Viewsonic VA912B-3 Service Manual 1a

3

VS10931

Display

Service Manual

ViewSonic VA912/b-

Model No.

19” Color TFT LCD

( VA912/b- 3_SM Rev. 1a Oct. 2005)

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

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 10/12/05 Initial Release G. Han

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1. Precautions and Safety Notices 1

2. Specification 5

3. Front Panel Function Control Description 10

4. Circuit Description 16

5. Adjustment Procedure 18

6. Troubleshooting Flow Chart 42

7. Recommended Spare Parts List 48

8. Exploded Diagram and Exploded Parts List 53

9. Block Diagram 55

10. Schematic Diagrams 56

11. PCB Layout Diagrams 69

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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.

(11) After installation of the TFT Module into an enclosure (LCD monitor housing, for example), do not twist or

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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
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“.

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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

2-1General Specifications

Test Resolution & Frequency 1280x1024 @ 60Hz
Test Image Size Full Size

Contrast and Brightness Controls

2.2 VIDEO INTERFACE

Analog Input Connector DB-15 (Analog) , refer the appendix A
Digital Input Connector DVI-D 24pin, refer the appendix B
Default Input Connector Defaults to the first detected input
Video Cable Strain Relief Equal to twice the weight of the monitor for five minutes
Video Cable Connector DB-15 Pin out Compliant DDC 2B

Video Signals

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

Factory Default:
Contrast = 70%, Brightness = 100%

1. Video RGB (Analog)

2. DVI (Digital)
Separate

DDC 2B Compliant with Revision 1.3
Sync Compatibility Separate Sync

Video Compatibility

Resolution Compatibility

Exclusions Not compatible with interlaced video

Shall be compatible with all PC type computers,
Macintosh computers, and after market video cards
640 x 350*, 640 x 480, 720 x 400* (640 x 400*), 800 x
600, 832 x 624, 1024 x 768, 1152 x 870, 1280 x 720,
1280 x 960, 1280 x 1024

* The image vertical size might not be full screen.
But the image vertical position should be at the center.

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2-3 POWER SUPPLY

Power Supply (Adapter) Part Number: 27-D003115
Input Voltage Range 100 TO 240 VAC
Input Frequency Range 50 TO 60 HERTZ
Short Circuit Protection Output can be shorted without damage
Over Current Protection 3.3~4.5 A typical at 5 VDC
Leakage Current 3.5 mA (Max) at 254VAC / 60Hz
EFFICIENCY 80 % typical at 115 VAC Full Load
Fuse Internal and not user replaceable
Power Dissipation 58 (Max) Watt
Max Input AC Current 1.8 A rms @ 100 VAC,
INRUSH CURRENT (COLD START) 120A(max) @ 240VAC , 50Hz

Shall start and function properly when under full load,

Power Supply Cold Start

Power Supply Transient Immunity

Power Supply Line Surge Immunity

Power Supply Missing Cycle Immunity

Power Supply Acoustics

US Type Power Cable

with all combinations of input voltage, input frequency,
and operating temperature
Shall be able to withstand an EN61000-4-4 ±2KV
transient test with no damage
Shall be able to withstand ±2KV (L-L) and ±2.3KV
(L-PE) with no damage
Shall be able to function properly, without reset or visible
screen artifacts, when ½ cycle of AC power is randomly
missing at nominal input
The power supply shall not produce audible noise that
would be detectable by the user. Audible shall defined
to be in compliance with ISO 7779 (DIN EN27779:1991)
Noise measurements of machines acoustics. Power
Switch noise shall not be considered
Separate 3-prong NEMA 5-15P type plug. Length =

1.8m. Connects to display.

European Type Power Cable

CCC Type Power Cable

Power Saving Operation(Method) VESA DPMS Signaling
Power Consumption ON Mode < 58 W (max)

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Color = Black
Schuko CEE7-7 type plug.
Length = 1.8m, Connects to display.
Color = Black
Separate 3-prong type plug.
Length = 1.8m. Connects to display.
Color = Black

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ACTIVE OFF < 2 W

Recovery Time ON MODE = N/A, ACTIVE OFF < 3 SEC

2-4 ELECTRICAL REQUIREMENT

Horizontal / Vertical Frequency

Horizontal Frequency 30 – 82 KHZ
Vertical Refresh Rate 50 – 85* HZ.
Maximum Pixel Clock 135 MHz (EDID file is 140MHz)
Sync Polarity Independent of sync polarity.

Timing Table

Item Timing Analog Digital

1 640 x 350 @ 70Hz, 31.5kHz Yes Yes
2 640 x 400 @ 60Hz, 31.5kHz Yes* Ye s
3 640 x 400 @ 70Hz, 31.5kHz Yes Yes
4 640 x 480 @ 60Hz, 31.5kHz Yes Yes
5 640 x 480 @ 67Hz, 35.0kHz Yes Yes
6 640 x 480 @ 72Hz, 37.9kHz Yes Yes
7 640 x 480 @ 75Hz, 37.5kHz Yes Yes
8 640 x 480 @ 85Hz, 43.27kHz Yes Yes

9 720 x 400 @ 70Hz, 31.5kHz Ye s Yes
10 800 x 600 @ 56Hz, 35.1kHz Yes Yes
11 800 x 600 @ 60Hz, 37.9kHz Yes Yes
12 800 x 600 @ 75Hz, 46.9kHz Yes Yes
13 800 x 600 @ 72Hz, 48.1kHz Yes Yes
14 800 x 600 @ 85Hz, 53.7kHz Yes Yes
15 832 x 624 @ 75Hz, 49.7kHz Yes Yes
16 1024 x 768 @ 60Hz, 48.4kHz Yes Yes
17 1024 x 768 @ 70Hz, 56.5kHz Yes Yes
18 1024 x 768 @ 72Hz, 58.1kHz Yes Yes
19 1024 x 768 @ 75Hz, 60.0kHz Yes Yes
20 1024 x 768 @ 85Hz, 68.67kHz Yes Yes
21 1152 x 870 @ 75Hz, 68.7kHz Yes Yes
22 1280 x 1024 @ 60Hz, 63.4kHz Yes Yes
23 1280 x 1024 @ 75Hz, 79.97kHz Yes No
24 1280x 720 @ 60Hz, 45kHz (HDTV) Yes Yes

Note 1:When Vertical frequency at 85Hz or resolution, the vertical image size might not be full screen. But the

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vertical image position should be at the center.
Note2: *: The vertical image size might not be full screen.

2-5 AUDIO INTERFACE (SPEAKER SPECIFICATION)

Line input connection
Line input signal 1.0Vrms@1kHz
Line input impedance 10k ohm
Maximum power output (Electric) 2W
Signal to Noise Ratio 72db
Frequency response F0 -20kHz (F0: Lowest resonant freq.)
Distortion <8% THD @1kHz

Vibration

Screen image

Connector PC99 requirement Audio in
Cable type / length 3.5mm stereo cable / 1.8m length

Audio DPMS

3.5 mm stereo jack

There should be no audible vibration with volume at
100%. (Input signal within 1 Vrms)

There should be no affect on the screen image
stability under any conditions

Lime Green pantone # 577C

Note: There is no guarantee <1 W power
consumption in Active Off mode, when the Audio
Cable is connected

2-6 TFT LCD PANEL

Panel Source Identify

(1) ID label - The panel code “B” for CMO panel should be shown on the lower right side of ID label. (See

Figure 2)

(2) UPC label - The panel code “B” for CMO panel should be shown on the lower right side of UPC label. (See

Figure 3)

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Panel Characteristics:

Model number A190E3
Type TN type with RSDS interface
Active Size 376.32 (H) x 301.056 (V)
Pixel Arrangement RGB Vertical Stripe
Pixel Pitch 0.294 mm
GLASS TREATMENT Anti Glare (Hard coating 3H)
# OF BACKLIGHTS 4 CCFL (L type); Edge Light BLU
BACKLIGHT LIFE 50,000 Hours (min)
Luminance (Center) –
Condition:
CT = 6500K, Contrast = Max, Brightness = Max

Brightness Uniformity (13 Points)

Contrast Ratio 450 (typ), 250 (min)
Color Depth 16 million colors (6 bit + 2 bit FRC)

Viewing Angle (Horizontal)

VIEWING ANGLE (VERTI CAL)

Response Time
10%-90% @ Ta=25°C

280 cd/m2 (Typ after 15 minute warm up)
180 cd/m2 (M in after 15 minute warm up)

U = 76% (typ), 67% (Min).
U = Min Luminance in 13 points / Max Luminance in 13
points

@ CR>10
Typical: 150
Minimum: 130
@ CR>10
Typical: 130
Minimum: 110
8ms (Tr= 2 ms, Tf = 6 ms) (typ)
18 ms (Tr= 7 ms, Tf = 11 ms) (max)

@ CR>5
Typical: TBD
Minimum: TBD
@ CR>5
Typical: TBD
Minimum: TBD

Panel Defects Please see Panel Quality Specifications.

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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 which display
on the screen. The OSD controls are explained at the top of the next page and are defined in
“Main Menu Controls” on page 10.

Main Menu

with OSD controls

Displays the Main Menu or

exits the control screen and

saves adjustments.

Front Control Panel

shown below in detail

Scrolls through menu options and
adjusts the displayed control.

Also a shortcut to display the Contrast
adjustment control screen.

Displays the control screen
for the highlighted control.

Also toggles between two
controls on some screens.

Also a shortcut to toggle
analog and digital connection.

Audio Mute

button turns

the sound off

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Power light
Green = ON
Orange = Power Saving

Standby Power
On/Off

Do the following to adjust the display setting:

1. To display the Main Menu, press button [1].

NOTE: All OSD menus and adjustment screens disappear automatically after about 15

seconds. This is adjustable through the OSD timeout setting in the setup menu.

2. To select a control to adjust, pressSorTto scroll up or down in the Main Menu.

3. After the desired control is selected, press button [2]. A control screen like the one shown

below appears.

The command line at the bottom of the
control screen tells what to do next from
this screen. You can toggle between control
screens, adjust the selected option, or exit
the screen.

4. To adjust the setting, press the up S or down T buttons.

5. To save the adjustments and exit the menu, press button [1] twice.

The following tips may help you optimize your display:

• Adjust the computer's graphics card so that it outputs a 1280 x 1024 @ 60Hz video signal to
the LCD display. (Look for instructions on “changing the refresh rate” in the graphics card's
user guide.)

• If necessary, make small adjustments using H. POSITION and V. POSITION until the
screen image is completely visible. (The black border around the edge of the screen should
barely touch the illuminated “active area” of the LCD display.)

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Main Menu Controls

Adjust the menu items shown below by using the up S and down T buttons.

Control Explanation

Auto Image Adjust sizes and centers the screen image automatically.

Contrast adjusts the difference between the image background (black level)

and the foreground (white level).

Brightness adjusts background black level of the screen image.

Input Select toggles between inputs if you have more than one computer

connected to the VA912/VA912b.

Audio Adjust
Vol um e increases the volume, decreases the volume, and mutes the audio.
Mute temporarily silences audio output.

Color Adjust provides several color adjustment modes, including preset color

temperatures and a User Color mode which allows independent adjustment of
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).

6500K-Adds red to the screen image for warmer white and richer red.

5400K-Adds green to the screen image for a darker color.

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Control Explanation

5000K-Adds blue and green to the screen image for a darker color.

User Color Individual adjustments for red (R), green (G), and blue (B).

1. To select color (R, G or B) press button [2].

2. To adjust selected color, pressSandT.

Important: If you select RECALL from the Main Menu when the product is

set to a Preset Timing Mode, colors return to the 6500K factory preset.

Information displays the timing mode (video signal input) coming from the
graphics card in the computer, the LCD model number, the serial number, and
the ViewSonic® website URL. See your graphics card’s user guide for
instructions on changing the resolution and refresh rate (vertical frequency).
NOTE: VESA 1280 x 1024 @ 60Hz (recommended) means that the resolution
is 1280 x 1024 and the refresh rate is 60 Hertz.

Manual Image Adjust Sub-menu

H. Size (Horizontal Size) adjusts the width of the screen image.

H./V. Position (Horizontal/Vertical Position) moves the screen image left or

right and up or down.

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Control Explanation

Fine Tune sharpens the focus by aligning text and/or graphics with pixel
boundaries.

NOTE: Try Auto Image Adjust first.

Sharpness adjusts the clarity and focus of the screen image.

Setup Menu displays the menu shown below:

Language Select allows the user to choose the language used in the menus and

control screens.

Resolution Notice allows the user to enable or disable this notice.

If you enable the Resolution Notice shown above and your computer is set at a

resolution other than 1280 x 1024, the following screen appears.

OSD Position allows the user to move the OSD menus and control screens.

OSD Timeout sets the length of time the OSD screen is displayed. For example,

with a “30 second” setting, if a control is not pushed within 30 seconds, the
display screen disappears.

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Control Explanation

OSD Background allows the user to turn the OSD background On or Off.

Memory Recall returns the adjustments back to factory settings if the display is

operating in a factory Preset Timing Mode listed in the Specifications of this
manual.

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4. Circuit Description

Circuit Description

1. Power supply (DC/DC Converter)

The AAT1109 is a one-channel step-up PWM controller incorporating a soft-start and a short circuit protection
(SCP) function. This device consists of an on-chip voltage reference, error amplifier, pulse width modulation
controller, under -voltage lockout protection, soft-start, and
short circuit protection circuits.

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2. Micro Controller

The MTV312M micro-controller is an 8051 CPU core embedded device especially tailored for CRT/LCD Monitor
applications. It includes an 8051 CPU core, 1024-byte SRAM, 14 built-in PWM DACs , VESA DCC interface,
4-channel A/D converter , and a 64K -byte internal program FLASH-ROM.

3. TSU57AK

The TSU57AK is a high performance, and fully integrated graphics process IC solution for LCD monitors with
resolution up to SXGA. It is configured with an integrated triple-ADC/PLL, a high quality scaling engine, an
on-screen display controller, a built-in output clock generator, a panel timing controller (TCON), an integrated DVI
receiver, and RSDS display interface. To further reduce system costs, the TSU57AK also integrates intelligent power
management control capability for green-mode requirements and spread- spectrum support for EMI management.

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5. Adjusting Procedure

A. Function Test and Alignment Procedure

5.1 All Modes Reset
You should do “All Model Reset” (Refer to Chap 3. Hot Keys for Function Controls) first. This action will allow
you to erase all end-user’s settings and restore the factory defaults.

5.2 Auto Image Adjust
The Auto Adjust is aimed to offer a best screen quality by built-in ASIC. For optimum screen quality, the user
has to adjust each function manually.

A.Turn the computer and LCD monitor on.
B. Press the ‘Auto’ button on monitor keypad to Auto Adjust.

C. The LCD monitor will start the Auto Adjust process automatically and run for 10 consecutive seconds, during

which time you will notice the image change.

5.3 Firmware
Test Patten : Burn in Model (Refer to Chap3. Hot Keys for Function Control)

-Make sure the F/W is the latest version.

5.4 DCC
Test Patten: EDID program

-Make sure it can pass test program.

5.5 Window Shut Down
Test Signal: 1280*1024@60Hz
Test Pattern:

Checkered Pattern Every One Pixel (50%Green & 50%Blue)
Inspection Item: Flicker, Mura

5.6 Window BG
Test Signal: 1280*1024@60Hz
Test Pattern:

Window standard pattern
Inspection Item: Line Defect, Function Defect & Mura

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