ViewSonic VA721-2 User manual

Model No. VLCDS 27998-5W
17” Color TFT LCD Display
Service Manual
ViewSonic VA721-2
ViewSonic
381 Brea Canyon Road, Walnut, California 91789 USA - [phone]
(VA721-2_SM Rev. 1a Jan. 2006)

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
Revision
SM Editing Date
ECR Number
Description of Changes Editor
1a 01/24/2006 Initial release Jamie Chang
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TABLE OF CONTENTS
1. Precautions and Safety Notices 1
2. Specification 5
3. Front Panel Function Control Description 8
4. Circuit Description 14
5. Adjustment Procedure 24
6. Troubleshooting Flow Chart 47
7. Recommended Spare Parts List 49
8. Exploded Diagram and Exploded Parts List 51
9. Block Diagram 54
10. Schematic Diagrams 56
11. PCB Layout Diagrams 62
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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. LCDModule 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 CMOSLSI isusedinthis 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.
1. Precautions and Safety Notices
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(11) After installation of theTFT Module intoan enclosure(LCDmonitor 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 theTFT 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 fordisposal.
(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 theCCFL to a HazardousVoltage Circuit.
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Correct methods : Incorrect Methods :
5. Handling Methods
Only touch the metal frame of the panel or the front
cover of the monitor.
Do not touch the surface of the polarizer .
If the surface of the panel is pressed by fingers, this
may cause "MURA."
Take out the monitor by grasping the cushion. If the monitor is removed 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 .
If the monitor is placed on foreign objects,
that could scratch the surface of the panel.
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•General Specifications
Test Resolution & Frequency 1280 x 1024 @ 60Hz
Test Image Size Full Size
Contrast and Brightness Controls Factory Default: Contrast = 70%, Brightness =
100%
•Video Interface
Analog Input Connector DB-15 (Analog)
Video Cable Strain Relief Equal to twice the weight of the monitor for five
minutes.
Video Cable Connector DB-15 Pinout Compliant DDC 2B.
Video Signals Video RGB (Analog)
Video Impedance 75 Ohms (Analog)
Maximum PC Video Signal 950 mV with no damage to monitor
Maximum Mac Video Signal 1250 mV with no damage to monitor
Sync Signals TTL
DDC 1/2B Compliant with Revision 1.3
Video Compatibility Shall be compatible with all PC type computers,
Macintosh computers, and after market video
cards.
Resolution Compatibility 640 x 350, 640 x 480, 720 x 400 (640 x 400), 800 x
600, 832 x 624, 1024 x 768, 1280 x 720, 1280 x
1024
Exclusions Not compatible with interlaced video.
•Power Supply
Internal Power Supply Part Number: ADP-40AFB
Input Voltage Range 90 TO 264 VAC
Input Frequency Range 47.5 TO 63 HERTZ
Short Circuit Protection Output can be shorted without damage.
Over Current Protection 4.5 A typical at 12 VDC
Leakage Current 3.5mA (Max) at 254VAC / 60Hz
EFFICIENCY 70 % typical at 115VAC Full Load
Fuse Internal and not user replaceable
Power Dissipation 35 Watts (typ)
Max Input AC Current 1.2 Arms @ 90VAC, 0.8 Arms @180VAC
2. Specification
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•Horizontal / Vertical Frequency
Horizontal Frequency 30 – 80 KHZ
Vertical Refresh Rate 50 –85 HZ.
Maximum Pixel Clock 135 MHz
Sync Polarity Independent of sync polarity.
Primary Presets
Primary Preset 1280 x 1024 @ 60Hz
Look up table timing
<<Analog>>
1. 640 x 350 @ 70Hz, 31.5kHz
2. 640 x 480 @ 60Hz, 31.5kHz
3. 640 x 480 @ 67Hz, 35.0kHz
4. 640 x 480 @ 75Hz, 37.5kHz
5. 640 x 480 @ 72Hz, 37.9kHz
6. 640 x 480 @ 85Hz, 43.27kHz
7. 720 x 400 @ 70Hz, 31.5kHz
8. 800 x 600 @ 56Hz, 35.1kHz
9. 800 x 600 @ 60Hz, 37.9kHz
10. 800 x 600 @ 75Hz, 46.9kHz
11. 800 x 600 @ 72Hz, 48.1kHz
12. 800 x 600 @ 85Hz, 53.7kHz
13. 832 x 624 @ 75Hz, 49.7kHz
14. 1024 x 768 @ 60Hz, 48.4kHz
15. 1024 x 768 @ 70Hz, 56.5kHz
16. 1024 x 768 @ 72Hz, 58.1kHz
17. 1024 x 768 @ 75Hz, 60.0kHz
18. 1024 x 768 @ 85Hz, 68.67kHz
19. 1280 x 1024 @ 60Hz, 63.4kHz
20. 1280 x 1024 @ 75Hz, 79.97kHz
21. 1280x720 @ 60Hz, 45kHz (HDTV)
Changing Modes
Maximum Mode Change Blank Time, for
image stability. Note:
1) Excluding “Auto Adjust” time
2) Under DOS mode (640 x 350, 720 x 400 & 640 x
400), there is no “Auto Adjust” feature.
3) The monitor needs to do “Auto Adjust” the first
time a new mode is detected.
3 seconds (Max)
1 seconds (Typ) for recognized timings
1-2 seconds (Typ) for unrecognized timing
.
Mode Change Image The image shall blank while the monitor changes
modes.
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1. ID Label -The panel code “Q” for QDI / “C” for CPT, it should be shown on the lower right
side.
2. UPC Label -The panel code “Q” for QDI / “C” for CPT, it should be shown on the lower
right side
3. Main Board -The panel code “Q” for QDI / “C” for CPT, it should be shown on the main
board by F/W version sticker
Panel Characteristics:
Panel Source CPT CLAA170EA 07Q
Type TN, LVDS
Active Size 337.9 mm (H) x 270.3mm (V)
Pixel Arrangement RGB Vertical Stripe
Pixel Pitch 0.264 mm
Glass Treatment Anti Glare (Hard coating 3H)
# of Backlights 4CCFL edge-light
Backlight Life (Hours) 30,000 (Min)
Luminance –Center Point (CT=6500K)
Contrast/Brightness=Max 300 cd/m2 (Typ after 30 minute warm up) 250 cd/m2 (Min after 30 minute warm up)
Brightness Uniformity (5 points ,the
location follows up CPT spec) 75% min
Contrast Ratio 500 :1 (Typ), 450 :1 (Min)
Color Depth Vertical) 16.2 million colors
Viewing Angle (Horizontal, typ)140 deg @CR>10 / 170 deg @ CR>5
Viewing Angle (Vertical, typ)130 deg @ CR>10 / 160 deg @ CR>5
Response Time
10%-90% @ Ta=25°C 8ms (Typ) 12 ms (Max)
Panel Defects Please see Panel Quality Specifications.
Panel Source QDI QDI17EL0709
Type TN, dual LVDS
Active Size 337.9 mm (H) x 270.3mm (V)
Pixel Arrangement RGB Vertical Stripe
Pixel Pitch 0.264 mm
Glass Treatment Anti Glare (Hard coating 3H)
# of Backlights 4CCFL edge-light
Backlight Life (Hours) 40,000 (Min)
Luminance –Center Point (CT=6500K)
Contrast/Brightness=Max 260 cd/m2 (Typ after 30 minute warm up) 200 cd/m2 (Min after 30 minute warm up)
Brightness Uniformity (5 points ,the
location follows up CPT spec) 80%(typ) / 75% (min)
Contrast Ratio 500 :1 (Typ), 300 :1 (Min)
Color Depth Vertical) 16.2 million colors
Viewing Angle (Horizontal, typ)140 deg @CR>10
Viewing Angle (Vertical, typ)125 deg @ CR>10
Response Time
10%-90% @ Ta=25°C 8ms (Typ)
Panel Defects Please see Panel Quality Specifications.
•LCD Panel
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