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Service Manual
ViewSonic VX7501
Model No. VLCDS27089-1W
17" Color TFT LCD Display




(VX750_SM_755 Rev. 1a Apr. 2004)

ViewSonic 381 Brea Canyon Road, Walnut, California 91789 USA - (800) 888-8583
Copyright

Copyright 2004 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 Date Description Of Changes Approval
1a 04/27/04 Initial Release DCN-3772 Angela Lu




ViewSonic Corporation Confidential - Do Not Copy VX750
i
TABLE OF CONTENTS


1. Precautions and Safety Notices 1

2. Specification 2

3. Front Panel Function Control Description 3

4. Circuit Description 9
5. Adjusting Procedure 21
6. Trouble Shooting Flow Chart 38

7. Recommended Spare Parts List 46

8. Exploded Diagram And Spare Parts List 51
9. Block Diagram 53
10. Schematic Diagrams 56

11. PCB Layout Diagrams 64




ViewSonic Corporation Confidential - Do Not Copy VX750
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1. Precautions and Safety Notices


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 line


2. Safety Check :
Care should be taken while servicing this LCD display, due to the high voltage used in the inverter circuit.
High voltage is exposed in such areas as the associated transformer circuits .


3. POWER SUPPLY REQUIREMENTS
The external power converter for this display utilizes AC and DC cords. The AC cord is detachable , but the
DC cord is permanently attached . Any attempt to replace another adapter could result in damage to the display .


4. LEAKAGE CURRENT HOT CHECK
4-1 Plug the AC cord directly into the AC outlet. Do not use an isolation transformer during this check.
4-2 Connect a 1500 ohm , 10 watt resistor , paralleled with a 0.15uF capacitor between each metallic part
and a good earth ground
4-3 Use an AC voltmeter with 1000 ohm / volt or more sensitivity and measure the AC voltage across the
combination 1500 ohm resistor and 0.15uF capacitor.
4-4 Move the resistor connection to each exposed metallic part and measure the voltage.
4-5 Reverse the polarity of the AC plug in the AC outlet and repeat the above measurement.
4-6 Voltage measured must not exceed 1.5 volt RMS, from any exposed metallic part to the ground. A leakage
current tester may be used in the above hot check, in which case any circuit measured must not exceed 1.0
milliamp. In the case of a measurement exceeding the 1.0 milliamp value, a rework is required to eliminate the
chance of a shock hazard .



AC VOLTMETER



V

0.15u
.

To Metal Parts 1500 10W Earth Ground




ViewSonic Corporation Confidential - Do Not Copy VX750
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2. Specification


Mechanical :
Dimension ( W x H x D ) mm
Set a. with stand: 502 x 405 x 195 mm
b. Without stand: 502 x 340 x 63 mm
Base (L X W): 275 x 195 mm
Packing : ( W x H x D ) mm: 572 x 491 x 240 mm
Weight : Net / Gross ( Kg ): 5.6 / 8.2
Wall Mount (VESA): 100 x 100 mm
LCD Panel type: QDI / QD17EL07
Max. resolution (HxV) : 1280 x 1024
Nominal picture size (HxV): 338 mm x 270 mm
Display colors: 16.2 M ( 6 bit + dithering )
Dot pitch: 0.264 mm
Response time: 4 +12 / 16ms (Tr + Tf / typical)
Brightness (100% white) : Typical : 270 cd/m