Apple 12 Rgb Display Service Manual

K

Service Source

Macintosh 12 RGB Display

K

Service Source

Specifications

Macintosh 12" RGB Display

Specifications Characteristics - 1

Characteristics

Picture Tube

Screen Resolution

Scan Rates

12-in. viewable diagonal screen
90° deflection angle; black matrix-type dot screen
Phosphor type P22 (aluminized)
Spherical, antiglare surface

512x384 lines; 64 dpi
Displays up to 256 colors with Macintosh Display Card 4•8 and

16.7 million colors with Macintosh Display Card 8•24

Vertical refresh rate: 60.15 Hz
Horizontal scan rate: 24.48 kHz
Rise and fall time: 27 ns maximum

Specifications Characteristics - 2

Active V ideo Display Area

Input Signals

8.08 in. by 6.02 in. (205 mm by 153 mm)

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

Specifications Controls - 3

Controls

User Controls

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

Specifications Physical and Electrical - 4

Physical and Electrical

Power Supply (International)

Power Supply (Domestic)

Size and Weight

Universal power supply
Voltage: 90–270 VAC, self-configuring
Frequency: 47–63 Hz, single-phase
Power: 90 W maximum

Voltage: 100–120 VAC
Frequency: 50–60 Hz
Power: 90 W maximum

Height: 12.2 in. (310 mm)
Width: 14.4 in. (365 mm)
Depth: 10.0 in. (253 mm)
Weight: 35 lb. (15.9 kg)

Specifications Operating Environment - 5

Operating Environment

Temperature

Humidity

Altitude

50°F–104°F (10°C–40°C)

95% maximum, noncondensing

10,000 ft. (3,048 m) maximum
104°F (40°C) operation from 0–7000 ft. (2,134 m) and derated

linearly to maximum 64°F (25°C) at 10,000 ft.

K

Service Source

Troubleshooting

Macintosh 12" RGB Display

Troubleshooting General - 1

General

The Symptom Charts included in this chapter will help you
diagnose specific symptoms related to your product. Because cures
are listed on the charts in the order of most likely solution, try
the first cure first. Verify whether or not the product continues to
exhibit the symptom. If the symptom persists, try the next cure.
(Note: If you have replaced a module, reinstall the original module
before you proceed to the next cure.)

If you are not sure what the problem is, or if the Symptom Charts
do not resolve the problem, refer to the Flowchart for the product
family.

For additional assistance, contact Apple Technical Support.

Troubleshooting Symptom Charts/No Raster - 2

Symptom Charts

No Raster

No raster, LED off 1 Ensure monitor’s video cable is connected to the computer or

the video card in the computer.
2 Check power cord.
3 Check internal power connectors.
4 Replace blown fuse.
5 Replace external power cable assembly.
6 Replace main deflection board.

No raster, LED on 1 Ensure monitor’s video cable is connected to the computer or

the video card in the computer.
2 Adjust contrast and brightness user controls.
3 Verify that video card in monitor is working properly.
4 Check main deflection board and CRT/video board connectors.
5 Replace blown fuse.
6 Perform screen adjustment.
7 Replace main deflection board.
8 Replace CRT/video board.
9 Replace CRT.

Troubleshooting Symptom Charts/Geometry - 3

Geometry

Raster size short/
tall, narrow/wide

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

Horizontal linearity
bad (screen sides
differ)

1 Adjust V-HEIGHT or H-WIDTH controls on main deflection

board.
2 Replace main deflection board.
3 Replace CRT.

Move monitor to another location.
2 Adjust H-CENT or V-CENT external controls.
3 Replace main deflection board.

Replace main deflection board.

Troubleshooting Symptom Charts/Geometry

(Continued)

- 4

Geometry

Vertical linearity bad
(screen top and
bottom differ)

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

1 Adjust V-LIN control on main deflection board.
2 Replace main deflection board.

Move monitor to another location.
2 Check V-HEIGHT and V-CENT adjustment controls and H-

WIDTH and H-CENT controls. (Some bowing from

environmental conditions is normal and is within

manufacturing tolerances. Slight bowing does not impair

functionality of monitor.)
3 Replace main deflection board.
4 Replace CRT.

(Continued)

Troubleshooting Symptom Charts/Geometry

(Continued)

- 5

Geometry

Entire raster is tilted 1 Verify that distortion is not due to environmental conditions.

Move monitor to another location.
2 Adjust yoke assembly as follows:

• Switch off power and remove rear cover

• Loosen frontmost screw on neck of CRT

• Twist yoke assembly as appropriate

• Retighten screw on neck of CRT (Do not overtighten screw;

• Switch on monitor and check display

3 Replace main deflection board.

(Continued)

you could break neck of CRT.)

Troubleshooting Symptom Charts/Geometry

(Continued)

- 6

Abnormal/distorted
raster (other than
above)

Geometry

1 Verify that distortion is not due to environmental conditions.

Move monitor to another location.
2 Check all cable connections.
3 Perform geometric adjustments.
4 Replace main deflection board.
5 Replace CRT/video board.
6 Replace CRT.

(Continued)

Troubleshooting Symptom Charts/Synchronization - 7

Synchronization

Picture breaks into
diagonal lines

Picture rolls
vertically

Single vertical or
horizontal line on
screen

1 Connect another monitor to computer and verify video signal.
2 Adjust H-HOLD control on main deflection board.
3 Replace main deflection board.

1 Verify that video card in monitor is working properly.
2 Adjust V-HOLD control on main deflection board.
3 Replace main deflection board.

1 Check yoke connector DY.
2 Replace main deflection board.
3 Replace CRT.

Troubleshooting Symptom Charts/Video - 8

Video

Predominant red,
blue, or green tint

Picture too dark or
too bright

1 Check video cable connection.
2 Verify that video card in monitor is working properly.
3 Perform white balance adjustments.
4 Replace CRT/video board.
5 Replace CRT.

1 Adjust contrast and brightness knobs.
2 Verify that video card in monitor is working properly.
3 Perform video adjustments (cutoff and white balance).
4 Replace main deflection board.
5 Replace CRT/video board.
6 Replace CRT.

Troubleshooting Symptom Charts/Video

(Continued)

- 9

Video

Cannot adjust
brightness, contrast,
or color

Out of focus 1 Adjust focus control on flyback transformer.

1 Replace contrast/brightness assembly.
2 Replace main deflection board.
3 Replace CRT/video board.

2 Perform screen adjustment.
3 Replace main deflection board.
4 Replace CRT.

(Continued)

Troubleshooting Symptom Charts/Miscellaneous - 10

Miscellaneous

Intermittently shuts
down

Picture jitters or
flashes

Flashing or wavy
screen

Black spots on screen
(burnt phosphors)

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

the video card in the computer.
2 Replace main deflection board.

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

grounded. Move other electrical devices away from monitor.

Shut off fluorescent lights.
3 Replace main deflection board.

1 Crimp metal connector tabs on video connector.
2 Replace main deflection board.

Replace CRT.

K

Service Source

T ak e Apart

Macintosh 12" RGB Display

Take Apart Rear Cover - 1

Rear Cover

No preliminary steps are
required before you begin
this procedure.

±

Rear Cover

Warning:

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

This product

Take Apart Rear Cover - 2

1 Place the monitor face-

down on a protective pad
and remove the two case
screws.

2 Separate the bottom of

the rear cover from the
bezel.

Take Apart Rear Cover - 3

3 Set the monitor upright.

4 Press down about one

inch from the outside
edges of the bezel to
separate the top of the
rear cover from the
bezel.

Take Apart Rear Cover - 4

5 Place the monitor face-

down on a protective pad.

6 Lift off the loosened

rear cover.

7 Pull the AC power cord

and video cable through
the cover.

Take Apart Contrast/Brightness Assembly - 5

Contrast/ Brightness Assembly

Contrast/Brightness

Assembly

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

±

Warning:

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

±

Warning:

This product

Never use a

Take Apart Contrast/Brightness Assembly - 6

grounding wriststrap until
after discharging the CRT.

J204

1 Disconnect the six-wire

cable from connector
J204 on the CRT/video

Cable Retainer

board. Remove the six
wires from the cable
retainer.

Mounting Bracket

2 Remove brightness

VR204

board VR204 and
contrast board VR203
from the mounting

VR203

bracket.

3 Unhook and pull the six

wires through the back
of the mounting bracket.

Take Apart Contrast/Brightness Assembly - 7

4 Pull off the two control

knobs.

5 Disconnect cable

J206

connector J206 from the
brightness board and
cable connector J205

Brightness Board - VR204

Plastic Control Knobs

J205

from the contrast board.

Contrast Board

VR203

Take Apart Fuse - 8

Fuse

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

±

Fuse

Warning:

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

±

Warning:

grounding wriststrap until
after discharging the CRT.

This product

Never use a

Take Apart Fuse - 9

Using a small flat-blade
screwdriver, pry the
defective fuse from
connector F901 on the
deflection board.

F901

Take Apart CRT/Video Board - 10

CRT/Video Board

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

±

CRT/Video Board

Warning:

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

±

Warning:

grounding wriststrap until
after discharging the CRT.

This product

Never use a

Take Apart CRT/Video Board - 11

1 Remove the screw that

secures the video cable
to the cable clamp at the
back of the CRT/video
board.

2 Remove the video cable

from the clamp and
remove the clamp from
the CRT/video board.

Take Apart CRT/Video Board - 12

J203

SC

J204

J201

J202

3 Disconnect the following

cable connectors from
the CRT/video board:

• 6-wire cable from
J204

• 8-wire video cable
from J201

• Single-pin cable from
SC

• 5-wire, 7-pin cable
from J202

• 6-wire, 8-pin cable
from J203

Take Apart CRT/Video Board - 13

4

Note:

To unhook the CRT

ground cable, you must

Plastic Locking Nut

first press the small
metal catch in the
center of the connector.

Disconnect the CRT
ground cable from

Cable Retainer

connector PIN 1 on the
CRT/video board.

5 Remove the two cables

from the cable retainer
on the main deflection
board beneath the neck of
the CRT.

Pin 1

Take Apart CRT/Video Board - 14

6 Loosen (turn clockwise,

as viewed from the rear

Plastic Locking Nut

of the monitor) the
plastic locking nut on the
neck of the CRT.

Cable Retainer

Pin 1

Take Apart CRT/Video Board - 15

Note:

To remove the CRT/
video board over the rear
metal chassis, tilt the CRT
assembly slightly.

7 Grasp the back of the

CRT/video board with

CRT/Video Board

both hands and pull the
board straight back off
the neck of the CRT. Note
that a cable still
connects the CRT/video
board to the flyback
transformer.

Take Apart CRT/Video Board - 16

8 Place the CRT/video

board on the protective
mat next to the flyback
transformer.

9 Unfasten the two side

tabs and open the white
plastic cover over

Q201

connector Q201. You
may need to use a small
flat-blade screwdriver
to open the tabs.

Take Apart CRT/Video Board - 17

10

Caution:

To avoid
damaging the CRT/video
board, use a low-wattage
soldering iron. Touch
only the connector Q201
terminal with the
soldering iron.

Q201

Desolder the flyback
transformer cable from
connector Q201.

Take Apart External Power Cable - 18

External Power Cable

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

±

External Power Cable

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 External Power Cable - 19

Note:

The international
version of the 12” RGB
display has a detachable
external power cable.

1 Disconnect the two-

wire, three-pin power
connector from the AC

AC Connector

connector on the main
deflection board.

Take Apart External Power Cable - 20

2 Using a 9/32-inch hex

driver or a small
adjustable wrench,
remove the hex screw
that secures the AC
ground cable to the rear
of the metal chassis.

Take Apart External Power Cable - 21

3 R emove the two screws

that secure the power
cable to the metal
chassis.

4 Remove the power cable.

Take Apart CPU-to-Monitor Cable - 22

CPU-to-Monitor Cable

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

±

CPU-to-Monitor Cable

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 CPU-to-Monitor Cable - 23

1 Disconnect the eight-

CRT/Video Board

wire video connector
from connector J201 on
the CRT/video board.

J201

Take Apart CPU-to-Monitor Cable - 24

2 R emove the screw that

secures the video cable
to the back of the CRT/
video board.

Remove the video cable
from the cable clamp.

Video Cable

Take Apart CPU-to-Monitor Cable - 25

3 Remove the screw that

secures the video cable
to the mounting bracket
on the rear chassis.

Remove the video cable
from the cable clamp.

Take Apart CPU-to-Monitor Cable - 26

4 Remove the two screws

that secure the video
cable to the metal
chassis.

5 Remove the video cable

from the chassis.

Take Apart Main Deflection Board - 27

Main Deflection Board

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

• Remove the CRT/video

board

• Remove the external

power cable

• Remove the CPU-to-

monitor cable

Main Deflection

Board

Take Apart Main Deflection Board - 28

±

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 Main Deflection Board - 29

1 Disconnect the following

cable connectors from
the main deflection
board:

• 2-wire cable from PC

• 2-wire LED cable
from J502 (Detach
the LED cable from
the back of the

DY

flyback transformer.)

• 4-wire yoke cable
from DY

PC

J502

Take Apart Main Deflection Board - 30

2 R emove the screw that

secures the two internal
ground cables to the
metal chassis.

3 Remove all cables from

the cable retainer on the
main deflection board.

Cable Retainer

Take Apart Main Deflection Board - 31

4 Remove the two screws

that secure the flyback
transformer to the right
stem of the plastic main
deflection board holder.

5 Remove the two screws

that secure the rear
chassis to the end of both
stems of the plastic main
deflection board holder.

Flyback
Transformer

Take Apart Main Deflection Board - 32

6 Pull the main deflection

board straight out of the
channels in the plastic
main deflection board
holder.

Replacement Note:

and Rev. B versions of the
main deflection board are
not interchangeable and
must be replaced like-for­like.

Rev. A

Take Apart Main Deflection Board - 33

To differentiate between
versions, look for a gray
coil (VR504) next to
connector J502 and do the
following:

• If the bad board does not
have coil VR504, order a
Rev. A main deflection
board.

• If the bad board has coil
VR504, order a Rev. B
main deflection board.

VR504

J502 Connector

Take Apart Main Deflection Board Holder - 34

Main Deflection Board Holder

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

• Remove the CRT/video
board

• Remove the main
deflection board

±

Main Deflection Board Holder

Warning:

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

This product

Take Apart Main Deflection Board Holder - 35

±

Warning:

grounding wriststrap until
after discharging the CRT.

1 With the monitor face-

down on a protective pad,
lift and pull the left and
right front edges of the
main deflection board
holder to remove it
from the bezel.

Never use a

Take Apart Main Deflection Board Holder - 36

2 R emove the mounting

screw and the contrast/
brightness assembly
from the main deflection
board holder.

Contrast/Brightness

Assembly

Take Apart CRT Assembly - 37

CRT Assembly

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

CRT Assembly

• Remove the CRT/video
board

• Remove the main
deflection board

• Remove the main board
holder

Take Apart CRT Assembly - 38

±

Warning:

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

This product

±Warning: Never use a

grounding wriststrap until
after discharging the CRT.

Take Apart CRT Assembly - 39

1 Caution: The neck of the

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

Remove the four
mounting screws and
carefully lift the CRT
from the bezel. Place
the CRT face-down on the
protective pad.

Take Apart CRT Assembly - 40

2 Remove the four spacers

from the plastic
standoffs at the corners
of the bezel.

Take Apart CRT Assembly - 41

Revision A

Revision B

J502

Main Deflection
Board

Replacement Note: If you
are replacing the CRT, you
must order a replacement
CRT that is compatible with
the main deflection board in
the customer’s system.

Check the main deflection
board for resistor VR504.

• If VR504 is not present,
you have a Rev. A main
board. Order Standard
CRT 076-0384.

• If VR504 is present, you
have a Rev. B main board.
Order Low ELF CRT 076-

0395.

Take Apart CRT Assembly - 42

Replacement Note: CRTs

Field Coil

ship in Standard and Low
ELF versions. Yoke boards
come in many variations. To
determine whether the CRT

Standard

CRT

Low ELF

CRT

is a Standard or Low ELF
CRT, check for field coils.
The Low ELF CRT has two
field coils, one on top and one
on the bottom of the CRT. The

Yoke Board

Standard CRT does not have
field coils.

Replacement Note: After
replacing a defective CRT,
perform the voltage
adjustment procedure (see
Adjustments).

Take Apart LED Assembly Cable - 43

LED Assembly Cable

Before you begin,

• Remove the rear cover

• Discharge the CRT

• Remove the anode cap

• Remove the CRT/video
board

• Remove the main
deflection board

• Remove the main board
holder

• Remove the CRT assembly

LED Assembly

Cable

Take Apart LED Assembly Cable - 44

LED Assembly

PC

±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.

1 Remove the black

degauss cable from the
bezel. Connector PC is
attached to the cable.

2 Remove the mounting

screw and the LED
assembly from the bezel.

Take Apart Bezel - 45

Bezel

To remove the bezel,

• Remove the rear cover

• Discharge the CRT

Bezel

• Remove the anode cap

• Remove the CRT/video
board

• Remove the main
deflection board

• Remove the main board
holder

• Remove the CRT assembly

• Remove the LED assembly

Take Apart Bezel - 46

±Warning: This product

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

K

Service Source

Adjustments

Macintosh 12 RGB Display

Adjustments Screen Voltage - 1

Screen Voltage

Before you begin, remove
the cover.

±

Warning:

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

This product

Adjustments Screen Voltage - 2

±

Warning:

adjustments are made 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:

If you have replaced
the main deflection board,
you must perform the
screen adjustments prior to
performing other
adjustments. If you have not
replaced the main deflection
board, go to the Geometry
adjustments.

Because

Adjustments Screen Voltage - 3

Note:

The look and operation
of buttons and jacks on
voltmeters vary.

Note:

Perform the screen
voltage adjustment only if
one or more of the following
conditions apply:

• You have replaced the

main deflection board.

Voltmeter

• You have inadvertently

altered the screen
adjustment.

• You have replaced the

High-Voltage Probe

CRT/yoke assembly with
a different revision CRT/
yoke assembly.

Adjustments Screen Voltage - 4

Note:

Performing the
screen voltage adjustment
requires a voltmeter and a
high-voltage probe (Apple
service part number 076-

0392).

1

Caution:

voltage probe other than
Apple part number
076-0392 could damage
the monitor.

Use only a high-voltage
probe that meets these
specifications:

• 40 KV (VDC) rating

• Input impedance of
1000 megohms

Using a high-

Adjustments Screen Voltage - 5

• Banana clips to plug
into a voltmeter

• Alligator clip to

2 VDC Setting

connect to ground

2 Switch on the voltmeter

power and set the

Power

voltmeter to the 2 VDC
(or lowest) setting.

High-Voltage Probe

Adjustments Screen Voltage - 6

3 Connect the high-

voltage probe two­pronged connector to the
ground and voltage
receptacles on the
voltmeter.

Make sure the prong
with the ground tab is in
the ground receptacle.

Adjustments Screen Voltage - 7

4 Switch on the monitor

and let it warm up for at
least 10 minutes.

5 Attach the ground clip

from the high-voltage
probe to the metal
chassis.

Adjustments Screen Voltage - 8

6 Set the contrast knob to

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

Adjustments Screen Voltage - 9

7 Use Display Service

Utility to display the
Full Black Screen test
pattern.

SUB-BRIGHT

Control

Full Black Screen

8 Turn the SUB-BRIGHT

control (VR202) all the
way down
(counterclockwise).

Adjustments Screen Voltage - 10

9 To set the screen voltage,

first check the label on
the side of the CRT to
determine the type: CRT
type AT12A9SL or CRT
type M29JMN097X13.

Label

10±Warning:

Because
you must measure
voltages in excess of 500
volts DC, make sure the
high-voltage probe is
grounded to the metal
monitor chassis. Do not
short the probe between
the test point and
adjacent components.

Adjustments Screen Voltage - 11

Touch the high-voltage

PIN 4

probe to the voltage test
point labeled SCREEN
(U.S. version) or PIN 4
(international version).

SCREEN

High-Voltage

Probe

11 Adjust the screen control

until the voltmeter
reads:

• 500 V (± .005 V) for

CRT AT12A9SLB

• 400 V (± .004 V) for

CRT M29JMN097X13

Screen
Control

Adjustments Screen Voltage - 12

12 Disconnect the high-

voltage probe from the
monitor.

13 Press the space bar or

Gray Bars

click the mouse to
advance to the next test
pattern. Turn the SUB­BRIGHT control
(VR202) until the

SUB-BRIGHT

Control

raster is visible.

14 Use Display Service

Utility to display the
Gray Bars test pattern.

Adjustments Screen Voltage - 13

15 Adjust the SUB-BRIGHT

control until the first
bar is black and the
second bar is barely

Gray Bars

SUB-BRIGHT

Control

visible.

Adjustments Screen Voltage - 14

SUB-CONTRAST

Control

All-White Screen

Important:

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

16 Using Display Service

Utility, display the All­White Screen test
pattern.

17 Using the light meter and

a two-inch plastic
screwdriver, adjust the
SUB-CONTRAST control
(VR201) until you get
the following:

Adjustments Screen Voltage - 15

• Model 248: top of the
10 scale

• Model 246: 30 ft.
lamberts (± 3 ft.

All-White Screen

lamberts)

Note:

If you are unable
to adjust the SUB­CONTRAST control to get
the correct reading,

SUB-CONTRAST

Control

perform the White
Balance video
adjustment.

Adjustments Geometry - 16

Geometry

Before you begin, remove
the cover.

±

Geometry

Adjustment

Controls

Warning:

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

±

Warning:

adjustments are made from
the rear of the computer,
position a mirror to view
the computer screen. Do not

This product

Because

Adjustments Geometry - 17

reach around the computer
to adjust the yoke.

Note:

Geometry adjustments
may be necessary whenever
you replace the main
deflection board, CRT, or
video board.

Note:

Do not attempt yoke
adjustments on this monitor.
The factory settings require
no adjustment.

Adjustments Geometry - 18

Vertical Size

Note:

Vertical size, vertical

center, and horizontal

All-White Screen

V-HEIGHT

Control

center adjustments can be
performed without
removing the rear cover.

1 Use Display Service

Utility to display the
All-White Screen test
pattern.

2 Adjust the V-HEIGHT

control (VR404) with a
plastic screwdriver
until the raster height is
153 mm (± 2 mm) or 6
1/16 in. (± 1/16 in.).

Adjustments Geometry - 19

Vertical Center

1 Using a plastic

screwdriver, adjust the
V-CENT control
(VR403) until the
raster is centered (top
to bottom) in the
display area.

2 Verify that the raster

height is 6 1/16 in. (±
1/16 in.) or 153 mm
(± 2 mm). If it is not,
repeat the Vertical Size
adjustment and, if
necessary, the Vertical

V-CENT Control

Center adjustment.

Adjustments Geometry - 20

Horizontal Center

Using the plastic
screwdriver, adjust the H­CENT control (VR503) until
the raster is centered (side
to side) in the display area.

Note:

If you cannot center
the raster, set the H-CENT
control at midrange and
perform the following steps.

H-CENT Control

Adjustments Geometry - 21

Note:

Perform the following
steps only if you could not
center the raster using the
V-CENT and H-CENT
controls.

1 Switch off the monitor

and remove the rear
cover. See “Rear
Cover” in the Take Apart
chapter.

2 Switch on the monitor.

H-PHASE

Control

Adjustments Geometry - 22

3 Using the plastic

screwdriver, adjust the
H-PHASE control
(VR501) until the
raster is positioned at
the visual midpoint of
the range of the H­PHASE control.

Note:

You may need to
check the limits of the
H-PHASE control to find
its midpoint.

H-PHASE

Control

Adjustments Geometry - 23

4 Using the plastic

screwdriver, adjust the
H-CENT control
(VR503) until the
raster is in the
approximate center of
the screen.

H-CENT

Control

Adjustments Geometry - 24

Horizontal Size

H-WIDTH

Control

Before yu begin,

rear cover.

Using the hex-head insulated
adjustment tool, adjust the
H-WIDTH control (L501)
until the raster is 205 mm
(± 2 mm) or 8 3/32 in. (±
1/16 in.) wide.

remove the

Adjustments Geometry - 25

Vertical Linearity

1 Use Display Service

Utility to display the
Crosshatch I test

Crosshatch I

V-LIN

Control

pattern.

2 Using a plastic

screwdriver, adjust the
V-LIN control until the
distance between the
horizontal lines is the
same at the top and
bottom of the screen.

Adjustments Geometry - 26

Vertical Hold

1 Use Display Service

Utility to display the

All-White Screen

V-HOLD

Control

All-White Screen test
pattern.

2 Using a plastic

screwdriver, adjust the
V-HOLD control
(VR401) until the
raster stabilizes.

To check the
adjustment, switch the
monitor off and on. If the
raster stabilizes
immediately, V-HOLD is
correctly set.

Adjustments Geometry - 27

Horizontal Hold

Using the plastic
screwdriver, adjust the H­HOLD control (VR502) until
the raster stabilizes.

To check the adjustment,
switch the monitor off and
on. If the raster stabilizes
immediately, H-HOLD is
correctly set.

H-HOLD

Control

Adjustments Geometry - 28

Focus

1 Use Display Service

Utility to display the
Focus test pattern.

Focus

FOCUS

Control

2 Using a plastic

screwdriver, adjust the
FOCUS control until the
Focus test pattern is as
clear as possible.

Adjustments Video - 29

Video

Before you begin,

• Remove the cover

Video

Adjustment
Controls

• Remove the EMI shield

• Remove the video board
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 - 30

Caution:

adjustments are made 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:

adjustments only if the color
quality is unacceptable.

Because

Perform video

Adjustments Video - 31

White Balance

Note:

Complete any

necessary geometry

Brightness
Contrast

Full Black Screen

adjustments before
performing the white
balance adjustments.

1 Turn on monitor power

and let the monitor
warm up for at least 10
minutes.

2 Use Display Service

Utility to display the
Full Black Screen.

3 Set the brightness

control and the contrast
control to maximum.

Adjustments Video - 32

SUB-CONTRAST

DRIVE-BLUE

Control

DRIVE-RED

Control

Control

Green, Red, and
Blue Cutoff Controls

4 Preset these adjustment

controls:

• GREEN, RED, and
BLUE CUTOFF
controls to minimum.

• DRIVE-RED and
DRIVE-BLUE controls
to midrange.

• SUB-CONTRAST
control (VR201) to
midrange.

Adjustments Video - 33

5 Adjust the SUB-BRIGHT

control (VR202) until
you cannot see the
raster, then turn up the
SUB-BRIGHT control
until the raster is
visible.

6 Adjust the GREEN CUT-

OFF control until green

SUB-BRIGHT

Control

GREEN

CUT-OFF

Control

is the predominant color.

Note:

The screen should
be dark, but with an
obvious green tint.

Adjustments Video - 34

7 Use Display Service

Utility to display the
Gray Bars test pattern.

RED CUT-OFF

Control

Brightness

BLUE CUT-OFF

Control

Gray Bars

8 Set the brightness knob

to the center (detent)
position.

9 Alternately adjust the

RED and BLUE CUT-OFF
controls until there is no
predominant color in
the left three bars.