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Service Manual
ViewSonic VA912/b-1
Model No. VS10696
19" Color TFT LCD Display
(VA912/b_SM Rev. 1a Apr. 2005)
ViewSonic 381 Brea Canyon Road, Walnut, California 91789 USA - (800) 888-8583
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 warranties, either expressed or implied, with respect 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
Documents Number
Revision SM Editing Date Description of Changes Editor
DCN Number ECR Number
1a 04/14/05 5246S Initial Release A. Lu
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TABLE OF CONTENTS
1. Precautions and Safety Notices 1
2. Specification 5
3. Front Panel Function Control Description 18
4. Circuit Description 24
5. Adjustment Procedure 27
6. Troubleshooting Flow Chart 42
7. Recommended Spare Parts List 47
8. Exploded Diagram and Spare Parts List 62
9. Block Diagram 76
10. Schematic Diagrams 78
11. PCB Layout Diagrams 88
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1. Precautions and Safety Notices
1. Appropriate Operation
(1) Turn off the product before cleaning.
(2) Use only a dry soft cloth when cleaning the LCD panel surface.
(3) Use a soft cloth soaked with mild detergent to clean the display housing.
(4) Use only a high quality, safety approved AC/DC power cord.
(5) Disconnect the power plug from the AC outlet if the product will not be used for a long period of time.
(6) If smoke, abnormal noise, or strange odor is present, immediately switch the LCD display off.
(7) Do not touch the LCD panel surface with sharp or hard objects.
(8) Do not place heavy objects on the LCD display, video cable, or power cord.
(9) Do not use abrasive cleaners, waxes or solvents for your cleaning.
(10) Do not operate the product under the following conditions:
- Extremely hot, cold or humid environment.
- Areas containing excessive dust and dirt.
- Near any appliance generating a strong magnetic field.
- In direct sunlight.
2. 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 guidelines.
3. Safety Check
Care should be taken while servicing this LCD display. Because of the high voltage used in the inverter circuit, the voltage is
exposed in such areas as the associated transformer circuits.
4. LCD Module Handling Precautions
4.1 Handling Precautions
(1) Since front polarizer is easily damaged, pay attention not to scratch it.
(2) Be sure to turn off power supply when connecting or disconnecting input connector.
(3) Wipe off water drops immediately. Long contact with water may cause discoloration or spots.
(4) When the panel surface is soiled, wipe it with absorbent cotton or other soft cloth.
(5) Since the panel is made of glass, it may break or crack if dropped or bumped on hard surface.
(6) Since CMOS LSI is used in this module, take care of static electricity and ensure human earth when handling.
(7) Do not open or modify the Module Assembly.
(8) Do not press the reflector sheet at the back of the module in any direction.
(9) In the event that a Module must be put back into the packing container slot after it was taken out of the
container, do not press the center of the CCFL Reflector edge. Instead, press at the far ends of the
CFL Reflector edge softly. Otherwise the TFT Module may be damaged.
(10) At the insertion or removal of the Signal Interface Connector, be sure not to rotate or tilt the Interface
Connector of the TFT Module.
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(11) After installation of the TFT Module into an enclosure (LCD monitor housing, for example), do not twist or
bend the TFT Module even momentarily. When designing the enclosure, it should be taken into consideration
that no bending/twisting forces may be applied to the TFT Module from outside. Otherwise the TFT Module
may be damaged.
(12) The cold cathode fluorescent lamp in the LCD contains a small amount of mercury. Please follow local
ordinances or regulations for disposal.
(13) The LCD module contains a small amount of materials having no flammability grade. The LCD module
should be supplied with power that complies with the requirements of Limited Power Source
(IEC60950 or UL1950), or an exemption should be applied for.
(14) The LCD module is designed so that the CCFL in it is supplied by a Limited Current Circuit (IEC60950
or UL1950). Do not connect the CCFL to a Hazardous Voltage Circuit.
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Correct methods : Incorrect Methods :
Only touch the metal-frame of the panel or the front cover Surface of the panel is pressed by fingers & this may
of the monitor. cause " MURA "
Do not touch the surface of the polarizer .
Take out the monitor with cushion Take out the monitor by grasping the LCD panel.
That may cause " MURA".
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Correct Methods : Incorrect Methods :
Place the monitor on a clean & soft foam pad . Place the monitor on foreign objects .
That could scratch the surface of panel
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2. Specification
VA912 Specifications (for Analog)
Chapter 1 General Descriptions
FEATURES VA912-2
Size 19"
Luminance (Typ, cd/) 300 cd/
Contrast Ratio (Typ) 800:1
TFTLCD PANEL Colors ( 6 bit + 2 bit FRC) 16.2 M colors
Response Time (Typ) 20 ms
Viewing Angle (H/V) 170