Viewsonic G90FB-4 Service Manual
Service Manual
ViewSonic G90fB-4
Model No. VS10794
19” Digital Controlled Color Monitor
(G90fB-4_SM Rev. 1a Jan. 2006)
ViewSonic® 381 Brea Canyon Road, Walnut, California 91789 USA - (800) 888-8583
TABLE OF CONTENTS
1. Precautions and Safety Notices 1
2. Specification 3
3. Front Panel Function Control Description 6
4. Circuit Description 10
5. Adjusting Procedure 13
6. Trouble Shooting Flow Chart 17
7. Recommended Spare Parts List 22
8. Exploded Diagram And Spare Parts List 37
9. Block Diagram 39
10. Schematic Diagrams 46
11. PCB Layout Diagrams 50
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Copyright
Copyright © 2005 by ViewSonic Corporation. All rights reserved. No part of this publication may be
reproduced, transmitted, transcribed, stored in a retrieval system, or translated into any language or
computer language, in any form or by any means, electronic, mechanical, magnetic, optical, chemical,
manual or otherwise, without the prior written permission of ViewSonic Corporation.
Disclaimer
ViewSonic makes no representations or war r ant ies, either expressed or implied, with r espect to the contents
hereof and specifically disclaims any warranty of merchantability or fitness for any particular purpose. Further,
ViewSonic reserves the right to revise this publication and to make changes from time to time in the contents
hereof without obligation of ViewSonic to notify any person of such revision or changes.
Trademarks
Optiquest is a registered trademark of ViewSonic Corporation.
ViewSonic is a registered trademark of ViewSonic Corporation.
All other trademarks used within this document are the property of their respective owners.
Revision History
Revision SM Editing Date ECR Number Description of Changes Editor
1a 1/9/06 Initial Release Sophia Kao
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1. Precautions and Safety Notices
WARNING!
This service information is designed for experience repair technicians only and is not designed for use by the general public.
It does not contain warnings or cautions to advise non-technical individuals of potential dangers in attempting to service
a product.
Products powered by electricity should be serviced or repaired only by experienced professional technicians.
Any attempt to service or repair the product or products dealt within this service information by anyone else
could result in serious injury or death.
1. CAUTION
No modification of any circuit should be attempted. Service work should only be performed after you are thoroughly
familiar with all of the following safety checks and servicing guide lines.
2. SAFETY CHECK
Care should be taken while servicing this CRT display because of the high voltage used in the deflection circuits.
These voltages are exposed in such areas as the associated flyback and yoke circuits.
3. FIRE & SHOCK HAZARD
3-1 Insert an isolation transformer between the CRT display and AC power line before servicing the chassis.
3-2 In servicing pay attention to original lead dress especially in the high voltage circuit. If a short circuit is found,
replace all parts which have been overheated as a result of the short circuit.
3-3 All the protective devices munt be reinstalled per original design.
3-4 Soldering must be inspected for possible cold solder joints, frayed leads, damaged insulation, solder splashes or
sharp solder points. Be certain to remove all foreign material.
4. LEAKAGE CURRENT COLD CHECK
4-1 Unplug the AC cord and connect a jumper between the two prongs on the plug.
4-2 Turn the CRT display power switch “on”.
4-3 Measure the resistance value with an ohmmeter between the jumpered AC plug and each exposed metallic part on
the CRT display such as the metal frame, screwheads, control shafts, etc. When the exposed metallic part has a
return path to the chassis, the reading should be 1.8 megohm minimum.
5. LEAKAGE CURRENT HOT CHECK
5-1 Plug the AC cord directly into the AC outlet. Do not use an isolation transformer during this check.
5-2 Connect a 1500 ohm, 10 watt resistor, paralleled by a 0.15uF capacitor between each exposed metallic part and a
good earth ground (as shown in Fig.1).
5-3 Use an AC voltmeter with 1000 ohm/volt or more sensitivity and measure the AC voltage across the
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combination 1500 ohm resistor and 0.15uF capacitor.
h
d
5-4 Move the resistor connection to each exposed metallic part and measure the voltage.
5-5 Reverse the polarity of the AC plug in the AC outlet and repeat the above measurement.
5-6 Voltage measured must not exceed 7.5 volt RMS, from any exposed metallic part to ground A leakage current
tester may be used in the above hot check, in which case any current measured must not exceed 5.0 milliamp. In
the case of a measurement exceeding the 5.0 milliamp value, a rework is required to eliminate the chance of shock
hazard.
Note： High voltage is present when this CRT display is operating. Always discharge the anode of the picture tube to the
display chassis to prevent shock hazard.
AC VOLTMETER
Fig. 1
6. IMPLOSION PROTECTION
Picture tubes are equipped with an integral implosion protection system, but care should be taken to avoid damage and
scratching during installation. Use only Panasonic replacement picture tubes.
7. X-RADIATION
WARNING：The only potential source of X-Radiation is the picture tube. However when the high voltage circuit is
operating properly there is no possibility of X-Radiation problem. The basic precaution which must be exercised is to
keep the high voltage at the following factory-recommended level.
Note
7-1 The procedure for adjusting high voltage is shown on page 12.
7-2 If can not be adjust 25.0 KV at immediate service is required to prevent the possibility of premature
component failure.
7-3 To prevent X-Radiation possibility it is essential to use the specified picture tube
It is important to use an accurate periodically calibrated high voltage meter.
IMPORTANT SAFETY NOTICE
There are special components used in this CRT displays which are
important for safety. These parts are identified by the international
symbol
list. It is essential that these critical parts should be replaced wit
manufacture’s specified parts to prevent X-RADIATION, shock, fire,
or other hazards. Do not modify the original design or this will voi
the original parts and labor guarantee.
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2. Specification
1. CRT : 46CM(19") 90 Deflection, Shadow mask ,29mm Neck, flat high contrast CRT, 0.21mm(H) / 0.25mm
(D) dot pitch, Non-Glare Screen
2. Viewable image Size: 45.7CM (18") diagonal
3. Display Color: Unlimited Colors
4. External Controls:
Power On/Off, OSD key, Function knob: Contrast, Brightness, Degauss, H-Size, H-Center, V-Center, V-Size, ZOOM,
Pincushion, Trapezoid, Pin-Balance, Parallelogram, Rotation, Color Temperature, H-Moire Reduce, V-Morie,
Memory Recall, Language, ViewMeter,OSD position select
5. Input Video Signal
Primary Preset # 1. 1600 X 1200 @ 75HZ
Primary Preset # 2. 1280 X 1024 @ 85HZ
Factory Presets
VESA 800 x 600 @ 75Hz, 85Hz MAC 1024 x 768 @ 75Hz
VESA 1024 x 768 @ 75Hz, 85Hz MAC 1152 x 870 @ 75Hz
VESA 1280 x 1024 @ 75Hz
Other Factory Presets
IND 640 x 400 @ 70Hz VGA 640 x 480 @ 60Hz
VESA 640 x 480 @ 85Hz
6. Display Size
Horizontal Display Size, Primary Preset
Horizontal Display Size, Other Presets 352 mm +/- 4 mm
Vertical Display Size, Primary Preset 264 mm +/- 4 mm
Vertical Display Size, Other Presets
Display Size Adjustment All preset modes shall expand to full screen size.
Auto Sizing +/- 8mm compare to default size and within bezel viewable area.
7. Scanning Frequencies
Horizontal: 30KHz ~ 97KHz
Vertical: 50 Hz ~ 160 Hz
8. Factory Preset Timings: 10
User Timings: 10
9. Misconvergence
A Zone: 0.25 mm Max.
B Zone: 0.35 mm Max.
352 mm +/- 4 mm
264 mm +/- 4 mm
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10. Video Bandwidth: 240 MHz
11. Power Source:
Switching Mode Power Supply
AC 90 ~264V, 50/60Hz Universal Type
12. Operating Temperature: 0°C to 40°C Ambient
13. Humidity: 5% to 95% Relative, Non-Condensing
14. Weight: 18.0 kgs / 39.7 (lbs) (Net), 21.2 kgs / 46.7 (lbs) (Gross)
15. Dimensions
Machine Package
Width:
Height:
Depth:
16. External Connection:
15 Pin D-sub Connector
AC Power Cord
17. Power Consumption Modes :
ON Mode < 75Watts
Sleep < 4Watts
Off < 2W (Power switch off)
18. Regulatiory/Safety
North America
Regulatory Filing
WW
445 mm 540 mm
424 mm(378mm w/o Base) 530 mm
465 mm 570 mm
Regulatory filing should be made under the
“VS10794”.
UL60950, cUL60950 or CSA 22.2; DHHS Part 21,
Subpart J X-Ray Protection; FCC, Part 15, Subpart
J, Subpart B;ICES-003, Class B; NOM; Argentina –
TUV/S
International
CB, TCO03 (Black);TUV/GS, TUV/Ergo,
BSMI,CCC,PSB,CE,GOST-R;ISO9241-3 7 8
（covered in TUV-ergo）
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Operating instructions
This procedure gives you instructions for installing and using the Color display.
1. Position the display on the desired operation and plug the power cord into a convenient AC outlet. Three-wire
power cord must be shielded and is provided as a safety precaution as it connects the chassis and cabinet to the
electrical conduit ground. If the AC outlet in your location does not have provisions for the grounded type plug,
the installer should attach the proper adapter to ensure a safe ground potential.
2. Connect the 15-pin color display shielded signal cable to your signal system device and lock both screws on the
connector to ensure firm grounding. The connector information is as follow:
PIN NO.
DESCRIPTION
1. RED-V 9. 5V From PC
2. GREEN-V 10. Sync GND
3. BLUE-V 11. NC
4. NC 12. SDA
5. GND 13. H- SYNC
6. GND-R 14. V- SYNC
7. GND-G 15. SCL
8. GND-B
3. Apply power to the display by turning the power switch to the "ON" position and allow about thirty seconds for
display tube warm-up. The Power-On indicator lights when the display is on.
4. With proper signals feed to the display, a pattern or data should appear on the screen, adjust the brightness and
contrast to the most pleasing display.
5. This monitor has power saving function following the VESA DPMS. Be sure to connect the signal cable to the PC.
6. If your color display requires service, it must be returned with the power cord.
1
6
11 15
5
10
15 - Pin Color Display Signal Cable
PIN NO.
DESCRIPTION
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3. Front Panel Function Control Description
Adjusting the Screen Image
Use the buttons on the front control panel to display and adjust the OSD controls .The OSD controls are explained at the top of
the next page and are defined in “Main Menu Controls” on page 8.
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OSD Lock Settings
You have the option of using the On Screen Display (OSD) locking feature, OSD LOCK, to prevent unwanted changes
to the current image settings.
• OSD Lock: Press and hold the [1] button on the face of the monitor for 10 seconds. The message "OSD LOCK" will then
display briefly, indicating that the OSD image settings are now locked.
• OSD Unlock: Press and hold the [1] button again for 10 seconds. The message "OSD UNLOCK" will then display
briefly, indicating that the OSD image settings are now unlocked.
Do the following to adjust the screen image:
1 To display the Main Menu, press button [1].
2 To select a control you want to adjust, press the arrow buttons on the front control panel of your monitor and scroll
through the choices. When the desired control is highlighted, press button [2].
NOTE: Some controls on the Main Menu are listed in pairs, such as Contrast/Brightness. Display control screen (sample
shown in step 3 below). Press button [2] to toggle to the next control in the pair.
3 To adjust the setting, such as CONTRAST in the sample below, press the arrow buttons.
4 To save the control setting and Exit the menu press button [1] twice.
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Main Menu Controls
Adjust the menu items shown below by using the up and down buttons.
Control Explanation
Contrast adjusts the difference between the image background (black level)
and the foreground (white level).
Brightness adjusts the background black level of the screen image
ZOOM expands and contracts the entire screen image
Horizontal Position moves the screen image left or right.
Horizontal Size adjusts width of the screen image.
Vertical Position moves the screen image up or down.
Vertical Size adjusts the height of the screen image.
Pincushion curves the vertical sides of the screen image.
Pin Balance curves the vertical edges of the screen image to the left or right.
Trapezoid adjusts the top and bottom of the screen image until they have equal length.
Parallel slants the vertical edges of the screen image until they are parallel.
Tilt rotates the entire screen image.
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Control Explanation
Degauss removes the build-up of magnetic fields that can cause irregular colors to
appear around the edges of screen images. There are two ways to degauss the display:
automatically by turning the monitor on, or manually by selecting the Degauss
control from the menu. With Degauss selected from the menu, press button [2] to
degauss the monitor manually.
Important: Do not degauss repeatedly. Doing so can be harmful
display. Wait at least 20 minutes (before selecting this control again.
ViewMatch® Color provides several color options: several preset color temperatures and User
Color which allows you to adjust red (R), green (G), and blue (B). The factory setting for this
product is 9300K (9300° Kelvin).
9300K — Adds blue to the screen image for cooler white (used in most office settings with
fluorescent lighting).
6500K — Adds red to the screen image for warmer white and richer red.
5000K — Adds blue and green to the screen image for a darker color.
User Color — Individual adjustments for red, green, and blue.
Moire reduces interference patterns that appear as ripples, waves, or unwanted backgroun
color textures. Interference patterns of this type are most noticeable when viewing images
having closely spaced lines or finely detailed patterns.
to the
Language allows you to choose from among several languages for the menus and
control screens: English, French, German, Italian, and Spanish.
Memory Recall returns adjustments to the original factory settings if the display is operating
in a factory preset timing mode listed in this user guide.
xception: This control does not affect changes made with the User Color control.
OSD Position allows you to move the on-screen display menus and control screens.
ViewMeter displays the frequencies (horizontal and vertical) coming from the graphics
card of the computer.
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4. Circuit Description
4-1 Micro controller and deflection circuit
MICRO Controller
The micro controller(IC101) core is a 80C51 type. The micro clock frequency of 12 Mhz is derived from the Xtal
2
oscillator,which is running at 48MHz. The DDC interface is suitable to handle DDC2 by a modified hardware I
interface .Standard high current ports,3 ADC pouts with voltage inputs and 4 static standard 8 bit DAC outputs (low
interference) and one PWM output for digital control application are implemented. The central processing unit (CPU)
manipulates operands in two memory spaces.These are the 1024byte internal data memory(consisting of 256 bytes
standard RAM and 768 bytes AUX-RAM) and 48K-byte internal program memory . The programmemory of the
SAA4849 consists of 48K bytes ROM.
The SAA4849P provides sync. Processing with full auto sync. Capability, a flexible SMPS block and an extensive
set of geometry control facilities. Further the IC generates the drive waveforms for DC coupled vertical boosters to the
TDA8172.
H/V sync signals processor
The functions of the sync processor include polarity detection, H-SYNC & V-SYNC signals counting, Programmable
SYNC signals output, free running signal generator. Pin52/Pin53 are for the H-SYNC and V-SYNC input. and the
polarity are setting in the positive. When no signal input, the Pin49 will output a 75Hz V-SYNC free run signal. The
Pin18/20will output a 60KHz H-SYNC free run signal. for the monitor testing use.
C-bus
Reset Circuit (pin23)
There are three ways possible to invoke a reset and initialize the SAA4849 micro controller part:
Via power-on reset circuit
Via watchdog timer overflow(only micro controller reset)
Via deflection reset after start up (only micro controller reset)
The reset pin(pin23) is connected to a Schmitt trigger for nose reduction. A reset is accomplished by holding the Reset pin
HIGH.
C145
22U
5V
x-ray protection
+
R153
2.7K
C102
0.1UF
RST Pin23
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The x-ray ptotection (pin22) input XRAY provides a voltage detector with a precise voltage input for X-ray
protection .If the input voltage at XRAY exceeds the upper threshold for 150us to 300us,the system is forced to shut down
by switching off vertical,H-and B-drive signals. There are two different ways to handle the system in case of XRAY
occurrence:
1. If the xray latch enable bit UCXRAY [2] was set to “0” during startup the system will shut down without any interference
of the uC. The deflection controller is set to ldle mode. Restart of the system only possible due to seitching power
off/power on.
2. If register bit UCXRAY [2] was set to “1”, micro controller interaction is allowed .If the micro controller doesn’t interrupt
the system, the system will shut down to ldle mode. For any interaction of the micro controller the XRAY occurrence has
to be acknowledged by the micro controller by clearing the bit SY-STATUS [2]. The micro controller take over the control
of the handling via software. The actual xray pin status can be read through bit SY-STATUS [1].
Quartz Oscillator (pin45, pin46)
The quartz oscillator circuit is available on pins XTAL1 (input) and XTAL2 (output) and works together with an
rd
external 48MHz 3
overtone quartz. As a result the quartz oscillator is always running on 48MHz.Other quartz crystal
frequencies than 48 MHz cannot be used. External capacitors on XTAL1 and XTAL2 are not allowed.
B+ Control Function Block
The B+control block of the SAA4849 has the same behaviour as the TDA4856 with adapted threshol voltages. The
2
circuit allows the user to choose the trigger edge of the HDRV signal and the polarity of the output stage via I
C-Bus.
The B+ control function block of the SAA4849 consists of an Operational Transconductance Amplifier (OTA), a
voltage comparator,a flip-flop and a discharge circuit. This configuration allows easy application for different B+ control
concepts.
HPLL
The horizontal part contains a PLL,which works over the full frequency range from 25kHz to 140 kHz.This range can be
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reduced by a ower and an upper frequency limit(Write Once Registers HPMAX and HPMIN).Via I
C bus the number of
48MHz clock cycles is sent through the register.The slewing speed during mode change is also programmable in a write once
register (HSLEW)
After the clocks for the HPLL are switched on,the HPLL starts with a fixed freerunning frequency of 60 kHz.The
H-drive pulses are not active and the start up procedure is inhibited.The default setting of register bit HCONTROL [0] will
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cause the HPLL to slew ,not switch.to the freerunning frequency defined in the I
C register HPFREE( the default value is also
60 kHz).Independent on H-syncs which are possibly present.the HPLL will slew to that freerunning frequency.To achieve an
always defined starting point for the startup procedure,this procedure cannot be interrupted.
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4-2 Transistor & diode circuit
Location
BD901 Bridge Rectifier for AC Source
D910 Clamp Diode for snub CKT
D919 Rectifier for Output Voltage
D922 Rectifier for Output Voltage
D923 Rectifier for Output Voltage
D930 Rectifier for Output Voltage
D918 Rectifier for Output Voltage
IC901 Power IC for Switching Power Control.
Q937, Q937 Use for Power Saving
Q912, Q920 Push-Pull Topology to Drive Q911
Q913 Degaussing Switcher Transistor
Circuit function description
IC903 5V Regulator IC
Q403 HOR. Driver Transistor
Q417,Q418,Q416,Q420 Horizontal s correction control MOSFET
Q406 Transistor for H-Size Control
Q705 Brightness Control CKT
Q742 V-Dynamic focus CKT
Q402 Q403 Driver MOSFET
Q901 MOS FET for Switching Power Control.
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5. Adjusting Procedure
5-1 Adjustment conditions and precautions
1. Approximately 30 minutes should be allowed for warm up before proceeding.
2. Adjustments should be undertaken only on those necessary elements since most of them have been carefully preset
at the factory.
5-2 Main adjustments
NO. FUNCTION LOCATION DESIGNATION
1. 14V ADJ PCB - MAIN VR903
2. B + ADJ PCB - MAIN VR902
3. SCREEN ADJ FLY BACK TRANS T402 SCREEN VR
4. FOCUS ADJ FLY BACK TRANS T402 FOCUS
VR1&VR2
5. ABL ADJ PCB - MAIN AB in factory OSD
6.
FUNCTION ADJ -MENU
PCB - MAIN (SW101)
-UP ▲ PCB - MAIN (SW102)
-DOWN ▼ PCB - MAIN (SW103)
-SELECT
5-3 Adjustment method
1. 14V, B + & HV voltage adjustment:
A. Chroma-2000 Signal generator or PC equivalent set mode 1, VGA 640X480 pattern 1.0.
B. Connect a DC Volt meter between TP901 and ground, then adjust VR903to be 14VDC.
C. Connect a DC Volt meter between TP902 and ground, then adjust VR902 to be 65.5 VDC.
PCB - MAIN (SW104)
2. Factory preset Timings Adjustment:
A. Press
B. Press the Up Key to select the "ZOOM" function, then press the MENU Key. While do not release the MENU Key
until the OSD window changed to the Factory preset window.
C. The Factory preset window contains the following functional controls. Select one of the control. Then press the
Up/Down Key to adjust its value for the optimum picture.
Key to show OSD window press Up or Down Key to switch the functional controls.
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CONTRAST
BRIGHTNESS V-LINEARITY
V-LINEARITY
HT
HG
HS
HR
HM
Hs
Hb
H-CENTER
H-SIZE
V-CENTER
V-SIZE
DEGAUSS
PINCUSHION
TRAPEZOID
PIN-BALANCE
PARALLELOGRAM
ROTATION
HC/RASTER
9300
6500
50
COLOR TEMPERATURE
COLOR TEMPERATURE
COLOR TEMPERATURE
MAX V-SIZE GAIN RANGE
R-GAIN
G-GAIN
B-GAIN
R-BIAS
G-BIAS
R-BIAS
OSD EXIT
VG
H-SIZE GAIN H-MOIRE REDUCE
SUB H-SIZE V-MOIRE REDUCE
TOP CORNER
BOTTOM CORNER
V-HV Variation rate ajust
HL
VF
H-Linearity Modify
V-FOCUS ADJUST
BURN IN TIME
TM
MAX H-SIZE RANGE
SET BURN-IN
BI
SUB H-SIZE
BOTTOM BALANCE
Bb
H-SIZE WAVE BALANCE
B+ VOLTAGE ADJUST
Bp
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