ViewSonic Va1903wb2 Service Manual

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
Main Menu Controls  
Adjust the menu items shown below by using the up 
 and down  buttons.  
Control
 Explanation 
 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...

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
1. To select color (R, G or B) press button [2].   
2. To adjust selected color, press 
▼ and ▲. 
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...

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
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 displays the Resolution Notice menu shown below.   
 
Resolution Notice advises the optimal resolution to use. 
OSD Position allows the...

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
SHORT CUTS FUNCTION FROM THE BUTTONS 
 
[1] 
Main Menu 
[2] 
Input toggle（Analog or Digital；refer to Appendix D） 
[▼]  
Contrast adjust 
[▲] 
Contrast adjust 
[▼] + [▲] 
recall both of Contrast and Brightness to default 
[1] + [2] toggle 720x400 and 640x400 mode when input 720x400 
or 640x400 mode 
[1] + [▼] + [▲]    White Balance (Not shown on user’s guide) 
[1] + [▼] 
Power Lock 
[1] + [▲]...

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
4. Circuit Description 
       4.1  LCD MONITOR DESCRIPTION 
   The LCD MONITOR will contain a Main Board, an Power Board, Key Board which 
house the flat panel control logic, brightness control logic and DDC. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
      
 
 
 
 
 
 
4.2    MAIN BOARD BLOCK FUNCTION DESCRIPTION 
 
   The main board contains panel control logic, brightness control logic, DDC and DC...

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
4.3 PWPC BOARD BLOCK FUNCTION DESCRIPTION 
  PWPC board combines to adapter and inverter, Adapter which commonly consists 
of bridge rectifier and filter, start circuit, PWM control circuit, protection circuits and 
convert to 12V, 5V DC voltage by input 90V-240V AC voltage that provide power supply 
for each chips in the main board and inverter. Inverter is DC TO AC circuit. It changes 
the...

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
4.4 INTRODUCTION OF IC 
TSUM16AL-1(U401): integrate ADC, OSD, SCALER, MCU, LVDS, convert analog RGB 
into digital and room and shrink scaling output to LCD panel. 
Pin Diagram: 
  

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
PIN Function:  
 
AP1117E33LA (U701): DC power convert, used to 5v convert 3.3v. 
 
AP1117E18LA(U702): DC power convert, used to 5v convert 1.8v. 
 
Pm25LV512A/010A/020/040(U402): The PM25LV010 are 512 Kbit/1 Mbits/2 Mbit/4  
Mbit3.0 Volt-only Serial Peripheral Interface(SPI) Flash memories. The devices 
are designed to support 33MHz fastest clock rate in the industry in normal read 
mode,...

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
and program operations. The devices can be programmed in standard EPROM 
programmers as well. 
 
Pin Diagram: 
 
PIN Descriptions:  
 
Circuit Diagram Symbol Type  Description 
CE#  INPUT  Chip Enable: CE# goes low activates the device’s internal 
circuitries for device operation. CE# goes high deselects the 
device and switches into standby mode to reduce the power 
consumption. When the...

 
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ViewSonic Corporation              
 Confidential - Do Not Cop                      VA1903wb/VA1903wm 
 
 
TDA7496L(U201): The TDA7496L is a stereo 2W+2W class AB power amplifier, 
specially designed for high quality sound, TV and Monitor applications. 
Features of the UTC TDA7496L include linear volume control, Stand-by and 
mute functions. The function of each pin and the inside circuit diagram are 
as follows: 
Block Diagram