Apple Applecolor Highres Rgb Mon Service Manual

K

Service Source

AppleColor High-Res RGB

Monitor

K

Service Source

Specifications

AppleColor High-Resolution

RGB Monitor

Specifications Characteristics - 1

Characteristics

Picture Tube

Screen Resolution

Scan Rates

13-in. viewable diagonal screen

0.26 mm aperture grille pitch
Trinitron CRT

640x480; 69 dpi
Displays up to 16.7 million colors with Macintosh Display Card

4•8, 8•24, or 8•24GC

Vertical refresh rate: 66.7 Hz
Horizontal scan rate: 35.0 kHz
Dot clock: 30.24 MHz

Specifications Characteristics - 2

Active V ideo Display Area

Input Signals

9.3 in. by 6.9 in. (235 mm by 176 mm)

Video: red, green, and blue analog signals; RS-343 standard

Specifications Controls - 3

Controls

User Controls

Adjustment Controls

Rear panel: power switch and degauss switch
Right side: brightness and contrast controls

Vertical misconvergence adjustment
Horizontal misconvergence adjustment

Specifications Physical and Electrical - 4

Physical and Electrical

Power Supply

Size and Weight

Universal power supply
Voltage: 85–270 VAC
Frequency: 47–63 Hz
Power: 90 W

Height: 11 in. (281 mm)
Width: 13.5 in. (344 mm)
Depth: 15.2 in. (385 mm)
Weight: 34 lb. (15.5 kg)

Specifications Operating Environment - 5

Operating Environment

Temperature

Humidity

Altitude

50°F–104°F (10°C–40°C)

90% maximum, noncondensing

10,000 feet (3,048 m) maximum

K

Service Source

Troubleshooting

AppleColor High-Resolution

RGB Monitor

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
(condition may occur
after monitor has
been on for a few
minutes)

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 If deflection board is Rev. A board, replace high-voltage

capacitor.
6 Replace deflection board D.
7 Replace power supply.

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 contrast and brightness knobs.
3 Check power supply and deflection board D connections.
4 Verify that video card in computer is working properly.
5 Replace video board C.
6 Replace video color board assembly.
7 Replace CRT.

(Continued)

Troubleshooting Symptom Charts/Geometry - 4

Geometry

Raster size small/
large, short/tall,
narrow/wide

Raster not centered 1 Verify that distortion is not due to environmental conditions.

Note:

When using the Rev. A version of the High-Resolution RGB
Monitor with a Macintosh LC, the width of the raster/image area
is reduced 3/16 inch from both sides of the screen. Adjust the
horizontal size.

1 Adjust horizontal or vertical size.
2 Replace deflection board D.
3 Replace CRT.

Move monitor to another location.

2 Adjust horizontal shift or vertical shift control (as

appropriate) on video board H.

3 Replace deflection board D.

Troubleshooting Symptom Charts/Geometry

(Continued)

- 5

Geometry

Vertical linearity bad
(screen top and
bottom differ)

Raster fades in and out Replace video board C.

Abnormal/distorted
raster (other than
above)

1 Adjust V.LIN control.
2 Replace deflection board D.

1 Verify that distortion is not due to environmental conditions.

Move monitor to another location.
2 Verify that all connectors are correctly placed and secure.
3 Perform appropriate geometry adjustments.
4 Replace deflection board D.

(Continued)

Troubleshooting Symptom Charts/Synchronization - 6

Synchronization

Picture breaks into
diagonal lines

Picture rolls
vertically

Single vertical line on
screen

1 Connect another monitor to computer and verify video signal.
2 Replace deflection board D.

1 Connect another monitor to computer and verify video signal.
2 Verify that video card in computer is working properly.
3 Replace deflection board D.

1 Check yoke connectors.
2 Replace deflection board D.
3 Replace CRT.

Troubleshooting Symptom Charts/Synchronization

(Continued)

- 7

Single horizontal line
on screen

Synchronization

Note:

A thin, gray, horizontal line may be visible across the
bottom third of a lit screen. This line is inherent in the design of
Trinitron monitors. Do not replace modules.

Otherwise,

1 Check yoke connectors.
2 Replace deflection board D.
3 Replace CRT.

(Continued)

Troubleshooting Symptom Charts/Video - 8

Video

Predominant red,
blue, or green tint

Picture too dark or
too bright

1 Verify that video card in computer is working properly.
2 Check monitor-to-computer connections.
3 Perform white balance adjustments.
4 Replace video color board assembly.
5 Replace CRT.

1 Adjust brightness and contrast knobs.
2 Verify that video card in computer is working properly.
3 Set cutoff control on video board H.
4 Adjust white balance.
5 Replace video color board assembly.
6 Replace deflection board D.

Troubleshooting Symptom Charts/Video

(Continued)

- 9

Video

Cannot adjust
brightness or
contrast

Picture out of focus 1 Adjust focus control on video board H.

1 Replace video color board assembly.
2 Replace contrast control board J.

2 Replace deflection board D.
3 Replace video board C.
4 Replace video color board assembly.
5 Replace CRT.

(Continued)

Troubleshooting Symptom Charts/Video

(Continued)

- 10

Picture out of focus
with color-shadowed
characters

Video

Note:

problem. (If you see no color and the display is fuzzy or the
characters on the focus pattern are unclear, the problem is focus
rather than convergence.)

1 Perform convergence adjustment; then adjust focus control

2 Replace deflection board D.
3 Replace CRT.

(Continued)

Colors in the crosshatch pattern indicate a convergence

on video board H if necessary.

Troubleshooting Symptom Charts/Miscellaneous - 11

Miscellaneous

Intermittently shuts
down (LED does not
light)

Picture jitters or
flashes

Black screen spots
(burnt phosphors)

1 Ensure monitor’s video cable is connected to the computer or

the video card in the computer.
2 Perform cutoff adjustment.
3 Replace high-voltage capacitor.
4 Replace deflection board D.

1 Check that all ground cables are secure.
2 Verify that adjacent computer equipment is properly

grounded. Move electrical devices away from monitor.

Temporarily shut off fluorescent lights.
3 Replace deflection board D.

Replace CRT.

Troubleshooting Symptom Charts/Miscellaneous

(Continued)

- 12

Monitor emits high­pitched noise

Degauss button does
not correct uneven
patches of color

Miscellaneous

Replace deflection board D.

Replace power supply.

(Continued)

K

Service Source

T ak e Apart

AppleColor High-Resolution

RGB Monitor

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.

±

Warning:

grounding wriststrap until
after discharging the CRT.

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

This product

Never use a

Take Apart EMI Shield - 2

EMI Shield

Before you begin,

• Remove the rear cover

EMI Shield

• Discharge the CRT

±

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 EMI Shield - 3

1 Remove the five screws

that secure the EMI
shield to the chassis.

±

2

EMI Shield

Anode Wire

Cable Clamp

Warning:

touch the anode wire to
remove it from the
shield.

Gently pull and twist the
shield to release the
anode wire from the
cable clamp.

Do not

Take Apart CRT Board (C Board) - 4

CRT Board (C Board)

Before you begin,

• Remove the rear cover

• Remove the EMI shield

• Discharge the CRT

±

CRT Board

(C 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 Board (C Board) - 5

1 Pull off the metal video

board shield.

Video Board Shield

Take Apart CRT Board (C Board) - 6

2 Remove the screw that

secures the black
ground wires to the video
color board frame.

3 Pull the CRT board

straight off the neck of
the CRT.

4

Caution:

Excessive force
might damage the video
board B connectors. If
the connectors are
difficult to remove, slip

Ground

Wires

a jeweler’s screwdriver
between the two halves
of the connector and
carefully pry them

CRT

Board

apart.

Take Apart CRT Board (C Board) - 7

Note:

Some connector

Video Board B

locations are different on
the Rev. A and Rev. B
versions of the CRT
board.

Disconnect the following
CRT board cable
connectors from video
board B:

• Gray, 1-wire cable

CRT Board

from B22

• White, 2-wire cable

from B15

• White, 4-wire cable

from B16

• Black, 2-wire cable

from B17

Take Apart CRT Board (C Board) - 8

• Yellow, 2-wire cable

Video Board B

from B18

• Red, 2-wire cable

from B19

CRT Board

Take Apart Video Color Board - 9

Video Color Board

Before you begin,

• Remove the rear cover

• Remove the EMI shield

• Discharge the CRT

• Remove the CRT board

±

Warning:

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.

Video Color Board

This product

Take Apart Video Color Board - 10

±

Video Color Board

(H Board)

Warning:

grounding wriststrap until
after discharging the CRT

Note:

The video color board
is an assembly composed of
three boards (H, B, and Q),
the metal frame that
supports the boards, and the
exterior I/O connector.

1 Remove the three screws

that secure the video
color board (H board) to
the metal chassis and
pull the board out
slightly.

Never use a

Take Apart Video Color Board - 11

2

Caution:

Excessive force
may pull the connector
off the board. If the
connector is difficult to
disconnect, slip a
jeweler’s screwdriver
between the two halves
of the connector and
carefully pry them
apart.

Disconnect the following
connectors from video
color boards B and H.

• Yellow, 3-wire cable

from H10

• White, 3-wire cable

from H14

Video Color Board

(H Board)

Video Color Board

(B Board)

Take Apart Video Color Board - 12

• Black, 3-wire cable

from H13

• Red, 3-wire cable

from H12

• White, 3-wire cable

from H11

• White, 3-wire cable

from B2

• Yellow, 4-wire cable

from B21

• Black, 4-wire cable

from B1

Video Color Board

(H Board)

Video Color Board

(B Board)

Take Apart Video Color Board - 13

3 Remove the five screws

that secure deflection
board D to the chassis.

4 Squeeze together the

plastic clamps and

Plastic Clamps

Deflection Board D

release the deflection
board. Squeeze the
clamps one at a time; if
necessary, use
needlenose pliers.

Take Apart Video Color Board - 14

Deflection Board D

5 Disconnect connectors

D-4 and D-5 from
deflection board D.

Note:

On the Rev. B
version of the deflection
board, the connectors
may begin with the
letter “B.”

Note:

Some connector
locations are different on
the Rev. A and Rev. B
versions of the video
color board.

Take Apart Video Color Board - 15

6 Remove the four screws

that secure the metal
frame of the video color
board to the chassis, and
remove the video color
board.

Video Color Board

Take Apart Deflection Board D, Rev. A - 16

Deflection Board D, Rev. A

Before you begin,

• Remove the rear cover

• Remove the EMI shield

• Discharge the CRT

±

Deflection Board D

(Rev. A)

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. Ê

This product

Never use a

Take Apart Deflection Board D, Rev. A - 17

1 Remove the five screws

that secure deflection
board D to the metal
chassis.

2 Squeeze together the

Plastic Clamps

plastic clamps and
release the deflection

Deflection Board D

board. Squeeze the
clamps one at a time; if
necessary, use
needlenose pliers.

3 Pull deflection board D

slightly away from the
chassis.

Take Apart Deflection Board D, Rev. A - 18

Deflection Board D

4 Disconnect these

connectors from the
deflection board:

• White, 3-wire cable

from D11

• White, 2-wire cable

from D9

• Yellow, 3-wire cable

from D10

• Black, 4-wire cable

from D1

• Black, 3-wire cable

from D13

• White, 3-wire cable

from D14

• White(lg), 4-wire

cable from D3

Take Apart Deflection Board D, Rev. A - 19

Deflection Board D

• Red, 4-wire cable

from D6

• White, 3-wire cable

from D2

• White, 4-wire cable

from D7

• Red, 3-wire cable

from D12

• White, 2-wire cable

from D5

• Gray, 1-wire cable

from D4

Take Apart Deflection Board D, Rev. A - 20

5 Peel back the rubber

High-Voltage

Capacitor Housing

boot on the flyback wire
in the high-voltage
capacitor housing. Insert
pliers into the opening
in the capacitor housing
and grasp the wire as
close as possible to the
capacitor. Push in
(toward the capacitor)

Flyback

Wire

and rotate the wire 1/4
turn counter­clockwise; then pull out
the wire.

6 Lift the deflection board

free.

Take Apart Deflection Board D, Rev. B - 21

Deflection Board D, Rev. B

Before you begin,

• Remove the rear cover

• Remove the EMI shield

• Discharge the CRT

• Disconnect anode cap

±

Warning:

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.

Deflection Board D

(Rev. B)

This product

Take Apart Deflection Board D, Rev. B - 22

±

Plastic Clamps

Warning:

grounding wriststrap until
after discharging the CRT.

1 Remove the five screws

that secure deflection
board D to the chassis.

Never use a

Deflection Board D

2 Squeeze together the

plastic clamps and
release the deflection
board. Squeeze the
clamps one at a time; if
necessary, use
needlenose pliers.

3 Pull deflection board D

slightly away from the
chassis.

Take Apart Deflection Board D, Rev. B - 23

Deflection Board D

4 Disconnect these cables

from the deflection
board:

• White, 3-wire cable

from D11

• White, 2-wire cable

from D9

• Yellow, 3-wire cable

from D10

• Black, 4-wire cable

from D1

• Black, 3-wire cable

from D13

• White, 3-wire cable

from D14

• White(lg), 4-wire

cable from D3

Take Apart Deflection Board D, Rev. B - 24

Deflection Board D

• White, 3-wire cable

from D2

• White, 4-wire cable

from D7

• Red, 3-wire cable

from D12

• White, 2-wire cable

from D5

• Gray, 1-wire cable

from D4

Take Apart Deflection Board D, Rev. B - 25

5 Remove the wires from

Deflection Board

the cable clamp.

Cable Clamp

6 Lift the deflection board

free.

Cable Wires

Take Apart Power Supply - 26

Power Supply

Before you begin,

Power Supply

• Remove the rear cover

• Remove the EMI shield

• Discharge the CRT

±

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 Power Supply - 27

1 Remove the four

mounting screws and
slide the power supply
back slightly.

Power Supply

Take Apart Power Supply - 28

2 Disconnect the large

two-wire connector
from the top of the
power supply, and the
small four-wire
connector from the
front of the power
supply.

3 Slide the power supply

back and out of the
chassis.

Take Apart Fuses - 29

Fuses

Before you begin,

• Remove the rear cover

• Remove the EMI shield

Fuses

• Discharge the CRT

• Remove the power supply

±

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 Fuses - 30

1 Remove the top screw

and washer and the end
screw from the power
supply cover. Lift off the
cover.

Power Supply

Take Apart Fuses - 31

2 Remove a blown fuse by

prying up one end of the
fuse with your fingers
or a small flat-blade
screwdriver.

Note:

There are two fuses in
the power supply, F101
(6.3A/250V) and F102
(3.15A/250V). These fuses
are not interchangeable.

Take Apart Contrast Control Board J - 32

Contrast Control Board J

Before you begin,

• Remove the rear cover

• Discharge the CRT

±

Warning: This product

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in

Contrast Control Board J

Bulletins/Safety.

±Warning: Never use a

grounding wriststrap until
after discharging the CRT.

Take Apart Contrast Control Board J - 33

1 Disconnect the yellow 4-

wire cable from
connector J-21, and the
white 2-wire cable from
connector J-8.

Take Apart Contrast Control Board J - 34

2 Pull off the two knobs,

and remove the two
mounting screws and the
contrast control board.

Replacement Note: Save
the knobs to put on the
replacement board.

Take Apart High-Voltage Capacitor - 35

High-Voltage Capacitor

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Disconnect anode cap

±Warning: This product

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.

±Warning: Never use a

grounding wriststrap until
after discharging the CRT.

High-Voltage Capacitor

Take Apart High-Voltage Capacitor - 36

1 Remove the four screws

that secure the metal
screen to the bottom of
the chassis.

2 Tip out the metal screen

and the attached high­voltage capacitor.

Take Apart High-Voltage Capacitor - 37

High-Voltage

Capacitor Housing

Flyback

Wire

3 Peel back the flyback

wire’s rubber boot
from the opening in the
high-voltage capacitor
housing. Insert pliers
into the opening in the
capacitor housing and
grasp the wire as close
as possible to the
capacitor. Push in
(toward the capacitor)
and rotate the wire 1/4
turn counter­clockwise; then pull out
the wire.

Take Apart High-Voltage Capacitor - 38

Deflection Board D

4 Disconnect the gray wire

from its red 4-wire
connector at D-6 on the
deflection board.

Take Apart High-Voltage Capacitor - 39

5 Lift off the metal screen

High-Voltage

Capacitor

with attached high­voltage capacitor.

6 Remove the two

mounting screws and the
high-voltage capacitor
from the screen.

Take Apart Chassis - 40

Chassis

Chassis

Before you begin,

• Remove the rear cover

• Remove the EMI shield

• Discharge CRT

• Disconnect anode cap

±Warning: This product

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.

±Warning: Never use a

grounding wriststrap until
after discharging the CRT.

Take Apart Chassis - 41

Deflection Board D

Note: The chassis is not a
replaceable part. Perform
this procedure to access the
CRT or the LED.

1 Disconnect the white 2-

wire connector from D3
and the white 4-wire
connector from D9 on
deflection board D.

Note: On the Rev. B
version of the deflection
board the connectors
may begin with the
letter “B.”

Take Apart Chassis - 42

2 Disconnect the white 2-

wire connector from the
contrast control board
J8.

3 Remove the wires from

the plastic cable clamps.

Take Apart Chassis - 43

4 Pull the CRT board

straight off the neck of

CRT Board

the CRT.

5 Remove the four corner

screws that secure the
metal chassis to the
bezel. Lift off the chassis
with attached modules.

Chassis

Take Apart CRT Assembly - 44

CRT Assembly

Before you begin,

• Remove the rear cover

• Remove the EMI shield

• Discharge the CRT

• Disconnect the anode cap

• Remove the chassis

±Warning: This product

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.

CRT Assembly

Take Apart CRT Assembly - 45

±Warning: Never use a

grounding wriststrap until
after discharging the CRT.

±Warning: If the CRT is

cracked or damaged, refer
to the CRT safety and
disposal instructions in
Bulletins/Safety.

Caution: The neck of the CRT
is easily damaged. Do not
grab the neck of the CRT to
remove it from the bezel.

Support the side of the CRT
with one hand, tip the bezel
to one side, and carefully
ease the CRT out of the bezel.

Take Apart LED - 46

LED

Before you begin,

• Remove the rear cover

• Remove the EMI shield

• Discharge CRT

• Remove the anode cap

• Remove the chassis

±Warning: This product

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.

LED

Take Apart LED - 47

Front Bezel

±Warning: Never use a

grounding wriststrap until
after discharging the CRT.

Remove the screw that
secures the LED cable
assembly to the front bezel.
Lift out the LED.

LED Cable Assembly

K

Service Source

Adjustments

AppleColor High-Resolution

RGB Monitor

Adjustments Geometry - 1

Geometry

No preliminary steps are
required before you begin
this procedure.

Note:

Perform the geometry
adjustments in order.
Although the geometry
controls are shown here
with the rear cover
removed, you can access
them from the service
access panel at the rear of
the monitor.

Brightness

and Contrast

Knobs

Geometry Controls

Adjustments Geometry - 2

±

Warning:

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.

This product

Caution:

yoke adjustments on this
monitor. All such
adjustments have been set
by the manufacturer.

Do not attempt

Adjustments Geometry - 3

Horizontal Size

Note:

Due to video features
and timing differences
across the Apple line of
Macintosh computers, the
width of the raster/image
area on the Hi-Res RGB
monitor may vary up to 3/
16 inch at each side of the
display. Perform the
horizontal size adjustment
to set the display to its
proper width.

1 Use Display Service

Utility to display the
All-White Screen test
pattern.

Adjustments Geometry - 4

2 Using a plastic

screwdriver, adjust the
horizontal size control
until the raster width is
9 1/4 in. (± 1/8 in.) or
235 mm (± 2 mm).

Adjustments Geometry - 5

Vertical Size

Note:

Adjust the horizontal
size before you adjust the
vertical size. The horizontal
adjustment can affect the
height of the raster.

1 Use Display Service

Utility to display the
Crosshatch II (white
background) test
pattern.

2 Using a plastic

screwdriver, adjust the
vertical-size control
until the raster height is
7 in. (± 1/8 in.) or 176

Adjustments Geometry - 6

mm (± 2 mm).

Adjustments Geometry - 7

Focus

1 Use Display Service

Utility to display the
Focus test pattern.

2 Using a plastic

screwdriver, adjust the
focus control for the best
clarity at points
halfway between the
center and the left and
right edges of the screen.

Adjustments Video - 8

Video

Before you begin, remove
the following:

• Rear cover

• EMI shield

• Video board shield

±

Brightness

Knobs

and Contrast

Video Color Board

(H Board)

CRT Board
(C Board)

Video
Color

Board

(B Board)

Warning:

contains high voltage and a
high-vacuum picture tube.
To prevent serious injury,
review CRT safety in
Bulletins/Safety.

This product

Adjustments Video - 9

±

Warning:

make adjustments from the
rear of the computer,
position a mirror to view
the computer screen. Do not
reach around the computer
to adjust the controls.

Note:

Perform the cutoff
adjustment whenever you
replace the CRT assembly,
deflection board D, or the
video color board.

Because you

Adjustments Video - 10

1 Remove the video cable

from the back of the
monitor. Switch on the
monitor.

Note:

Perform the
cutoff and white balance
adjustments in a dimly
lit room after the
monitor has been on for
at least 10 minutes.

Brightness

2 Set the external (user)

contrast knob to
maximum and the
external brightness
knob to the center
(detent) position.

Contrast

Adjustments Video - 11

Video Color Board (B Board)

Video Color Board (H Board)

SUB BRT SUB CONT

Cutoff

1 Using the plastic

screwdriver, adjust the
following controls on
the video color board (B
board) to midrange:

• B.BKG (R.BKG on Rev.

B version)

• G.BKG

• R.BKG (B.BKG on Rev.

B version)

• R.DRIVE

• G.DRIVE

• B.DRIVE

• SUB CONT

• SUB BRT

Adjustments Video - 12

2 Set the voltmeter to

measure 140 volts DC.

3 Attach the voltmeter

ground lead (black lead)
to the monitor chassis.

4 Connect the voltmeter

red lead to the cathode
marked KR on the CRT

CRT Board

(C Board)

board (C board).
Gradually adjust the
R.BKG control until the
voltage measures 140 V
(± 2 V).

Adjustments Video - 13

5 Connect the voltmeter

red lead to the pin
marked KG on the CRT
board (C board).
Gradually adjust the
G.BKG control until the
voltage measures 140 V
(± 2 V).

CRT Board
(C Board)

Adjustments Video - 14

6 Connect the voltmeter

red lead to the pin
marked KB on the CRT
board (C board).
Gradually adjust the
B.BKG control until the
voltage measures 140 V
(± 2 V).

CRT Board

(C Board)

Adjustments Video - 15

7

Note:

If you increase the
cutoff control

Video Color Board (B Board)

Video Color Board

(H Board)

(clockwise) too far, the
monitor might shut
down. If this happens,
switch off the monitor

Cutoff

and turn the cutoff
control all the way down
(counterclockwise).
Wait 30 seconds, switch
on the monitor, and
resume the adjustment.

Using a plastic
screwdriver, adjust the

SUB BRT

cutoff control until the
raster is just visible.

Adjustments Video - 16

8 Turn the cutoff control

counterclockwise until

Video Color Board (B Board)

Video Color Board

(H Board)

the raster just
disappears.

Caution:

Once the cutoff

control on the video

Cutoff

color board (H board) is
correct, do not move it
again unless you repeat
the cutoff adjustment.
The life of the picture
tube decreases severely
if the cutoff adjustment
is incorrect.

SUB BRT

Adjustments Video - 17

White Balance

Video Color Board

(H Board)

Cutoff

Video Color Board (B Board)

Caution:

cutoff is correct before you
proceed. The life of the
picture tube decreases
severely if the cutoff
adjustment is incorrect.

1 Switch off the monitor,

2 Use Display Service

Make sure the

connect the video cable,
and switch the monitor
back on.

Utility to display the
Gray Bars test pattern.

Adjustments Video - 18

3 Using the plastic

screwdriver,
alternately adjust the
B.BKG, G.BKG, and R.BKG

Video Color Board

Video Color Board (B Board)

(H Board)

B.BKG

controls until

• The left (dark) three

bars have no colored
tint

• The leftmost bar is as

black as the screen
border

• You can barely

distinguish the second
bar from the black bar

G.BKG

• The third bar is a

dark gray

Note:

R.BKG

To achieve good

Adjustments Video - 19

color balance, try
reducing the background
of the predominant color.
If necessary, increase
the other background
controls until you see no
color tint.

4

Important:

from light meter models
R77, L-248, and 246
differ. Please note
which meter you are
using before making
adjustments. (See
“Light Meter Setup.”)

Using the light meter and
a two-inch plastic

Readings

Adjustments Video - 20

H Board

B Board

G.DRIVE

Light Meter

screwdriver, adjust the
G.DRIVE control until the
luminance of the
rightmost (brightest)
bar measures 24 foot
lamberts (± 3 foot
lamberts), which on the
light meter is

• Model R77: 19 on the

bottom scale

• Model L-248: 9 to 10

on the 2-10 scale

• Model 246: 19 on the

red scale

Important:

Over time,
light meter tolerances
can vary. If you doubt

Adjustments Video - 21

your meter’s accuracy,
verify the readings with
a known-good light
meter or photometer.

B Board

5 Adjust the R.DRIVE and

H Board

B.DRIVE until you see no
predominant color in
the three right
(brightest) bars.

6 As necessary, repeat the

G.DRIVE, R.DRIVE, and
B.DRIVE adjustments.

R.DRIVE

G.DRIVE

B.DRIVE

Adjustments Video - 22

7 If the left (darkest) bars

now show a predominant
color, readjust the
background controls

B Board

H Board

B.BKG

(B.BKG, G.BKG, and
R.BKG) of the two
nonpredominant colors
until you see only
shades of black and gray.

Note:

The white balance

is correct if

• You see no

predominant color

G.BKG

• The brightest bar

measures 24 foot

SUB CONTSUB BRT

R.BKG

lamberts (± 3 foot
lamberts) or 9 to 10

Adjustments Video - 23

on light meter Model
L-248 or 19 on light
meter Model 246 or
19 on light meter
Model R77

• The left (darkest)

bars are black,
barely
distinguishable, and
dark gray.

If you desire additional
fine tuning, adjust the
sub-contrast and sub­brightness controls in
the next steps.

Adjustments Video - 24

Sub-Contrast

Adjust the SUB CONT
control so that the

B Board

H Board

SUB CONT

luminance in the middle of
the rightmost (brightest)
bar measures 24 foot
lamberts (± 3 foot
lamberts), which is

• Model L-248: middle of
the 9 scale

• Model 246: 19 on the red
scale

• Model R77: 19 on the
bottom scale

Adjustments Video - 25

Important:

meter tolerances can vary.
If you doubt your meter’s
accuracy, verify the
readings with a known-good
light meter or photometer.

Over time, light

Adjustments Video - 26

Sub-Brightness

Adjust the SUB BRT control
so that the leftmost bar is

B Board

H Board

SUB BRT

completely black and the
next bar is barely
distinguishable from the
black bar.

Adjustments Light Meter Setup - 27

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 - 28

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 - 29

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 - 30

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 - 31

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 lower position so that
the scale reads 2 through

10.

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.