Nokia 920C User manual

Manual
SERVICE
920C - 720C COLOR MONITOR
CONTENTS
1. Precautions
2. Product Specifications
3. Disassembly & Reassembly
4. Alignment & Adjustments
5. Troubleshooting
6. Exploded View & Parts List
7. Electrical Parts List
8. Block Diagram
9. Wiring Diagram
10. Schematic Diagrams
BH68-00294B rev. .2
Note: Sections 6, 8, 9 and 10 are in hardcopy format in the printed supplement.

WARNINGS
1. For continued safety, do not attempt to modify the
circuit board.
2. Disconnect the AC power before servicing.
3. When the chassis is operating, semiconductor
heatsinks are potential shock hazards.
1-1-1 Servicing the High Voltage VR
and CRT :
WARNING:A high voltage VR replaced in the wrong
direction may cause excessive X-ray
emissions.
Caution: When replacing the high voltage
adjustment VR, it must be fixed by a
soldering iron after it is properly set.
1. When servicing the high voltage system, remove
the static charge by connecting a 10 kohm resistor
in series with an insulated wire (such as a test
probe) between the chassis and the anode lead.
2. If the HV VR requires adjustment, (a) Replace the
VR and adjust the high voltage to the specification.
(b) Use a soldering iron to melt the adjustment cap
on the HV VR to prevent any movement.
3. When troubleshooting a monitor with excessively
HV, avoid being unnecessarily close to the monitor.
Do not operate the monitor for longer than is
necessary to locate the cause of excessive voltage.
4. High voltage should always be kept at the rated
value, no higher. Only when high voltage is
excessive are X-rays capable of penetrating the shell
of the CRT, including the lead in glass material.
Operation at high voltages may also cause failure of
the CRT or high voltage circuitry.
5. When the HV regulator is operating properly, there
is no possibility of an X-ray problem. Make sure the
HV does not exceed its specified value and that it is
regulating correctly.
6. The CRT is especially designed to prohibit
X-ray emissions. To ensure continued X-ray
protection, replace the CRT only with one that is
the same or equivalent type as the original.
7. Handle the CRT only when wearing shatterproof
goggles and after completely discharging the high
voltage anode.
8. Do not lift the CRT by the neck.
1-1-2 Fire and Shock Hazard :
Before returning the monitor to the user, perform the
following safety checks:
1. Inspect each lead dress to make certain that the
leads are not pinched or that hardware is not
lodged between the chassis and other metal parts in
the monitor.
2. Inspect all protective devices such as nonmetallic
control knobs, insulating materials, cabinet backs,
adjustment and compartment covers or shields,
isolation resistor-capacitor networks, mechanical
insulators, etc.
3. Leakage Current Hot Check (Figure 1-1):
WARNING: Do not use an isolation transformer during
this test.
Use a leakage current tester or a metering system
that complies with American National Standards
Institute (ANSI C101.1, Leakage Current for
Appliances), and Underwriters Laboratories (UL
Publication UL1410, 59.7).
4. With the unit completely reassembled, plug the AC
line cord directly into a 120V AC outlet. With the
unitÕs AC switch first in the ON position and then
OFF, measure the current between a known earth
ground (metal water pipe, conduit, etc.) and all
exposed metal parts, including: metal cabinets,
screwheads and control shafts. The current
measured should not exceed 0.5 milliamp. Reverse
the power-plug prongs in the AC outlet and repeat
the test.
Figure 1-1. Leakage Current Test Circuit
1-1-4 Product Safety Notices
Some electrical and mechanical parts have special
safety-related characteristics which are often not
evident from visual inspection. The protection they give
may not be obtained by replacing them with
components rated for higher voltage, wattage, etc. Parts
that have special safety characteristics are identified by
on schematics and parts lists. A substitute
replacement that does not have the same safety
characteristics as the recommended replacement part
might create shock, fire and / or other hazards. Product
safety is under review continuously and new
instructions are issued whenever appropriate.
Components identified by on schematics and parts
lists must be sealed by a soldering iron after
replacement and adjustment.
720C/920C 1-1
1 Precautions
1-1 Safety Precautions
!
DEVICE
UNDER
TEST
TEST ALL
EXPOSED METAL
SURFACES
(READING SHOULD
NOT BE ABOVE 0.5mA)
LEAKAGE
CURRENT
TESTER
2-WIRE CORD
ALSO TEST WITH
PLUG REVERSED
(USING AC ADAPTER
PLUG AS REQUIRED) EARTH
GROUND

1. Servicing precautions are printed on the cabinet,
and should be followed closely.
2. Always unplug the unitÕs AC power cord from the
AC power source before attempting to: (a) remove
or reinstall any component or assembly, (b)
disconnect PCB plugs or connectors, (c) connect all
test components in parallel with an electrolytic
capacitor.
3. Some components are raised above the printed
circuit board for safety. An insulation tube or tape
is sometimes used. The internal wiring is
sometimes clamped to prevent contact with
thermally hot components. Reinstall all such
elements to their original position.
4. After servicing, always check that the screws,
components and wiring have been correctly
reinstalled. Make sure that the area around the
serviced part has not been damaged.
1. Immediately before handling any semiconductor
components or assemblies, drain the electrostatic
charge from your body by touching a known earth
ground. Alternatively, wear a discharging wrist-
strap device. To avoid a shock hazard, be sure to
remove the wrist strap before applying power to
the monitor.
2. After removing an ESD-equipped assembly, place it
on a conductive surface such as aluminum foil to
prevent accumulation of an electrostatic charge.
3. Do not use freon-propelled chemicals. These can
generate electrical charges sufficient to damage
ESDs.
4. Use only a grounded-tip soldering iron to solder or
desolder ESDs.
5. Use only an anti-static solder removal device. Some
solder removal devices not classified as Òanti-staticÓ
can generate electrical charges sufficient to damage
ESDs.
5. Check the insulation between the blades of the AC
plug and accessible conductive parts (examples:
metal panels, input terminals and earphone jacks).
6. Insulation Checking Procedure: Disconnect the
power cord from the AC source and turn the power
switch ON. Connect an insulation resistance meter
(500 V) to the blades of the AC plug.
The insulation resistance between each blade of the
AC plug and accessible conductive parts (see
above) should be greater than 1 megohm.
7. Never defeat any of the +B voltage interlocks. Do
not apply AC power to the unit (or any of its
assemblies) unless all solid-state heat sinks are
correctly installed.
8. Always connect a test instrumentÕs ground lead to
the instrument chassis ground before connecting the
positive lead; always remove the instrumentÕs
ground lead last.
6. Do not remove a replacement ESD from its
protective package until you are ready to install it.
Most replacement ESDs are packaged with leads
that are electrically shorted together by conductive
foam, aluminum foil or other conductive materials.
7. Immediately before removing the protective
material from the leads of a replacement ESD,
touch the protective material to the chassis or
circuit assembly into which the device will be
installed.
Caution: Be sure no power is applied to the
chassis or circuit and observe all
other safety precautions.
8. Minimize body motions when handling
unpackaged replacement ESDs. Motions such as
brushing clothes together, or lifting your foot from
a carpeted floor can generate enough static
electricity to damage an ESD.
9. Indicates ESDs on the Schematic Diagram in
this manual.
1 Precautions
1-2 720C/920C
1-3 Electrostatically Sensitive Devices (ESD) Precautions
Some semiconductor (solid state) devices can be easily damaged by static electricity. Such components are commonly
called Electrostatically Sensitive Devices (ESD). Examples of typical ESD devices are integrated circuits and some field-
effect transistors. The following techniques will reduce the incidence of component damage caused by static electricity.
1-2 Servicing Precautions
WARNING1: First read the “Safety Precautions” section of this manual. If unforeseen circumstances
create conflict between the servicing precautions and safety precautions, always
follow the safety precautions.
WARNING2: A high voltage VR replaced in the wrong direction may cause excessive X-ray
emissions.
WARNING3: An electrolytic capacitor installed with the wrong polarity might explode.

2 Product Specifications
2-1 Specifications
Picture Tube: 17-Inch (43 cm): 16-inch (40.6 cm) viewable, 19-Inch (48.2 cm): 18-inch (45.8 cm) viewable,
17”/19”: 0.26 mm Dot pitch
Full-square flat-face tube, 90˚ Deflection (720C), 100˚ Deflection (920C),
Anti-Reflection coating with Anti-electrastatic, Medium short persistence phosphor
Scanning Frequency Horizontal : 720C/920C: 30 kHz to 96 kHz (Automatic),
(Automatic)
Vertical : 50 Hz to 160 Hz (Automatic)
Display Colors Unlimited colors
Maximum Resolution Horizontal :17”/19”/: 1600 Dots
Vertical :17”/19”/: 1200 Lines
Input Video Signal Analog, 0.7 Vp-p positive at 75 Ω, internally terminated
Input Sync Signal Separate Sync : TTL level positive/negative
Composite Sync : TTL level positive/negative
Sync-on-Green : Composite sync 0.3 Vp-p negative (Video on Vp-p positive)
Maximum Pixel Clock rate 17”/19" : 205 MHz
Active Display 17” ; Horizontal : 310 mm ± 3 mm (12.2”±0.12”)
Vertical : 232mm ± 3 mm (9.13”±0.12”)
19” ; Horizontal : 355mm ± 3 mm (13.98” ± 0.12”)
Vertical : 266mm ± 3mm(10.47”±0.12”)
Input Voltage AC 90 to 264 Volts, 60/ 50 Hz ± 3 Hz
Power Consumption (max) 17”: 120 Watt , 19”: 135Watt
Dimensions Unit ; 17” : 16.3 x 16.9 x 17.2 Inches (415.0 x 430.3 x 438 mm)
(W x D x H) 19” : 18.4 x 19.6 x 19.0 Inches (468.0 x 499.0 x 483.2 mm)
Carton ; 17” : 21.1 x 22.3 x 21.9 Inches (535 x 566 x 555 mm)
19” : 22.6 x 23.2 x 22.8 Inches (573.0 x 590.0 x 580.0 mm)
Weight (Net/Gross) 17” : 39.0 lbs (17.7 kg) / 45.6 lbs (20.7 kg)
(Net/Gross) 19” : 49.6 lbs (22.5 kg) / 58.8 lbs (26.7 kg)
Environmental Considerations Operating Temperature : 32°F to 104°F (0°C to 40°C)
Humidity : 10 % to 80 %
Storage Temperature : -4°F to 113°F (-20°C to 45°C)
Humidity : 5 % to 95 %
•920C/720C complies with TCO 99 recommendations for reduced electromagnetic fields.
• Designs and specifications are subject to change without prior notice.
720C/920C 2-1
Item Description

2 Product Specifications
2-2 720C/920C
QRS
P
O
Video
Sync Sync
Horizontal Vertical
CDE
P
O
B
A
Video
Sync Sync
Separate Sync
A : Line time total B : Horizontal sync width O : Frame time total P : Vertical sync width
C : Back porch D : Active time Q : Back porch R : Active time
E : Front porch S : Front porch
B
Green Vertical
PQRS
O
Horizontal
Sync-on-Green
800/85 Hz
800 x 600 1600/75 Hz 1600 x 1200
1024/75 Hz
1024 x 768
640/85Hz
640 x 480
VGA2/70Hz
720 x 400
Table 2-1. Timing Chart
fH (kHz)
A µsec
B µsec
C µsec
D µsec
E µsec
fV (Hz)
O msec
P msec
Q msec
R msec
S msec
Clock
Freq.
(MHz)
Polarity
H.Sync
V.Sync
Remark
31.469
31.778
3.813
1.907
25.422
0.636
70.087
14.268
0.064
1.080
12.711
0.413
28.322
Negative
Positive
Separate
43.269
23.111
1.556
2.222
17.778
1.556
85.008
11.764
0.069
0.578
11.093
0.023
36.000
Negative
Negative
Separate
60.023
16.660
1.219
2.235
13.003
0.203
75.025
13.328
0.050
0.466
12.795
0.017
78.75
53.674
18.631
1.138
2.702
14.222
0.569
85.061
11.756
0.056
0.503
11.179
0.019
56.250
Positive
Positive
Separate
93.750
10.667
0.948
1.501
7.901
0.316
75.000
13.333
0.032
0.491
12.800
0.011
202.500
Positive
Positive
Separate
Mode IBM VESA MAC.
Timing
68.677
14.561
1.016
2.201
10.836
0.508
84.997
11.765
0.044
0.524
11.183
0.015
94.500
Positive
Positive
Separate
49.726
20.110
4.117
3.910
14.524
0.559
75.000
13.414
0.060
0.784
12.549
0.020
57.284
SOG
68.681
14.560
1.280
1.440
11.520
0.320
75.062
13.322
0.044
0.568
12.667
0.044
100.000
Negative
Negative
SOG
91.146
10.971
1.016
1.422
8.127
0.406
85.024
11.761
0.033
0.483
11.235
0.011
157.500
Positive
Positive
Separate
79.976
12.504
1.067
1.837
9.481
0.119
75.025
13.329
0.038
0.475
12.804
0.013
135.000
Positive
Positive
Separate
1024/85 Hz
1024 x 768 832/75 Hz 832 x 624 1152/75 Hz 1152 x 870
1280/75 Hz
1280 x 1024 1280/85 Hz 1280 x 1024
Negative
Negative
Positive
Positive
Separate

3-1-1 Before making Disassembly
1.Disconnect power cord from the monitor.
2. With a pad beneath it, stand the monitor on its
front with the screen facing downward and
the base close to you.
3. Make sure nothing will damage the screen.
3-1-2 Cabinet Disassembly
1.Remove the 4 screws on the Rear Cover and
pull it upward to remove it.
3-1-3 Removing the Stand
Pull the tab outward on the Chassis Bottom
and pull the Tilt and Swivel Base up to
remove it.
3-1-4 Removing the Top Shield
Remove the 4screws on the Top Shield Cover
and remove the Shield.
3-1-5 Removing the Bottom Shield
1. Remove the 1 screw on the Bottom Shield
Cover.
2. Lift off the Bottom Shield.
3-1-6 Removing the Video PCB Assembly
1. Remove the Video PCB from the CRT.
2.Disconnect CN102, CN101, CN12 and CN13
on the Video PCB Assembly and Video PCB
AssÕy from the CRT Neck.
720C/920C 3-1
3 Disassembly and Reassembly
This section of the service manual describes the disassembly and reassembly procedures for the
Nokia 920C/720C (19" ~ 17") monitors.
WARNING: This monitor contains electrostatically sensitive devices. Use caution when handling
these components.
3-1 Disassembly
Cautions:1. Disconnect the monitor from the power source before disassembly.
2. Follow these directions carefully; never use metal instruments to pry apart the cabinet.

3-1-7 Removing the Video PCB Assembly
Rear Shield and Video PCB
1. Remove the 3 screws on the PCB Assembly.
2. Remove the Video PCB Assembly Rear Shield.
(5 point)
3. Lift out the Video PCB and pleat it on a flat,
level surface that is protected from static
electricity.
3-1-8 Removing the Main PCB Assembly
1. Remove both side screws (4 screws) on the
lower edge of the CRT Bracket.
2. Remove Chassis Ground Wire on the both
side.
3. Disconnect CN201, CN409, CN601, H_DY,
CN604 and Anode Cap on the Main PCB
Assembly.
3-1-9 Removing the Main PCB
1. Remove 6 screws on the main PCB.
2. Pull the Main PCB towards you and carefully
lift out the main PCB and placet it on a flat,
level surface that is protected from static
electricity.
3-1-10 Removing the Bracket
1. Remove the 10 screws on the Front Cabinet.
3-1-11 Removing the Degaussing Coil
1. Using pinch-nosed pliers or long-nosed pliers,
carefully push the 4 plastic ties on the Bracket.
2. Lift the Degaussing Coil Assembly from the
Bracket.
3 Disassembly and Reassembly
3-2 720C/920C
3-2 Reassembly
Reassembly procedures are in the reverse order of Disassembly procedures.

4-1-1 Before Making Adjustments
4-1-1 (a) ORIENTATION
When servicing, always face the monitor to the
east.
4-1-1 (b) MAGNETIC FIELDS
Whenever possible, use magnetic field isolation
equipment such as a Helmholtz field to surround
the monitor. If a Helmholtz field is not available,
frequently degauss the unit under test.
Caution: Other electrical equipment may cause
external magnetic fields which may
interfere with monitor performance.
Use an external degaussing coil to limit magnetic
build up on the monitor. If an external degaussing
coil is not available, use the internal degaussing
circuit. However, do not use the internal
degaussing circuit more than once per 30 minutes.
4-1-1 (c) WARM-UP TIME
The monitor must be on for 30 minutes before
starting alignment. Warm-up time is especially
critical in color temperature and white balance
adjustments.
4-1-1 (d) SIGNAL
Analog, 0.7 Vp-p positive at 75 ohm, internal
termination
Sync: Separate/Composite
(TTL level negative/positive)
Sync-on-Green:
Composite sync 0.3 Vp-p negative
(Video 0.7 Vp-p positive)
4-1-1 (e) SCANNING FREQUENCY
Horizontal: 30 kHz to 96 kHz (Automatic)
Vertical: 50 Hz to 160 Hz (Automatic)
Unless otherwise specified, adjust at the
1024 x 768 mode (H: 68 kHz, V: 85 Hz) signals.
Refer to Table 2-1 on pages 2-2 and 2-3.
4-1-1 (f) HIGH VOLTAGE ADJUSTMENT
Signal: 1024 x 768 mode (68 kHz/85 Hz)
Display image: Full white
Contrast: Maximum
Brightness: Maximum
Limit: 27.3 kV ± 0.5 kV
(17Ó: 26 kV ± 0.5 kV)
Measure the hight voltage level at the anode cap.
High voltage should be within the limit as above.
If the high voltage needs adjustment, use the VR501.
4-1-1 (g) G2 (SCREEN) VOLTAGE ADJUSTMENT
Signal: 1024 x 768 mode (68 kHz/85 Hz)
Display image: Full white
Contrast: Maximum
Brightness: Maximum
Adjust the Screen VR of the FBT so that the G2
(Screen) Voltage for Toshiba it is 540 V ± 10 V.
4-1-1 (h) CENTER RASTER
Adjust VR401 so that the back raster comes to the
center when you apply a signal of 91 kHz/85 Hz.
720C/920C 4-1
4 Alignment and Adjustments
This section of the service manual explains how to make permanent adjustments to the monitor. Direction
is given for adjustment using the monitor Interface Board Ver. 2.0 and software (Softjig).
4-1 Adjustment Conditions
Caution: Changes made without the Softjig are saved only to the user mode settings. As such, the
settings are not permanently stored and may be inadvertently deleted by the user.
720C SDD TOSHIBA
G2 525V 635V
920C
G2 560V 530V
MEC SDD

4-1-1 (i) BRIGHTNESS AND CONTRAST
Unless otherwise specified, adjust control
volumes:
Brightness: Maximum
Contrast: Maximum
4-1-2 Required Equipment
The following equipment may be necessary for
adjustment procedures:
4-1-2 (a) DISPLAY CONTROL ADJUSTMENT
1. Non-metallic (Ð) screwdriver: 1.5 mm
Non-metallic (Ð) screwdriver: 3 mm
2. Philips (+) screwdriver: 1.5 mm
3. Non-metallic hexkey: 2.5 mm
4. Digital Multimeter (DMM), or
Digital Voltmeter (DVM)
5. Signal generator, or
Computer with a video board that uses the
ET-4000 chipset (strongly recommended if
using Samsung DM 200 software) and that
displays: 1280 x 1024 @ 85 Hz, or 1600 x 1200
@ 85 Hz (maximum).
6. Personal computer
7. Required software: Softjig.exe from Samsung
which includes the Nokia19SDD.MDL
(SDD CRT) data file
Samsung DM200, or DisplayMate for
Windows from Sonera Technologies
8. Interface Board Ver. 2.0 Code No.
BH81-90001K
9. Parallel communications cable (25-pin to
25-pin); Code No. BH81-90001H
10. Signal cable (15-pin to 15-pin cable with
additional 3-pin connector); Code No.
BH81-90001J
11. 5 V DC adapter, not supplied
Note: Softjig AssÕy (includes items 8, 9 and 10)
Code No. BH81-90001L
4-1-2 (b) COLOR ADJUSTMENTS
1. All equipment listed in 4-1-2 (a), above
2. Color analyzer, or any luminance
measurement equipment
4-1-3 Connecting the SoftJig
Connect the monitor to the signal generator and/
or PC as illustrated in Figures 4-1 and 4-2.
Note: The signal cable connector which includes
the 3-wire cable must connect to the
monitor. If you use Setup 2 (PC only, no
signal generator) you can only make
adjustments to the signal timing available
on that computer system. To make
corrections to all factory timings requires
the use of an additional signal generator.
4-1-4 After Making Adjustments
After finishing all adjustments, test the monitor in
all directions. If, for example, the monitor does not
meet adjustment specifications when facing north,
reposition the monitor to face east and readjust.
This time, try for an adjustment closer to the ideal
setting within the tolerance range. Test the unit
again in all directions. If the monitor again fails to
meet specifications in every direction, contact
your Regional After Service Center for possible
CRT replacement.
4 Alignment and Adjustments
4-2 720C/920C
MONITOR
INTERFACE
BOARD VER. 2.0
PC SIGNAL
GENERATOR
3-WIRE
CABLE
SIGNAL CABLE
5V DC
ADAPTOR
PARALLEL CABLE
Figure 4-1. Setup 1, With Signal Generator
MONITOR
INTERFACE
BOARD VER. 2.0
PC
3-WIRE CABLE
SIGNAL CABLE
PARALLEL CABLE D-SUB
CONNECTOR
5V DC
ADAPTOR
Figure 4-2. Setup 2, Without Signal Generator

4-2-1 Centering
Centering means to position the center point of
the display in the middle of the display area.
Horizontal size and position and vertical size and
position control the centering of the display.
Adjust the horizontal size and vertical size to their
optimal settings: 355 mm (H) x 266 mm (V)/920C.
310 mm x 232 mm/720C. 1280 x 1024 mode (91kHz/85Hz)
Adjust the horizontal position and vertical
position to ²4.0 mm of the center point of the
screen.
|A-B| ² 4.0 mm. |C-D| ² 4.0 mm.
Figure 4-3. Centering
4-2-1 (a) HORIZONTAL SIZE ADJUSTMENT
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to H_SIZE to
adjust the horizontal size of the display pattern to
355 mm. (Tolerance: ±3 mm.)
4-2-1 (b) VERTICAL SIZE ADJUSTMENT
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to V_SIZE to
adjust the vertical size of the display pattern to
266 mm. (Tolerance: ±3 mm.)
4-2-1 (c) HORIZONTAL POSITION ADJUSTMENT
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to H_POSI to
center the horizontal image on the raster.
4-2-1 (d) VERTICAL POSITION ADJUSTMENT
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to V_POSI to
center the vertical image on the raster.
4-2-2 Linearity
Linearity affects the symmetry of images as they
appear on the screen. Unless each row or column
of blocks in a crosshatch pattern is of equal size,
or within the tolerances shown in Tables 4-1 and
4-2, an image appears distorted, elongated or
squashed.
Table 4-1. Factory Preset Modes Linearity
Table 4-2. Other Modes Linearity: VGA, SVGA, XGA,
MAC, etc.
4-2-2 (a) HORIZONTAL LINEARITY ADJUSTMENT
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
To adjust the Horizontal Linearity, refer to Tables
4-1 and 4-2 for the tolerance range.
Click on the << or >> box next to H_LIN to
optimize the image.
4 Alignment and Adjustments
720C/920C 4-3
4-2 Display Control Adjustments
C
A
DISPLAY AREA
EDGE OF BEZEL
B
D
4 : 3 Horizontal: 20.5~23.5
Vertical : 20.5~23.5
Supported Timing Mode
Each block (14 %) Difference between
adjacent blocks (5 %)
Horizontal: Less than 1.10 mm
Vertical : Less than 1.10 mm
4 : 3 Horizontal: 20.9~23.1
Vertical : 20.9~23.1
Standard Modes Linearity
Each block (10 %) Difference between
adjacent blocks (4 %)
Horizontal: Less than 0.88 mm
Vertical : Less than 0.88 mm

4-2-2 (b) VERTICAL LINEARITY ADJUSTMENT
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
To adjust the Vertical Linearity, refer to Tables 4-1
and 4-2 for the tolerance range.
Click on the << or >> box next to V_LIN to
optimize the image.
4-2-3 Trapezoid Adjustment
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to TRAP to make
the image area rectangular.
Figure 4-4. Trapezoid
4-2-4 Pinbalance Adjustment
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to PIN_BAL to
optimize the image.
4-2-5 Parallelogram Adjustment
CONDITIONS
Scanning Frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to PARALLEL to
make the image area rectangular.
Figure 4-6. Parallelogram
4-2-6 Side Pincushion Adjustment
CONDITIONS
Scanning frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to BARREL to
straighten the sides of the image area.
4-2-7 Tilt Adjustment
CONDITIONS
Scanning Frequency: 91 kHz/85 Hz
Display image: Crosshatch pattern
Brightness: Cut-off
Contrast: Maximum
Click on the << or >> box next to ROTATE to
correct the tilt of the display.
4-2-8 Degauss
No adjustments are available for the degaussing
circuit. The degaussing circuit can effectively
function only once per 30 minutes.
4-2-9 To Delete the User Mode Data
To delete the adjustment data from the user
modes, press the EXIT Button for 15 seconds.
4-2-10 Save the Data
To save the adjustment data for a mode, press
FACTORY SAVE.
4 Alignment and Adjustments
4-4 720C/920C
| C1 |, | C2 | ≤2.0 mm, | D1 |, | D2 | ≤2.0 mm.
Figure 4-7. Pincushion
A
5 mm
B
A
B
| D1 |, | D2 | ≤2.0 mm
Figure 4-5. Pinbalance
D1 D2 D1
C2
D2D1
C1
| A - B | < 5 mm

4-3-1 Color Coordinates (Temperature)
Color temperature is a measurement of the
radiant energy transmitted by a color. For
computer monitors, the color temperature refers
to the radiant energy transmitted by white. Color
coordinates are the X and Y coordinates on the
chromaticity diagram of wavelengths for the
visible spectrum.
CONDITIONS
Measurement instrument: Color analyzer
Scanning frequency: 68 kHz/85 Hz
Display Size : 355 (H) x 266 (V)/920C ~ 310 X 232/720C
Display image: White flat field at
center of display area
Brightness:Cut-off
Contrast: Maximum
PROCEDURE
Use the directions in sections 4-3-2 through 4-3-4
to adjust the color coordinates for:
9300K to x = 0.283 ±0.02, y = 0.297±0.02
6500K to x = 0.313 ± 0.02, y = 0.329 ± 0.02
5000K to x = 0.346 ± 0.02, y = 0.359 ± 0.02
4-3-2 Color Adjustments for 9300K
4-3-2 (a) BACK RASTER COLOR ADJUSTMENT
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: Back raster pattern
Brightness: Cut-off
Contrast: Maximum
1. Select COLOR CHANNEL 1 to control the
color for 9300K.
2. Adjust the luminance of the back raster to
between 0.3 to 1ft-L using the G_CUT
controls.
3. Click on the << or >> box next to B_CUT to
set the ÒyÓ coordinate to 0.297 ±0.02.
4. Click on the << or >> box next to R_CUT to
set the ÒxÓ coordinate to 0.283 ± 0.02.
Note: If the above adjustments cannot be
done to each coordinate, click on the
<< or >> box next to G_CUT to decrease
or increase the green cutoff (bias) and
repeat procedures 2 and 3.
4-3-2 (b) G-GAIN ADJUSTMENT
Figure 4-8. Green Box Pattern
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: Green box pattern
Brightness: Cut-off
Contrast: Maximum
1. Click on the << or >> box next to G_GAIN to
adjust the brightness of the Green Gain to
25 ± 1 ft-L.
Note: If you canÕt increase the Green Gain to
the appropriate value, click on the >>
box next to increase the ABL point.
4-3-2 (c) WHITE BALANCE ADJUSTMENT
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: Full white pattern
Brightness: Cut-off
Contrast: Maximum
Figure 4-9. Full White Pattern
1. Click on the << or >> boxes next to R_GAIN
and B_GAIN to make the video white.
(For 9300K color adjustment:
x = 0.283 ±0.02, y = 0.297 ±0.02.)
Note: Do not touch the G_GAIN controls.
2. Check the ABL. If it is not within the
specifications (30 ± 1 ft-L), use the ABL
controls to adjust it.
3. Select COLOR FACTORY SAVE to save the
data.
4 Alignment and Adjustments
720C/920C 4-5
4-3 Color Adjustments
1/3H-1/2H
1/3V-1/2V
FRONT BEZEL OPENING
BACK RASTER
GREEN WINDOW
FRONT BEZEL OPENING
BACK RASTER
WHITE WINDOW

4-3-2 (d) WHITE BALANCE ADJUSTMENT VERIFICATION
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: Back raster pattern
X-Y Coordinates: x = 0.283 ± 0.02,
y = 0.297 ±0.02
Raster Luminance 0.3 ~ 1ft-L
ABL Luminance 30 ± 1 ft-L
Brightness: Cut-off
Contrast: Maximum
1. Check whether the color coordinates of the
back raster satisfy the above spec.
If they do not, return to 4-3-2 (a) and readjust
all settings.
2. Display a full white pattern.
Note: Do not touch the G_GAIN controls.
3. Adjust the Contrast Control on the monitor so
that the luminance of the video is about 5 ft-L.
4. Check whether the white coordinates of the
video meet the above coordinates spec.
5. Adjust the Contrast Control again so that the
luminance of the video is about 20 ft-L.
6. Check whether the white coordinates of the
video satisfies the above spec.
If they do not, return to 4-3-2 (a) and readjust
all settings.
4-3-3 Color Adjustments for 6500K
4-3-3 (a) BACK RASTER COLOR ADJUSTMENT
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: Back raster pattern
Brightness: Cut-off
Contrast: Maximum
1. Select COLOR CHANNEL 2 to control the
color for 6500K.
2. Adjust the luminance of the back raster to
between 0.3 to 1.0 ft-L using the G_CUT
controls.
3. Click on the << or >> boxes next to R_CUT
and B_CUT to adjust the R-Bias to x = 0.313 ±
0.02 and the B-Bias to y = 0.329 ± 0.02.
4-3-3 (b) G-GAIN ADJUSTMENT
This procedure is the same as that for 9300K, refer
to the procedure on page 4-5.
4-3-3 (c) WHITE BALANCE ADJUSTMENT
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: Full white pattern
Brightness: Cut-off
Contrast: Maximum
1. Click on the << or >> boxes next to R_GAIN
and B_GAIN to make the video white.
(For 6500K color adjustment:
x = 0.313 ± 0.02, y = 0.329 ± 0.02.)
2. Refer to the procedure for 9300K, section
4-3-2 (c) steps 2 and 3.
4-3-3 (d) WHITE BALANCE ADJUSTMENT VERIFICATION
Refer to the procedure for 9300K, section 4-3-2 (d).
4-3-4 Color Adjustments for 5000K
4-3-4 (a) BACK RASTER COLOR ADJUSTMENT
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: Back raster pattern
Brightness: Cut-off
Contrast: Maximum
1. Select COLOR CHANNEL 3 to control the
color for 5000K.
2. Adjust the luminance of the back raster to
between 0.3 to 1.0 ft-L using the G_CUT
controls.
3. Click on the << or >> boxes next to R_CUT
and B_CUT to adjust the R-Bias to x = 0.346 ±
0.02 and the B-Bias to y = 0.359 ± 0.02.
4-3-4 (b) G-GAIN ADJUSTMENT
This procedure is the same as that for 9300K, refer
to the procedure on page 4-5.
Adjust the brightness of the G_GAIN less 5 ft-L
than brightness of procedure for 9300K.
4-3-4 (c) WHITE BALANCE ADJUSTMENT
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: Full white pattern
Brightness: Cut-off
Contrast: Maximum
1. Click on the << or >> boxes next to R_GAIN
and B_GAIN to make the video white.
(For 5000K color adjustment:
x = 0.346 ± 0.02, y = 0.359 ± 0.02.)
2. Refer to the procedure for 9300K, section
4-3-2 (c) steps 2 and 3.
4 Alignment and Adjustments
4-6 720C/920C

4-3-4 (d) WHITE BALANCE ADJUSTMENT VERIFICATION
Refer to the procedure for 9300K, section 4-3-2 (d).
4-3-5 Luminance Uniformity Check
Luminance is considered uniform only if the ratio
of lowest to highest brightness areas on the screen
is not less than 7.5:10.
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
(1024 x 768)
Display image: White flat field
Display size: 355(H) x 266(V)/920C ~ 310(H) X 232(V)/720C
Brightness: Cut off point
Contrast: Maximum
PROCEDURE
Measure luminance at nine points on the display
screen (see figure below).
4-3-6 Focus Adjustment
CONDITIONS
Scanning frequency: 68 kHz/85 Hz
Display image: ÒHÓ character pattern
Brightness: Cut off point
Contrast: Maximum
PROCEDURE
1. Adjust the Focus VR on the FBT to display the
sharpest image possible.
2. Use Locktite to seal the Focus VR in position.
4-3-7 Color Purity Adjustment
Color purity is the absence of undesired color.
Conspicuous mislanding (unexpected color in a
uniform field) within the display area shall not be
visible at a distance of 50 cm from the CRT
surface.
CONDITIONS
Orientation: Monitor facing east
Scanning frequency: 68 kHz/85 Hz
Display image: White flat field
Luminance: Cut off point at the center
of the display area
Note: Color purity adjustments should only be
attempted by qualified personnel.
PROCEDURE (adjusting convergence)
For trained and experienced service technicians
only.
Use the following procedure to correct minor
color purity problems:
1. Make sure the display is not affected by
external magnetic fields.
2. Very carefully break the glue seal between the
2-pole purity convergence magnets (PCM), the
band and the spacer.
3. Make sure the spacing between the PCM
assembly and the CRT stem is 29 mm ± 1 mm.
4. Display a green pattern over the entire display
area.
5. Adjust the purity magnet rings on the PCM
assembly to display a pure green pattern.
(Optimum setting: x = 0.295 ± 0.015,
y = 0.594 ± 0.015)
6. Repeat steps 4 and 5 using a red pattern and
then again, using a blue pattern.
Table 4-3. Color Purity Tolerances
(For 9300K color adjustment: x = 0.283 ± 0.02, y = 0.297 ± 0.02)
7.When you have the PCMs properly adjusted,
carefully glue them together to prevent their
movement during shipping.
4 Alignment and Adjustments
720C/920C 4-7
Red: x = 0.620 ± 0.015 y = 0.334 ± 0.015
Green: x = 0.289 ± 0.015 y = 0.595 ± 0.015
Blue: x = 0.153 ± 0.015 y = 0.072 ± 0.015
Figure 4-10 Luminance Uniformity Check Locations

720C/920C 5-1
5 Troubleshooting
5-1 Parts Level Troubleshooting
Notes: 1. If a picture does not appear, fully rotate the brightness and contrast controls clockwise and reinspect.
2. Check the following circuits.
• No raster appears: Power circuit, Horizontal output circuit, H/V control circuit, and H/V output circuit.
• High voltage develops but no raster appears: Video output circuits.
• High voltage does not develop: Horizontal output circuits.
5-1-1 No Power Supply
Check and replace FG601, D601,
IC661, IC662.
Done.
Repeating start? Check and replace D601, D604, D663,
Q632, and Q664.
No
Yes
IC601 Pin 1 waveform is right? Check and replace IC601,
IC602, IC604.
Yes
No
IC602 and IC604
are right? Replace parts and verify voltages.
Yes
No
Normal operation Replace Main board.
Yes
Yes
No
WAVEFORMS
1
1544 V (IC601, #1)
CH1 P-P = 544 V CH1 RMS = 332.4 V
Verify voltages.

5 Troubleshooting
5-2 720C/920C
5-1-2 DPMS Failure
Check signal source
H/V sync video level.
Make no H/V sync (power off mode)
LED blinks Check IC201 Pin 39.
Yes
No
+12 V line off Check IC201 Pin 9.
Yes
No
Q632 Base driving voltage exists? Check IC201 Pin 10.
Check and replace Q632.
Yes
No
Done

5 Troubleshooting
720C/920C 5-3
5-1-3 H_Deflection Failure
IC402 Pin 6 waveform is right?
Q403 source waveform
is right?
Check D407, D408, Q403, R436
and R438, +210 V line.
Yes
Yes
No
1. Check R401, +12 V line.
2. Check IC402 Pins 6~5, 7~6.
3. Replace IC402.
No
Q404 gate, drain
waveforms are right?
Check Q404, R415.
Check +25 V line.
Yes
No
Q405 base, collector
waveforms are right?
Check and replace D410 and Q405.
Check DY connector connection.
Yes
No
IC261 Pin 4 is high? Replace IC261.
Check some parts around
Q261 and Q262.
Yes
No
IC261 Pin 26 waveform
is right? Check some parts around IC261.
Yes
No
WAVEFORMS
2
3
4
5
6
8
7
3230 V (Q405, Source)
CH1 P-P = 230 V CH1 RMS = 150.1 V
812.08 V (IC261, #26)
CH1 P-P = 12.08 V CH1 RMS = 7.396 V
210.96 V (IC402, #6)
CH1 P-P = 10.96 V CH1 RMS = 6.180 V
554 V (Q404, Drain)
CH1 P-P = 54 V CH1 RMS = 22.44 V
411.6 V (Q404, Gate)
CH1 P-P = 11.6 V CH1 RMS = 6.944 V
618.6 V (Q405, Base)
CH1 P-P = 55.2 V CH1 RMS = 9.52 V
71.216 kV (Q405, Collector)
CH1 P-P = 1.216 kV CH1 RMS = 316 V
Check some parts around Q263.

5 Troubleshooting
5-4 720C/920C
5-1-4 S Correction Failure
S1~S5 signals are right at each
frequency block?
Check S1 ~ S5 signal.
Check and replace
C430, C431, C433, C434, C435,
C437 C441, C453, C454, C455, C456, C457,
Q409~Q413, Q451~Q455, Q456~Q460 .
Yes
5-1-5 H_Lin. Failure
IC201 Pin 21 voltage varies with
different H_Lin. DAC values?
IC403 Pin 7, 8 voltage varies with
different H_Lin. DAC values?
Check +12 V line.
Check some parts around IC403.
Check L403.
Yes
Yes
No
Check and replace IC201.
No
Replace IC201.
No
5-1-6 Invariable H_Size
IC261 Pin 28 voltage varies with
different H_Size DAC values?
IC401 Pin 6 output duty varies with
different H_Size DAC values?
Check some parts around IC261 Pin
28, IC401.
Yes
No
Check and replace IC261.
No

5 Troubleshooting
720C/920C 5-5
5-1-7 Abnormal H_Size
T402 Pin 8 waveform is right? Check and replace T402.
Check some parts around D415, IC261
Pin 28, IC402 Pin 2 and IC201 Pin20.
Yes
No
5-1-8 Side Pin or Trap Failure
IC261 Pin 24 output exists?
Yes
Check and replace IC261.
Check and replace IC402.
Check some parts IC402 Pin 2
and IC261 Pin 24.
5-1-9 Para. or Pin Balance Failure
IC261 Pin 24 output varies with
different DAC values?
No
Replace IC261.
No
WAVEFORMS
9929.8 V (T402, #8)
CH1 P-P = 29.8 V CH1 RMS = 7.14 V

5 Troubleshooting
5-6 720C/920C
5-1-10 Tilt Failure
IC201 Pin 23 output duty varies
with different DAC values?
IC403 Pin 10, 11 output varies with
different DAC values? Check and replace IC403.
Check and replace CRT.
Yes
Yes
No
Check and replace IC201.
No
Check tilt connector connection
5-1-11 V Deflection Failure
±14 V line is on?
IC261 Pin 23 output exists? Check and replace IC261.
Yes
Yes
No
Refer to 5-1-1 No Power Supply
No
IC301 Pin 1 input exists? Check R276 and R304.
Yes
No
IC301 Pin 6 output exists? Check and replace some parts
around IC301.
Yes
No
Check V DY connector connection.