Apple Portrait Display Service Manual

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K
Service Source

Macintosh Portrait Display

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K
Service Source

Basics

Macintosh Portrait Display
Page 3

International “Series B”

Apple produced domestic and international versions of the Portrait Display. The troubleshooting and repair procedures differ for each version of the monitor. This manual covers the domestic version only. For documentation on the Portrait Display “Series B,” refer to the international manual.
Page 4
Basics Monitor Distortion - 2

Monitor Distortion

Overview

All large-screen monitors are susceptible to distortions caused by environmental conditions. These distortions are
Ideal Raster
usually not visible on monitors with smaller screens.
Right Edge
Not Straight
Important:
appear distorted when set up in a new environment.
Common environmentally-caused distortions are shown on this and the following pages. Always check first for environmental causes before attempting to repair or adjust a monitor with a distorted raster.
Even monitors set to factory specifications may
Page 5
Basics Monitor Distortion - 3

Environmental Influences

The following environmental conditions may distort the raster of a Portrait Display:
• Proximity to metal objects, such as metal desks, file cabinets, and bookshelves. Metal objects affect the earth’s magnetic field. Earth magnetism usually distorts
Raster Shifted
Up and Left
Raster Shifted
Right
only the edges of the screen.
• Fluorescent lights, other monitors, or electronic appliances such as coffee makers and copy machines. These objects cause dynamic raster distortion, that is, movement or jitter of the image.
Left Side
Bowed Out
Right Side
Bowed In
Page 6
Basics Monitor Distortion - 4

Troubleshooting

Upper-Right Corner
Rounded
S-Shaped
Left Edge
Raster Tilted
Right
Important:
Module swapping cannot fix a monitor with environmental distortion problems, and adjusting a monitor with such problems alters the factory settings.
Note:
If the monitor has shifted up/down or right/left only, go ahead and adjust it using the centering controls. However, keep in mind that if you then move the monitor you may need to readjust the centering controls.
Before adjusting a monitor with a distorted raster, try the following:
• Swivel or move the monitor, or
• Remove the monitor from the building and recheck it in
another location.
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Basics Monitor Distortion - 5
If the display changes (for better or worse) when you move it to another location, the environment is the source of the problem. Relocate the monitor or remove the distortion­causing object.
If the display does not change when you move it to another location, continue troubleshooting the problem (refer to Troubleshooting/Symptom Charts).
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K
Service Source
Specifications
Macintosh Portrait Display
Page 9
Specifications Characteristics - 1

Characteristics

Picture Tube

Screen Resolution

Scan Rates

15-in. diagonal screen Phosphor EIA Type P4 (white) Flat, square, high-contrast, antiglare surface
640x870; 80 dpi Analog 1-, 2-, 4-, or 8-bit pixel depth; permits 256 grays at
8 bits/pixel
Vertical refresh rate: 75 Hz Horizontal scan rate: 68.85 kHz Dot clock: 52 MHz
Page 10
Specifications Characteristics - 2

Active V ideo Display Area

Input Signal

8 in. by 10.87 in. (203 mm by 276 mm)
Video: analog; RS-343 standard
Page 11
Specifications Controls and Ports - 3

Controls and Ports

User Controls

I/O Ports

Rear panel: power switch Right side: brightness and contrast controls
Three Apple Desktop Bus (ADB) connectors
Page 12
Specifications Physical and Electrical - 4

Physical and Electrical

Power Supply

Size and Weight

Universal power supply Voltage: 90–270 VAC, self-configuring Frequency: 47–63 Hz Power: 75 W maximum
Height: 13.1 in. (332 mm) Width: 11.5 in. (292 mm) Depth: 14.9 in. (379 mm) Weight: 35 lb. (16 kg)
Page 13
Specifications Operating Environment - 5

Operating Environment

Temperature

Humidity

Altitude

50°F–95°F (10°C–35°C)
90% maximum, noncondensing
10,000 ft. (3,048 m) maximum
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K
Service Source

Troubleshooting

Macintosh Portrait Display
Page 15
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.
Page 16
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 connections. 3 Check internal power connections. 4 Replace blown fuse. 5 Replace power/sweep board. 6 Replace video board.
Page 17
Troubleshooting Symptom Charts/No Raster
(Continued)
- 3
No Raster
No raster, LED on 1 Ensure monitor’s video cable is connected to the computer or
the video card in the computer. 2 Adjust brightness and contrast knobs. 3 Verify that video card in computer is working properly. 4 Perform video adjustments. 5 Check internal power connections. 6 Replace power/sweep board. 7 Replace CRT board. 8 Replace video board. 9 Replace CRT.
(Continued)
Page 18
Troubleshooting Symptom Charts/Geometry - 4

Geometry

Raster not centered 1 Verify that distortion is not due to environmental conditions.
Move monitor to another location. 2 Perform horizontal or vertical center adjustments. 3 Replace power/sweep board. 4 Replace CRT.
Raster bulges along top of screen
Raster stretched or compressed at top
1 Verify that distortion is not due to environmental conditions.
Move monitor to another location. 2 Replace CRT.
1 Verify that distortion is not due to environmental conditions.
Move monitor to another location. 2 Perform vertical-linearity adjustment. 3 Replace power/sweep board. 4 Replace CRT.
Page 19
Troubleshooting Symptom Charts/GeometryÊ
(Continued)
- 5
Raster short (less than 10 7/8 in. high)
Raster narrow (less than 8 in. wide)
Raster bowed or barrel-shaped
Geometry
1 Perform vertical-height adjustment. 2 Replace power/sweep board. 3 Replace CRT.
1 Perform horizontal-size adjustment. 2 Replace power/sweep board. 3 Replace CRT.
1 Verify that distortion is not due to environmental conditions.
Move monitor to another location. 2 Perform video adjustment. 3 Replace power/sweep board. 4 Replace CRT.
(Continued)
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Troubleshooting Symptom Charts/GeometryÊ
(Continued)
- 6
Raster pyramid shaped (or inverted pyramid)
Geometry
Replace CRT.
(Continued)
Page 21
Troubleshooting Symptom Charts/Video Display - 7

Video Display

Picture is too dark or too bright
Out of focus 1 Perform focus adjustments.
1 Adjust contrast and brightness knobs. 2 Verify that video card in computer is working properly. 3 Perform video adjustments. 4 Replace CRT board. 5 Replace video board. 6 Replace contrast/brightness board. 7 Replace CRT.
2 Replace power/sweep board. 3 Replace CRT.
Page 22
Troubleshooting Symptom Charts/Synchronization - 8

Synchronization

Picture rolls vertically
One thin, bright, horizontal line appears on screen
Picture breaks into diagonal lines
1 Verify that video card in computer is working properly. 2 Replace power/sweep board.
1 Replace power/sweep board. 2 Replace CRT.
1 Connect another monitor to computer and verify video signal. 2 Replace power/sweep board.
Page 23
Troubleshooting Symptom Charts/Miscellaneous - 9

Miscellaneous

Black spots on screen (burnt phosphors)
Picture jitters or flashes
Intermittently shuts down
Replace CRT.
1 Check all ground cable connections. 2 Verify that adjacent computer equipment is properly
grounded. Move electrical devices away from monitor and
shut off fluorescent lights in area. 3 Replace power/sweep board.
1 Ensure monitor’s video cable is connected to the computer or
the video card in the computer. 2 Replace power/sweep board.
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K
Service Source

T ak e Apart

Macintosh Portrait Display
Page 25
Take Apart Rear Cover - 1

Rear Cover

Rear Cover
No preliminary steps are required before you begin this procedure.
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 26
Take Apart Rear Cover - 2
Remove the four case screws and lift the rear cover off the bezel.
Page 27
Take Apart EMI Shield - 3

EMI Shield

Before you begin, remove
EMI Shield
the rear cover.
EMI Shield
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
Note:
includes two metal panels at the top and rear of the monitor chassis. To repair the monitor, remove both panels.
This product
The EMI shield
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Take Apart EMI Shield - 4
1 Remove the three screws
from the rear panel of the EMI shield.
2 Slide the rear panel
forward; then lift the rear panel off the chassis.
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Take Apart EMI Shield - 5
3 Pull up and remove the
top panel from the chassis.
Page 30
Take Apart AC Input Assembly - 6

AC Input Assembly

Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
AC Input
Assembly
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 31
Take Apart AC Input Assembly - 7
1 Remove the screw that
secures the black ground wire to the AC input assembly mounting bracket. Push
P Connector
the ground wire through the hole in the mounting bracket.
Ground Wire
2 Lift the AC input
assembly from the chassis and disconnect the P connector from the power/sweep board.
Note:
Stop here if you are removing the AC input assembly to access another component.
AC Input Assembly
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Take Apart AC Input Assembly - 8
3 Cut the tie-wrap and
remove the P connector from the AC input assembly. Keep the P
Plastic Knob
Tie-Wrap
P Connector
connector.
4 Pull the plastic knob off
the On/Off switch. Keep the knob.
Replacement Note:
When returning a defective AC input assembly, remove and keep the plastic On/Off knob, the P connector, and the fuse. Install these items on the replacement assembly.
Page 33
Take Apart Fuse - 9

Fuse

Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
• Remove AC input
assembly
Fuse
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 34
Take Apart Fuse - 10
Using your fingers or a flat­blade screwdriver, gently pry up one end of the fuse and lift out the fuse.
Page 35
Take Apart Signal Input Assembly - 11

Signal Input Assembly

Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
Signal Input
Assembly
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 36
Take Apart Signal Input Assembly - 12
1 Loosen the screw at the
upper corner of the video board assembly and remove the black ground cable.
2 Disconnect the black
video cable (with the attached ground cable) and the 4-wire cable from the video board.
3 Remove the video cable
Video Cable
and the 4-wire cable from the two cable clamps.
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Take Apart Signal Input Assembly - 13
4 Loosen the screw on the
signal input assembly mounting bracket and remove the black ground cable.
5 Remove the signal input
assembly from the chassis.
Signal Input
Assembly
Page 38
Take Apart Fan - 14
Fan
Before you begin,
• Remove rear cover
Fan
• Remove EMI shield
• Discharge CRT
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 39
Take Apart Fan - 15
1 Open the four cable
clamps.
2 Remove the screw that
secures the fan mounting bracket to the chassis. Remove the mounting bracket, fan, and wire.
3 Disconnect the fan wires
at the fan connector and remove the fan from the mounting bracket.
Note
: Stop here if you are removing the fan assembly to access another component.
Fan Connector
Page 40
Take Apart Fan - 16
4 Remove the two screws
and lockwashers that secure the fan to the mounting bracket.
5 Remove the fan from the
mounting bracket.
Page 41
Take Apart Video Board - 17

Video Board

Before you begin,
• Remove rear cover
• Remove EMI shield
Video Board
• Discharge CRT
• Remove signal input
assembly
• Remove fan
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 42
Take Apart Video Board - 18
1 Remove these
connectors from the video board:
• 3-wire connector S
• 5-wire connector H
• 4-wire connector O
• 6-wire connector C
• 3-wire connector K
2 Remove all connector
wires from cable clamps.
3 Loosen the retaining
screw on the video board case and remove the black ground cable.
Ground Cable
Retaining Screw
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Take Apart Video Board - 19
4 Pull open the left chassis
panel to access the two cables at the bottom of the video board.
5 Remove the video cable
from the cable clamp beneath the video board case and disconnect the cable from the video board.
6 Disconnect the small LED
LED Connector
connector from the video board.
Video Cable
Page 44
Take Apart Video Board - 20
7 Remove the mounting
screw and the video board case from the chassis.
8 Remove the video board
mounting screw through the back of the video board case.
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Take Apart Video Board - 21
9 Remove the plastic cable
clamp from the bottom of the video board case.
10 Depress the three plastic
clips and lift the video board out of the case.
Cable Clamp
Page 46
Take Apart Contrast Brightness Board - 22
Contrast
Contrast Brightness
Board
Brightness Board
Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 47
Take Apart Contrast Brightness Board - 23
1 Disconnect the C
connector from the
Control Knobs
contrast brightness board.
2 Remove the mounting
screw from the contrast brightness board.
3 Pull off the two control
knobs and remove the contrast brightness board. Keep the knobs to
Mounting
Screw
install on the replacement board.
Page 48
Take Apart CRT Board - 24

CRT Board

Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
• Remove AC input
assembly
• Remove signal input
assembly
CRT Board
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 49
Take Apart CRT Board - 25
1 Loosen the screw on the
Video Board Case
video board case and remove the black ground cable.
2 Remove the video cable
from the cable clamp
Ground Cable
beneath the video board case and disconnect the cable from the video board.
Video Cable
Page 50
Take Apart CRT Board - 26
3 Pull open the right
chassis panel enough to gain access to the upper connectors on the CRT board.
4
Caution:
CRT is easily damaged. Do not apply force to the neck of the CRT when removing connectors from the CRT board.
Support the CRT board with one hand and disconnect the 2-wire 4-pin connector F, and the 3-wire connector K.
The neck of the
Page 51
Take Apart CRT Board - 27
5 Remove the cables and
the ferrite ring from the cable clamp beneath the CRT board.
Cable Clamp
Ferrite Ring
Page 52
Take Apart CRT Board - 28
6 Loosen the screw on the
ring clamp that secures the CRT board to the neck of the CRT.
7
Caution:
Twisting, bending, or applying force to the CRT board could damage the neck of the CRT. Pull the CRT board straight off the
Metal Cover
neck of the CRT.
Grasp the metal cover that protects the CRT board and carefully pull the board straight off the CRT.
Page 53
Take Apart CRT Board - 29
8 Disconnect the following
cable connectors from the bottom of the CRT board:
• 4-wire connector O
• 4-wire connector T
• 5-wire connector D
Page 54
Take Apart CRT Board - 30
9 Using needlenose pliers,
remove the plastic standoff from the bottom of the metal cover. Keep the standoff and use it to install the replacement CRT board.
10 Slide the CRT board out
of the metal cover. Keep the cover for installation on the replacement CRT board.
Page 55
Take Apart Power/Sweep Board - 31

Power/Sweep Board

Power/Sweep Board
Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
• Disconnect anode cap
• Remove AC input assembly
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 56
Take Apart Power/Sweep Board - 32
1 Disconnect the following
connectors from the power/sweep board:
• 2-wire connector T
• Single connector GB
2 Unravel the GB
connector cable from the large red anode cable.
Anode Cable
Page 57
Take Apart Power/Sweep Board - 33
3 Disconnect the fan cable
at the fan connectors.
Fan Cable
Connectors
Fan
Anode Cable
Cable Clamps
4 Remove the fan cable
and the large red anode cable from the three cable clamps.
Page 58
Take Apart Power/Sweep Board - 34
5 Pull open the right
chassis panel.
6 Disconnect the following
connectors from the power/sweep board:
• 8-wire connector H
• 5-wire connector D
• 2-wire connector F
• 4-wire connector M
7 Remove the screw that
secures the black ground cable to the top of the chassis.
Page 59
Take Apart Power/Sweep Board - 35
8 Remove the two screws
with captive lockwashers from the outside of the right chassis panel.
9
Note:
Do not attempt to remove the power/ sweep board from its plastic cover. When returning a defective power/sweep board to Apple, return the board and cover as a unit.
Depress the release latch and pull the power/ sweep board off the chassis.
Page 60
Take Apart Bezel - 36

Bezel

Bezel
Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 61
Take Apart Bezel - 37
1 With the monitor face-
down on a protective pad, remove the four screws that secure the bezel to the chassis.
Page 62
Take Apart Bezel - 38
2 Set the monitor upright
on a protective pad.
3 Slightly lift the chassis
and pull off the top and then the bottom of the bezel.
Page 63
Take Apart LED Cable Assembly - 39

LED Cable Assembly

Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
• Remove bezel
LED Cable Assembly
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 64
Take Apart LED Cable Assembly - 40
1 Disconnect the small LED
connector from the bottom of the video board. Remove the LED cable from the cable clamp.
LED Connector
Page 65
Take Apart LED Cable Assembly - 41
2 With the monitor face-
down on a protective pad, pull the small LED cable connector from the chassis access hole.
3 Remove the screw that
secures the LED mounting bracket to the
LED Cable Connector
chassis.
Page 66
Take Apart LED Cable Assembly - 42
4 Remove the screw from
the LED board.
5 Cut the tie-wrap and
remove the LED cable assembly from the mounting bracket.
Mounting Bracket
Tie-Wrap
LED Cable
Page 67
Take Apart CRT - 43
CRT
Before you begin,
• Remove rear cover
• Remove EMI shield
• Discharge CRT
• Remove anode cap
• Remove AC input assembly
CRT
• Remove signal input assembly
• Remove CRT board
• Remove bezel
• Remove LED assembly
Page 68
Take Apart CRT - 44
Anode Cable
Cable Clamp
CRT Cable
Warning:
This product contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
1 Disconnect the 4-wire
CRT connector M, and the single-wire connector GB from the power/ sweep board.
2 Remove the CRT cable
from the cable clamp at the bottom of the chassis and unwrap the GB cable.
Page 69
Take Apart CRT - 45
3 Remove and discard the
copper tape from both sides of the CRT and chassis. (Two new strips of copper tape ship with the replacement CRT.)
Copper
Tape
Page 70
Take Apart CRT - 46
4 Remove the four
mounting screws from the CRT.
5 Caution: The neck of the
CRT is easily damaged. Do not grab the neck of the CRT to remove it from the bezel.
Carefully grasp and pull the sides of the CRT from the chassis.
Page 71
K
Service Source

Adjustments

Macintosh Portrait Display
Page 72
Adjustments Monitor Safety - 2

Monitor Safety

When adjusting this monitor, be sure to follow all CRT safety instructions outlined in Bulletins/Safety. Make sure you are familiar with these warnings and cautions:
Warning:
high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
Warning:
monitor. Position a mirror to view the screen. Do not reach around the monitor to adjust the controls.
Caution
Switch off the monitor before connecting and disconnecting the alligator clips to/from the test points.
The Portrait Display contains high voltage and a
Adjustments are made from the rear of the
: When measuring voltage, avoid a possible short.
Page 73
Adjustments Light Meter Setup - 3

Light Meter Setup

This topic covers setup for three light meter models: R77, L-248, and 246. Model R77 (Apple part number 076-0310) is the newest model available.

Model R77

The R77 light meter is capable of reading luminance from 10 to 1,000 footcandles (fc).
Before you begin, remove the 10X multiplier plate
Page 74
Adjustments Light Meter Setup - 4
from the lens.
Three scales are shown on the light meter:
• 200-1000 fc
• 50-250 fc
• 10-50 fc
Because display screen luminance typically ranges from 10 to 50 fc, take readings from the bottom scale only.
Page 75
Adjustments Light Meter Setup - 5
To measure a display screen’s luminance,
1 Set the scale switch to
the bottom position (to set up the 10-50 fc scale).
2 Place the lens against the
middle of the screen and read the bottom scale.
Note:
When the light meter is not in use, slide the scale switch to its top position, and store the meter in its protective case.
Important:
light meter is giving false
If you suspect the
Page 76
Adjustments Light Meter Setup - 6
readings, verify the readings with a known-good light meter or photometer. Also check the age of the R77 light meter by its four-digit manufacturing date stamp (such as 0398 for March
1998).
Caution:
meter can permanently damage its accuracy. A shock-damaged meter might read incorrectly or its pointer may not drop to zero.
Dropping the
Page 77
Adjustments Light Meter Setup - 7
Side Switch
Scale
Lens
Read Button
Red Area

Model L-248

1 Press the red button on
the back of the light meter. If the reading is out of the red area, replace the battery.
2 Move the side switch to
its upper position so that the scale reads 10 through 18.
3 Uncover the lens of the
meter.
4 Place the lens against the
middle of the screen and press the read button to read the scale.
Page 78
Adjustments Light Meter Setup - 8

Model 246

1 Remove the metal slide,
Lens
if installed, from the top of the light meter.
Swivel Head
Scale
2 Install the white lens
with the red dot.
3 Rotate the swivel head
so the lens of the meter faces the monitor.
Place the lens against the middle of the screen and read the scale.
Page 79
Adjustments Geometry - 9

Geometry

Before you begin, remove the rear cover.
Phase
V.Lin
H.F.
V.F.
Focus
H.Size
H.Cent
Height V.Cent
Warning:
This product contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
Note:
Geometry adjustments may be necessary whenever you replace the power/ sweep board.
Page 80
Adjustments Geometry - 10

Horizontal Size

1 Use Display Service
Utility to display the All-White Screen test
All-White
Screen
H.Size
pattern.
2 Using the plastic
screwdriver, adjust the horizontal size (H.Size) control until the raster width is 8 inches (± 1/8 inch) or 203 mm (± 2 mm).
Page 81
Adjustments Geometry - 11

Horizontal Center

1 Using the plastic
screwdriver, adjust the horizontal center
All-White
Screen
H.Cent
(H.Cent) control until the raster is centered (left to right) in the display area.
2 Verify that the raster
width is 8 inches (± 1/8 inch) or 203 mm (± 2 mm) wide. If it is not, repeat the horizontal size and horizontal center adjustments.
Page 82
Adjustments Geometry - 12

Horizontal Phase

1 Measure the black
margin on the right side of the display. The black
All-White
Screen
H.Phase
margin should measure 1/4 inch or 7 to 8 mm from the right edge of the white raster to the edge of the plastic bezel.
2 If necessary, use the
plastic screwdriver to adjust the horizontal phase (H.Phase) control until the black margin is 1/4 inch or 7 to 8 mm wide.
Page 83
Adjustments Geometry - 13

Height

Using a plastic screwdriver, adjust the height control
All-White
Screen
Height
until the raster height is 10 7/8 inches (± 1/8 inch) or 276 mm (± 2 mm).
Page 84
Adjustments Geometry - 14

Vertical Center

1 Using the plastic
screwdriver, adjust the vertical center (V.Cent)
All-White
Screen
V.Cent
control until the raster is centered (top to bottom) in the display area.
2 Verify that the raster
height is 10 7/8 inches (± 1/8 inch) or 276 mm (± 2 mm). If it is not, repeat the height and vertical center adjustments.
Page 85
Adjustments Geometry - 15

Vertical Linearity

1 Use Display Service
Utility to display the Crosshatch test pattern.
Crosshatch
V.Lin
2 Using a plastic
screwdriver, adjust the vertical linearity (V.Lin) control until the boxes at the top of the display are the same size as those at the bottom.
Page 86
Adjustments Geometry - 16

Focus

Brightness Contrast
Focus
1 Use Display Service
Utility to display the Focus test pattern.
2 Set the external
contrast control to maximum (turn fully clockwise) and the external brightness control to the center (detent) position.
Page 87
Adjustments Geometry - 17
3 Using a plastic
screwdriver, adjust the focus controls as follows:
• Adjust the focus control for the best
Focus
overall focus
• Adjust the H.F.
H.F.
control for the best focus along the left
V.F.
and right edges of the display
Focus
• Adjust the V.F. control for the best focus at the top and bottom
• Repeat the adjustments until you have attained the best focus possible
Page 88
Adjustments Video With Screen Control - 18

Video With Screen Control

Before you begin, remove
Screen
Brightness
Contrast
GAIN
the following:
• Rear cover
• EMI shield
If the monitor doesn’t have a screen control, go to “Video Without Screen Control.”
SUB-
BRIGHT
Cutoff
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
Page 89
Adjustments Video With Screen Control - 19
Gray Bars
Caution:
To prevent damaging the monitor, reinstall the signal input board with the two mounting screws.
Note:
Perform the video adjustments whenever the CRT or video board has been replaced or the display appears to be maladjusted.
1 Switch on the monitor
and let it warm up for at least 10 minutes.
2 Use Display Service
Utility to display the Gray Bars test pattern.
Page 90
Adjustments Video With Screen Control - 20
3 Using a plastic
screwdriver, preset the following controls:
• Screen control to
Gray Bars
maximum (turn fully clockwise)
Screen
• GAIN control to its midpoint
• SUB-BRIGHT control to maximum (turn fully clockwise)
GAIN
SUB-BRIGHT
Power Switch
Page 91
Adjustments Video With Screen Control - 21

Cutoff

1 Use Display Service
Utility to display the
All-Black Screen
Brightness
Contrast
All-Black Screen test pattern.
2 Set the contrast control
and the brightness control to maximum (turn fully clockwise).
Page 92
Adjustments Video With Screen Control - 22
Note:
If you turn the cutoff control up (clockwise) too far, the monitor may shut down. If this happens,
All-Black Screen
switch off the monitor, turn the cutoff control all the way down, and wait 30 seconds. Then resume the adjustment.
3 Using the plastic
screwdriver, adjust the cutoff control clockwise until retrace lines are just visible.
4 Then turn the cutoff
Cutoff
control counterclock­wise until the retrace lines just disappear.
Page 93
Adjustments Video With Screen Control - 23

Sub-Brightness

1 Use Display Service
Utility to display the Gray Bars test pattern.
Gray Bars
2 Set the brightness
control to the center (detent) position.
Brightness
SUB-BRIGHT
3 Set the SUB-BRIGHT
control so that the leftmost bar is completely black.
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Screen Luminance

1 Use Display Service
Utility to display the All-White Screen test
All-White Screen
pattern.
Important:
light meter models R77, L-248, and 246 differ. Please note which meter you are using before making adjustments. (See “Light Meter Setup” in this chapter.)
Readings from
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Adjustments Video With Screen Control - 25
2 Measure screen
luminance with the light meter. You should get 40 foot lamberts (± 3
All-White Screen
foot lamberts), which on the light meter is
• Model R77: 29 on the bottom scale
• Model L-248: 10 to 11 on the 10–18 scale
• Model 246: 29 on the red scale
Important:
Over time, light meter tolerances can vary. If in doubt, verify the readings with a known-good light meter or photometer.
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3 Set the brightness
control to the center position, and recheck the screen luminance. The
All-White Screen
reading should not go beyond 60 fL, which on the light meter is
• Model R77: 40 on the bottom scale
Brightness
• Model L-248: 11 to 12 on the 10–18 scale
GAIN
• Model 246: 40 on the red scale
4 If necessary, repeat the
SUB-BRIGHT
SUB-BRIGHT and GAIN adjustments until you obtain a correct reading.
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Video Without Screen Control

Before you begin, remove the following:
• Rear cover
Brightness
Contrast
GAIN
BIAS
SUB-
BRIGHT
TP1
TP2
Cutoff
• EMI shield
Warning:
contains high voltage and a high-vacuum picture tube. To prevent serious injury, review CRT safety in Bulletins/Safety.
This product
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Adjustments Video Without Screen Control - 28
Caution:
damaging the monitor, reinstall the signal input board with the two mounting screws.
Note:
adjustments whenever the CRT or video board has been replaced or the display appears to be maladjusted.
To prevent
Perform the video
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Bias

1 Switch on the monitor
and let it warm up for at least 10 minutes.
All-Black Screen
Brightness
Contrast
SUB-BRIGHT
Power Switch
2 Preset the SUB-BRIGHT
control to minimum (fully counterclock­wise).
3 Use Display Service
Utility to display the All-Black Screen.
4 Set the brightness
control and contrast control to minimum (turn fully counter­clockwise).
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Adjustments Video Without Screen Control - 30
Note:
For accurate voltage measurements, use two shielded alligator clip leads and a high quality DC voltmeter.
TP1
TP2
Power Switch
Caution
: To avoid a short, switch off the monitor before connecting the alligator clips.
5 Switch off the monitor.
6 Connect one end of a
shielded alligator clip lead to TP1 on the CRT board. Connect the other end to the positive probe of a DC voltmeter.
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