VR204 and
contrast board VR203
from the mounting
VR203
bracket.
3 Unhook and pull the six
wires through the back
of the mounting bracket.
Take Apart Contrast/Brightness Assembly - 7
4 Pull off the two control
knobs.
5 Disconnect cable
J206
connector J206 from the
brightness board and
cable connector J205
Brightness Board - VR204
Plastic Control Knobs
J205
from the contrast board.
Contrast Board
VR203
Take Apart Fuse - 8
Fuse
Before you begin,
• Remove the rear cover
• Discharge the CRT
• Remove the anode cap
±
Fuse
Warning:
contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.
±
Warning:
grounding wriststrap until
after discharging the CRT.
This product
Never use a
Take Apart Fuse - 9
Using a small flat-blade
screwdriver, pry the
defective fuse from
connector F901 on the
deflection board.
F901
Take Apart CRT/Video Board - 10
CRT/Video Board
Before you begin,
• Remove the rear cover
• Discharge the CRT
• Remove the anode cap
±
CRT/Video Board
Warning:
contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.
±
Warning:
grounding wriststrap until
after discharging the CRT.
This product
Never use a
Take Apart CRT/Video Board - 11
1 Remove the screw that
secures the video cable
to the cable clamp at the
back of the CRT/video
board.
2 Remove the video cable
from the clamp and
remove the clamp from
the CRT/video board.
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