Apple Portrait Display Service Manual

K

Service Source

Macintosh Portrait Display

K

Service Source

Basics

Macintosh Portrait Display

Basics International “Series B” - 1

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.

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

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

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.

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).

K

Service Source

Specifications

Macintosh Portrait Display

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

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

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

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)

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

K

Service Source

Troubleshooting

Macintosh Portrait 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 connections.
3 Check internal power connections.
4 Replace blown fuse.
5 Replace power/sweep board.
6 Replace video board.

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)

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.

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)

Troubleshooting Symptom Charts/GeometryÊ

(Continued)

- 6

Raster pyramid
shaped (or inverted
pyramid)

Geometry

Replace CRT.

(Continued)

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.

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.

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.

K

Service Source

T ak e Apart

Macintosh Portrait Display

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

Take Apart Rear Cover - 2

Remove the four case screws
and lift the rear cover off
the bezel.

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

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.

Take Apart EMI Shield - 5

3 Pull up and remove the

top panel from the
chassis.

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

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

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.

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

Take Apart Fuse - 10

Using your fingers or a flat­blade screwdriver, gently
pry up one end of the fuse
and lift out the fuse.

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

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.

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

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

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

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.

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

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

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

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.

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

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

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.

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

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

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

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

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.

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

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.

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

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

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.

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.

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.

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

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.

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.

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

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

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.

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

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

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.

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

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.

K

Service Source

Adjustments

Macintosh Portrait Display

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.

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

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.

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

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

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.

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.

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.

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).

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.

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.

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).

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.

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.

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.

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

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

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.

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

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).

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.

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.

Adjustments Video With Screen Control - 24

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

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.

Adjustments Video With Screen Control - 26

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.

Adjustments Video Without Screen Control - 27

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

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

Adjustments Video Without Screen Control - 29

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).

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.