ViewSonic VA702-3, VA702b-3, VLCDS27998-3W, VLCDS27998-4W Service Manual

ViewSonic VA702-3

VA702b-3

Model No. VLCDS27998-3W

VLCDS27998-4W

17” Color TFT LCD Display

(VA702-3_VA702b-3_SM Rev. 1a May 2006)

ViewSonic 381 Brea Canyon Road, Walnut, California 91789 USA – [phone]

Service Manual

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Copyright

Copyright © 2006 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

Opt quest 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 05/02/2006 Initial Release J. Chang

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TABLE OF CONTENTS

1. Precautions and Safety Notices 1

2. Specification 3

3. Front Panel Function Control Description 7

4. Circuit Description 9

5. Adjustment Procedure 17

6. Troubleshooting Flow Chart 40

7. Recommended Spare Parts List 42

8. Exploded Diagram and Exploded Parts List 45

9. Block Diagram 49

10. Schematic Diagrams 51

11. PCB Layout Diagrams

57

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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. Because of the high voltage used in the
inverter circuit. These voltage are 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 , AC cord is detachable , but

DC cord is permanently attached . Any attempt to replace another adapter could result in serious
problem on 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 by 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 .

To Metal Parts

V

AC VOLTMETER

1500 10W

0.15u
.

Earth Ground

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Handling & Placing method

Correct methods : Incorrect Methods :

Only touch the metal-frame of the panel or the front
cover of the monitor .Do not touch the surface of the
polarizer .

Surface of the panel is pressed by fingers & this may
cause “ MURA “

Take out the monitor with cushion

Take out the monitor by grasping the LCD panel.
That may cause “ MURA“.

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

GENERAL REQUIREMENTS

General Specifications

Test Resolution & Frequency

1280 x 1024 @ 60Hz

Test Image Size Full Size
Contrast and Brightness Controls Factory Default: Contrast = 70%, Brightness = 100%

SIGNAL INTERFACE

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

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

36 WATTS (MAX)

Max Input AC Current

1.2 ARMS @ 90VAC, 0.8 ARMS @180VAC

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ELECTRICAL REQUIREMENTS

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>>
640 x 350 @ 70Hz, 31.5kHz
640 x 480 @ 60Hz, 31.5kHz
640 x 480 @ 67Hz, 35.0kHz
640 x 480 @ 75Hz, 37.5kHz
640 x 480 @ 72Hz, 37.9kHz
640 x 480 @ 85Hz, 43.27kHz
720 x 400 @ 70Hz, 31.5kHz
800 x 600 @ 56Hz, 35.1kHz
800 x 600 @ 60Hz, 37.9kHz
800 x 600 @ 75Hz, 46.9kHz
800 x 600 @ 72Hz, 48.1kHz
800 x 600 @ 85Hz, 53.7kHz
832 x 624 @ 75Hz, 49.7kHz
1024 x 768 @ 60Hz, 48.4kHz
1024 x 768 @ 70Hz, 56.5kHz
1024 x 768 @ 72Hz, 58.1kHz
1024 x 768 @ 75Hz, 60.0kHz
1024 x 768 @ 85Hz, 68.67kHz
1280 x 1024 @ 60Hz, 63.4kHz
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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LCD Panel

1st Source Panel

QD17EL0711

Type

NORMALLY WHITE, TN, OPTICAL COMPENSATION FILM

Active Size 337.920 (H) x 270.336 (V)
Pixel Arrangement RGB Vertical Stripe
Pixel Pitch 0.264 mm

Glass Treatment ANTI GLARE
# of Backlights 4 CCFL EDGE-LIGHT (2 TOP / 2 BOTTOM)
Backlight Life 50,000 HOURS (TYP) / 40,000 HOURS (MIN)

Luminance –
Condition:
CT = 6500K, Contrast = Max, Brightness = Max

260 CD/M2 (TYP AFTER 30 MINUTE WARM UP)
220 CD/M2 (MIN AFTER 30 MINUTE WARM UP)

Brightness Uniformity 75 % Entire Area (minimum)
Contrast Ratio 500:1 (Typ), 300:1 (Min)
Color Depth 16 million colors (6 bit panel)
Viewing Angle (Horizontal) 140 deg @ CR>10, 160 deg @ CR>5

Viewing Angle (Vertical)

125 deg @ CR>10, 145 deg @ CR>5

Response Time
10%-90% @ Ta=25°C

8 ms (Tr= 6 ms, Tf = 2 ms) (Typ)

TBD ms (Tr= TBD ms, Tf = TBD ms) (Max)

Panel Defects Please see Panel Quality Specifications.

MECHANICAL

Dimensions (Base attached unless otherwise specified)

Width

377.6 mm

Height

374.0 mm

Depth

195.6 mm

Depth (Head Only)

55.0 mm

Monitor Weight

4.1 kg / 9.0 lbs

Packaging Specification

Width

450 mm
Height

522 mm
Depth

135 mm
Gross Weight

5.2 kg (11.45 lb)

# units per Pallet

36/72 (air/sea)
20’/40’ Container Loading, Palletized

720/1728 pieces

Ergonomics

Tilt Up

20 DEGREES MINIMUM
Tilt Down

-5 degrees

Swivel Right

0 degrees
Swivel Left

0 degrees
Height Adjust

0 mm
Pivot

0 DEGREES (CLOCKWISE)

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ENVIRONMENTAL

Environmental Conditions

Operating Temperature 0°C to +40°C
Storage Temperature -20°C to +60°C
Operating Relative Humidity 20% to 90% RH Non-Condensing
Storage Relative Humidity 5% to 90% RH Non-Condensing
Operating Altitude 0 to +3,000 meters
Storage Altitude 0 to +12,000 meters

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3. Front Panel Function Control Description

Main Menu
With On View controls

Front Control Panel
shown below in detail

Power On / Off Displays the Main Menu or
exits the control screen
and saves adjustments.

Displays the control screen for the
highlighted control. Also toggles
between two controls on some screens.
Also a shortcut to auto image adjust

Power light
Green = ON
Orange=power

saving

Scrolls through menu options and
adjusts the displayed control.
Also a shortcut to display the
Contrast adjustment control screen.

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ViewSonic VE702/b -3

Main Menu Controls

Adjust the menu items shown below by using the up and down buttons.
A. Auto Image Adjust automatically sizes, centers, and fine tunes the video signal to eliminate waviness and distortion.

Press the [2] button to obtain a sharper image.

NOTE: Auto Image Adjust works with most common video cards. If this function does not work on your LCD display,
then lower the video refresh rate to 60 Hz and set the resolution to its pre-set value.

B. Contrast adjusts the difference between the image background (black level) and the foreground (white level).
C. Brightness adjusts the lamps current to control the screen brightness.
D. Color Adjust provides several color options: preset color temperatures and Custom User Color which allows you to adjust

red (R), green (G), and blue (B). The factory setting for this product is 6500K (6500° Kelvin).

9300K — Adds blue to the screen image for cooler white (used in most office settings with fluorescent lighting).
5400K — Adds red to the screen image for warmer white and richer red.
Custom User Color — Individual adjustments for red, green, and blue.
1 To select color (R, G or B) press button [2].

2 To adjust selected color, press p or q .

3 When you are finished making all color adjustments, press button [1] twice.

E. Information displays the timing mode (video signal input) coming from the graphics card in your computer. See your

graphic card’s user guide for instructions on changing the resolution and refresh rate (vertical frequency). VESA 1280 x
1024 @ 60 Hz (recommended) means that the resolution is 1280 x 1024 and the refresh rate is 60 Hertz.

F. Manual Image Adjust controls are explained below:
H. Size (Horizontal Size) adjusts the width of the screen image.
NOTE: Vertical size is automatic with your LCD display.
H./V. Position adjusts horizontal and vertical position of the screen image. You can toggle between Horizontal and

Vertical by pressing button [2]. Horizontal moves the screen image to the left or to the right. Vertical moves the screen image
up and down.

Fine Tune sharpens focus by aligning the illuminated text and/or graphic characters.
Sharpness adjusts the clarity and focus of the screen image.
Setup Menu controls are explained below:
Language allows you to choose the language used in the menus and control screens.
Resolution Notice displays the recommended resolution for this LCD display.
Enable allows the Resolution Notice to appear on-screen.
Disable will not allow the Resolution Notice to appear on-screen.
OSD Timeout sets the length of time an on-screen display screen is displayed. For example, with a“15 second”

setting, if a control is not pushed within 15 seconds, the display OSD disappears.

G. OSD Position allows you to move the on-screen display menus and control screens.
H. 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.

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4. Circuit Description

1. Outline

1.1 POWER On/Off , LED, Button"2" , Up arrow- button , Down arrow button , Button"1" , button , Down arrow button ,

Button"1" , on the front panel.

1.2 Video signal connector, and AC-IN are located on the back side of the cabinet.

1.3 OSD menu includes the following function;

AUTO IMAGE ADJUST
CONTRAST / BRIGHTNESS
COLOR ADJUST
INFORMATION
MANUAL IMAGE ADJUST
SETUP MENU
MEMORY RECALL

1.4 CONTRAST and BRIGHTNESS can be directly controlled with UP / DN key.
.

2. CONNECTORS

2.1 AC inlet : CEE22 typed connector

2.2 Video signal connector 14P + Mini D-Sub

PIN

MNEMONI

SIGNAL

1RVRed Video

2GVGreen Video

3BVBlue Video

4NCNone

5

GND

Ground(DDC return)

6RGRed GND

7GGGreen GND

8BGBlue GND

9

+5V

+ 5V (for DDC)

10SGSync GND

11NCNone

12

SDA

DDC Data

13HSHorizontal Sync

14VSVertical Sync

15

SCL

DDC Clock

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3. ELECTRICAL SPECIFICATIONS

3.1 Standard conditions

Display Area

338 x 270 mm

Video Signal

0.7 Vpp

Contrast

70%

Brightness

Max.

Ambient

20 +/- 5 °C

Input

AC

Warming up

> 30 min

Display

1280 x 1024

3.2 POWER

3.2.1 Power supply

Input Voltage 90 -240 ~Volts
Power Frequency
Input current

50/ 60 Hz +/-3Hz
<1.5Arms @ 90Vac

<0.75Arms@240Vac
Inrush current 90A(max.) at 230Vac
Power consumption 50Watt
Output Voltage @0-3.0A load 12Vdc +/-5%

3.2.2 Power Management

State Power Indicator

On 36Watt Green

Standby <1Watt Amber

Off <1Watt

3.3 Acceptable timing

If your timing is within following specification, this LCD display can automatically function with a certain position.
Horizontal: Sync frequency : 30~81 kHz
Vertical: Sync frequency : 56~85Hz(1280x1024,75Hz)

3.4 Signal level and input impedance

3.4.1 Video Signal level This LCD display is adjusted at the factory using 0,7 Vp-p Video signal.

3.4.2 Sync Signal level

H/V Separate : TTL level

3.4.3 Input impedance
Video input : 75 ohms
Sync input : > 1 k ohms

4. SIGNAL CABLE : Signal cable with Mini D-Sub 15P connectors at both ends. Length : 1.8 meter.

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5. EDID data
QDI QD17EL07 v11

VA702-3

Time: 15:03:33
Date: Wed Oct 19, 2005
______________________________________________________________________
______________________________________________________________________
VIEWSONIC CORPORATION
EDID Version # 1, Revision # 3
DDCTest For: ViewSonic VA702-3SERIES
______________________________________________________________________
______________________________________________________________________
EDID Block 0, Bytes 0-127
128 BYTES OF EDID CODE:
0 1 2 3 4 5 6 7 8 9
________________________________________
0 | 00 FF FF FF FF FF FF 00 5A 63
10 | 1D B5 01 01 01 01 01 0F 01 03
20 | 08 22 1B 78 2E 59 95 A4 57 47
30 | 9C 24 15 50 54 BF EF 80 81 80
40 | 81 40 71 4F 61 59 45 59 31 59
50 | 01 01 01 01 30 2A 00 98 51 00
60 | 2A 40 30 70 13 00 52 0E 11 00
70 | 00 1E 00 00 00 FF 00 51 35 4B
80 | 30 35 30 31 30 30 30 30 31 0A
90 | 00 00 00 FD 00 32 55 1E 52 0E
100 | 00 0A 20 20 20 20 20 20 00 00
110 | 00 FC 00 56 41 37 30 32 2D 33
120 | 53 45 52 49 45 53 00 92
______________________________________________________________________
(08-09) ID Manufacturer Name ________________ = VSC
(11-10) Product ID Code _____________________ = B51D
(12-15) Last 5 Digits of Serial Number ______ = Not Used
(16) Week of Manufacture _________________ = 01
(17) Year of Manufacture _________________ = 2005
(10-17) Complete Serial Number ______________ = See Descriptor Block
(18) EDID Version Number _________________ = 1
(19) EDID Revision Number ________________ = 3
(20) VIDEO INPUT DEFINITION:
Analog Signal

0.700, 0.300 (1.000 Vp-p)
Separate Syncs
(21) Maximum Horizontal Image Size ________________ = 340 mm
(22) Maximum Vertical Image Size __________________ = 270 mm
(23) Display Gamma ________________________________ = 2.20
(24) Power Management and Supported Feature(s):
Active Off/Very Low Power, Standard Default Color Space,
Preferred Timing Mode
Display Type = R/G/B Color
(25-34) CHROMA INFO:
Red X - 0.642 Green X - 0.279 Blue X - 0.143 White X - 0.313
Red Y - 0.341 Green Y - 0.610 Blue Y - 0.083 White Y - 0.329
(35) ESTABLISHED TIMING I:
720 X 400 @ 70Hz (IBM,VGA)
640 X 480 @ 60Hz (IBM,VGA)
640 X 480 @ 67Hz (Apple,Mac II)
640 X 480 @ 72Hz (VESA)
640 X 480 @ 75Hz (VESA)
800 X 600 @ 56Hz (VESA)
800 X 600 @ 60Hz (VESA)
(36) ESTABLISHED TIMING II:
800 X 600 @ 72Hz (VESA)
800 X 600 @ 75Hz (VESA)
832 X 624 @ 75Hz (Apple,Mac II)
1024 X 768 @ 60Hz (VESA)
1024 X 768 @ 70Hz (VESA)
1024 X 768 @ 75Hz (VESA)
1280 X 1024 @ 75Hz (VESA)
(37) Manufacturer's Reserved Timing:
1152 X 870 @ 75Hz (Apple,Mac II)

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(38-53) Standard Timing Identification:
1280 X 1024 @60Hz
1280 X 960 @60Hz
1152 X 864 @75Hz
1024 X 768 @85Hz
800 X 600 @85Hz
640 X 480 @85Hz
Not Used
Not Used
______________________________________________________________________
(54-71) Detailed Timing / Descriptor Block 1:
1280x1024 Pixel Clock: 108.00 MHz
______________________________________________________________________
Horizontal Image Size: 338 mm Vertical Image Size: 270 mm
Refreshed Mode: Non-Interlaced Normal Display - No Stereo

Horizontal:
Active Time: 1280 pixels Blanking Time: 408 pixels
Sync Offset: 48 pixels Sync Pulse Width: 112 pixels
Border: 0 pixels Frequency: 63.98 KHz

Vertical:
Active Time: 1024 lines Blanking Time: 42 lines
Sync Offset: 1 lines Sync Pulse Width: 3 lines
Border: 0 lines Frequency: 60.02 Hz

Digital Separate, Horizontal Polarity (+) Vertical Polarity (+)
______________________________________________________________________
(72-89) Detailed Timing / Descriptor Block 2:

Monitor Serial Number:
Q5K050100001
______________________________________________________________________
(90-107) Detailed Timing / Descriptor Block 3:

Monitor Range Limits:
Min Vertical Freq - 50 Hz
Max Vertical Freq - 85 Hz
Min Horiz. Freq - 30 KHz
Max Horiz. Freq - 82 KHz
Pixel Clock - 140 MHz
Secondary GTF - Not Supported
______________________________________________________________________
(108-125) Detailed Timing / Descriptor Block 4:

Monitor Name:
VA702-3SERIES
(126) No Extension EDID Block(s)
(127) CheckSum OK

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VA702b-3

Time: 15:33:23
Date: Wed Oct 19, 2005
______________________________________________________________________
______________________________________________________________________
VIEWSONIC CORPORATION
EDID Version # 1, Revision # 3
DDCTest For: ViewSonic VA702-3SERIES
______________________________________________________________________
______________________________________________________________________
EDID Block 0, Bytes 0-127
128 BYTES OF EDID CODE:
0 1 2 3 4 5 6 7 8 9
________________________________________
0 | 00 FF FF FF FF FF FF 00 5A 63
10 | 1D B5 01 01 01 01 01 0F 01 03
20 | 08 22 1B 78 2E 59 95 A4 57 47
30 | 9C 24 15 50 54 BF EF 80 81 80
40 | 81 40 71 4F 61 59 45 59 31 59
50 | 01 01 01 01 30 2A 00 98 51 00
60 | 2A 40 30 70 13 00 52 0E 11 00
70 | 00 1E 00 00 00 FF 00 51 35 4C
80 | 30 35 30 31 30 30 30 30 31 0A
90 | 00 00 00 FD 00 32 55 1E 52 0E
100 | 00 0A 20 20 20 20 20 20 00 00
110 | 00 FC 00 56 41 37 30 32 2D 33
120 | 53 45 52 49 45 53 00 91
______________________________________________________________________
(08-09) ID Manufacturer Name ________________ = VSC
(11-10) Product ID Code _____________________ = B51D
(12-15) Last 5 Digits of Serial Number ______ = Not Used
(16) Week of Manufacture _________________ = 01
(17) Year of Manufacture _________________ = 2005
(10-17) Complete Serial Number ______________ = See Descriptor Block
(18) EDID Version Number _________________ = 1
(19) EDID Revision Number ________________ = 3
(20) VIDEO INPUT DEFINITION:
Analog Signal

0.700, 0.300 (1.000 Vp-p)
Separate Syncs
(21) Maximum Horizontal Image Size ________________ = 340 mm
(22) Maximum Vertical Image Size __________________ = 270 mm
(23) Display Gamma ________________________________ = 2.20
(24) Power Management and Supported Feature(s):
Active Off/Very Low Power, Standard Default Color Space,
Preferred Timing Mode
Display Type = R/G/B Color
(25-34) CHROMA INFO:
Red X - 0.642 Green X - 0.279 Blue X - 0.143 White X - 0.313
Red Y - 0.341 Green Y - 0.610 Blue Y - 0.083 White Y - 0.329
(35) ESTABLISHED TIMING I:
720 X 400 @ 70Hz (IBM,VGA)
640 X 480 @ 60Hz (IBM,VGA)
640 X 480 @ 67Hz (Apple,Mac II)
640 X 480 @ 72Hz (VESA)
640 X 480 @ 75Hz (VESA)
800 X 600 @ 56Hz (VESA)
800 X 600 @ 60Hz (VESA)
(36) ESTABLISHED TIMING II:
800 X 600 @ 72Hz (VESA)
800 X 600 @ 75Hz (VESA)
832 X 624 @ 75Hz (Apple,Mac II)
1024 X 768 @ 60Hz (VESA)
1024 X 768 @ 70Hz (VESA)
1024 X 768 @ 75Hz (VESA)
1280 X 1024 @ 75Hz (VESA)
(37) Manufacturer's Reserved Timing:
1152 X 870 @ 75Hz (Apple,Mac II)
(38-53) Standard Timing Identification:
1280 X 1024 @60Hz
1280 X 960 @60Hz

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1152 X 864 @75Hz
1024 X 768 @85Hz
800 X 600 @85Hz
640 X 480 @85Hz
Not Used
Not Used
______________________________________________________________________
(54-71) Detailed Timing / Descriptor Block 1:
1280x1024 Pixel Clock: 108.00 MHz
______________________________________________________________________
Horizontal Image Size: 338 mm Vertical Image Size: 270 mm
Refreshed Mode: Non-Interlaced Normal Display - No Stereo

Horizontal:
Active Time: 1280 pixels Blanking Time: 408 pixels
Sync Offset: 48 pixels Sync Pulse Width: 112 pixels
Border: 0 pixels Frequency: 63.98 KHz

Vertical:
Active Time: 1024 lines Blanking Time: 42 lines
Sync Offset: 1 lines Sync Pulse Width: 3 lines
Border: 0 lines Frequency: 60.02 Hz

Digital Separate, Horizontal Polarity (+) Vertical Polarity (+)
______________________________________________________________________
(72-89) Detailed Timing / Descriptor Block 2:

Monitor Serial Number:
Q5L050100001
______________________________________________________________________
(90-107) Detailed Timing / Descriptor Block 3:

Monitor Range Limits:
Min Vertical Freq - 50 Hz
Max Vertical Freq - 85 Hz
Min Horiz. Freq - 30 KHz
Max Horiz. Freq - 82 KHz
Pixel Clock - 140 MHz
Secondary GTF - Not Supported
______________________________________________________________________
(108-125) Detailed Timing / Descriptor Block 4:

Monitor Name:
VA702-3SERIES
(126) No Extension EDID Block(s)
(127) CheckSum OK

6. THEORY OF OPERATION

This section describes the function of the LCD monitor per functional block.
This monitor includes MB board, power board and button board.

6.1 MB BOARD
The MB board is a two-layer, single-landed design with ground and internal planes provided. DC power from the power board enter
the board through a 6P connector. Other connector on the board is for button board .The VGA cable is a signal cable that contains
video signal, sync signal and DDC signal from PC VGA adapter. This system board consists of 4 functional areas : flat panel
controller, MCU with flash ROM , power regulator .

6.1.1 Flat panel controller… MST8111A (U3)
The heart of the system board is MStart MST8111A. The MST8111A is a graphics processing IC for LCD monitor. It
provides all key IC functions required for LCD panel. On-chip functions include a high-speed triple-ADC , PLL, high scaling
engine, OSD controller.

a) Clock Generation :

Crystal Input Clock (TCLK and XTAL). This is the input pair to an internal crystal oscillator and corresponding logic. A

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14.318 MHz crystal is recommended.

b) Analog to Digital Converter:

The MST8111A chip has three ADC's (analog -to-digital converters), one for each color (red, green and blue) .The analog
RGB signals are connected to MST8111A as described below

Pin Name Pin Number

Red + 63
Red - 62
Green + 60
Green - 59
Blue + 58
Blue - 57

c) OSD : The MST8111A has a fully programmable ,high-quality OSD controller. The on-chip static RAM(4096 words by 24 bits)

stores the cell map and the cell definitions.

d) MTV312 Micro controller: The MTV312 micro controller(MCU) serves as the system micro controller. It’s programs the

MST8111A and manages other devices in the system such as the keypad, the backlight, LED, audio and non-volatile RAM.
using general purpose input/output (GPIO) pins.

Pin number Pin Name Pin Number Usage

21 P1.3 Key / Power on ,off
13 P3.4 NV_RAM (U4) SDA
14 P3.5 NV_RAM (U4) SCL
25 P1.7 Key_down
9 P6.3 Key_right
24 P1.6 Key_up
16 P6.2 Key_left
37 P4.1 Key_mute
34 P5.6 VGA connector
23 P1.5 Key_select
42 P5.3 LED_red
41 P5.4 LED_green
32 P6.6 LCD panel power1 on / off control
3 P5.0 LCD panel power2 on / off control
36 P4.0 Backlight on / off control

e) Panel Power Sequencing ( VDDCTRL1, 2) ( Pin 32, 3) : The MTV312 has two dedicated outputs VDDCTRL1 and 2

( Pin32 and Pin3) to control LCD power sequencing once data and control signals are stable.

f) Panel interface (Pin 1~25, Pin75~128) : The MTV312 driver interface is highly programmable. It supports dual bus / dual port

for SXGA drivers.

6.1.2 Power Regulator MC34063A (U6),AIC1739 (Q4) : The MC34063A is a monolithic control IC containing the primary functions
required for DC to DC converters. The device consists of an internal temperature compensated reference, comparator, controlled
duty cycle.

ViewSonic Corporation Confidential - Do Not Copy VA702-3_VA702b-3

16

Oscillator with an active current sense circuit. Desired output voltage are determined by the equation,
Volt = 1.25 ( 1 + R67 / R66), In this case, the output voltage are 3.3 Volts
The AIC1739 is a low dropout positive adjustable regulator with minimum of 300mA output current capability.
So it is well suited for 3.3 V and 2.5 V Regulator.

6.1.3 Power Regulator MC34063A (U7) : The MC34063A is a monolithic control IC containing the primary functions required for DC
to DC converters. The device consists of an internal temperature compensated reference, comparator, controlled duty cycle.

Oscillator with an active current sense circuit. Desired output voltage are determined by the equation,
Volt = 1.25 ( 1 + R85 / R86), In this case, the output voltage are 5.0 Volts for panel power.

6.2 Power(Inverter) Board
This is a specific power(inverter) power board for VA702-3 monitor 40W 12V 3.5A output power and backlight which
converters 12 Vdc to drive four cold cathode fluorescence tubes.

6.2.1 Inverter Electrical specification described as below.

Rated Input Voltage 12Vdc
Input Voltage Range 11.4 ~ 12.6 Vdc
Input Current <2A

Input

On / Off control Voltage 2~3.3 for on , 0~1 for off
Rated Output Strike-on Voltage 1500Vrms
Rated Output Voltage 710Vrms at 7mA
Rate Output Frequency 40~50KHz

Output

Rated Ourput Current 7~8 mA

6.2.2 power
This is a general purpose AC / DC adapter which converter 90~240 Vac to a stabilized DC voltage 12 V with rated output
current of 4.16A . Electrical specification described as below.

Rated Input Voltage 90~240 Vac , 50 / 60Hz
Operation Input Voltage 90~260 Vac , 47 ~ 63Hz
Input Current <1.5A
Inrush Current <100A@120Vac
Standby Input Voltage 12Vdc
Output Voltage Regulation +/-5%
Output Ripple & Noise 120mVp-p
Rate Output Current <3.5A
Turn-on delay <3secs