ViewSonic Va1903wb2 Service Manual

							 
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ViewSonic Corporation              
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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 display, then lower the video refresh rate 
to 60 Hz and set the resolution to its pre-set value. 
 
Contrast adjusts the difference between the image background (black level) 
and the foreground (white level).
 
 Brightness adjusts background black level of the screen image.  
 
Audio Adjust（For VA1903wm only） 
Vo l u m 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).   
 
sRGB-This is quickly becoming the industry standard for color management, 
with support being included in many of the latest applications. Enabling this 
setting allows the LCD display to more accurately display colors the way they 
were originally intended. Enabing    the intended. Enabling the sRGB setting 
will cause Contrast and Brightness adjustments to be disabled. 
 
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. 
User Color Individual adjustments for red (R), green (G), and blue (B).    
						

							 
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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 
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 1024 x 768 and the refresh rate is 60 Hertz.   
 
 Manual Image Adjust displays the Manual Image Adjust 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.   
 
Fine Tune sharpens the focus by aligning text and/or graphics with pixel 
boundaries.  
						

							 
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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 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 “15 second” setting, if a control is not pushed within 15 
seconds, the display screen disappears. 
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. 
Exception: This control does not affect changes made with the User Color 
control, Language Select or Power Lock setting. 
  
 
  
						

							 
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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] + [▲] 
 OSD Lock 
No signal + [2] + [] Burning mode 
Signal + [2] + [] Factory mode 
Remark : All the short cuts function are only available while OSD off 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
  
						

							 
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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 
convert DC circuit and so on. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Power Board 
(Include: adapter, inverter)
Flat Panel and 
CCFL backlight
Main Board 
Key Board 
RS232 Connector 
For white balance 
adjustment in factory 
mode 
HOST Computer 
CCFL Drive. 
AC-IN 
100V-240V 
Video signal, DDC 
Monitor Block Diagram 
R 
G 
B 
H 
V 
SDA 
SCL 
OSC 
Backlight and Panel 
PWPC board 
EPROM EPROM Keyboard 
 
 
TSUM16AL-1  
						

							 
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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 12v DC of power supply to about 600-800v AC that drives the backlight. It mostly 
consists of starting circuit, PWM controller, DC changing circuit, LC surging circuit, 
output circuit and protection circuit etc. 
 
 
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
AC input EMI filter 
Bridge 
Rectifier 
and Filter 
Start Circuit 
R931, R904,R938 
PWM 
Control IC Over 
Vo l ta g e  
Protect 
Rectifier 
CMOS 
ON/OFF 
Control PWM 
Control ICFeedback 
Circuit 
OSC and 
Output 
Circuit DC Convert 
Circuit MOSFET 
Q805,Q806 
Over 
Voltage 
CN902 
Transformer
 
 
Lamp 5V 
12V 
ON/OF 
DIM  
						

							 
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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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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, 100MHz in fast read mode and the bottom 4Kbyte sector into four smaller 
1 Kbyte sectors features(except Pm25LV512A), The devices use a single low 
voltage, ranging from 2.7 Volt to 3.6 Volt, power supper to perform read, erase  Pin Symbol  Description 
37  SDO  SPI flash serial data output 
38  CSZ  SPI flash chip select 
39  SCK  SPI flash serial select 
40  SDI  SPI flash serial data input 
30  DDCA_SDA/RS232_TX DDC data for analog interface; 4mA driving 
strength/UART transmitter/GPIO 
31  DDCA_SDA/RS232_RX DDC data for analog interface/UART 
transmitter/GPIO 
84 RST Chip reset; High reset 
87  RSTN  Chip reset; Low reset 
81 VCTRL Regulator control 
27  HSYNCO  Analog HSYNC input 
28 VSYNCO Analog VSYNC input 
26  REFP  Internal ADC top de-coupling pin 
25  REFM  Internal ADC bottom de-coupling pin 
15 REXT 
External resistor 390 ohm to AVDD＿ADC 
86  PWM1/GPIO_P25  Pulse Width Modulation Output; 4mA driving 
strength/General Purpose Input/Output; 4mA 
driving strength 
93  PWM0  Pulse Width Modulation Output; 4mA driving 
strength/General Purpose Input/Output; 4mA 
driving strength 
80  BYPASS  For External Bypass Capacitor 
96  XIN  Xin; Crystal Oscillator Input 
97  XOUT  Xout; Crystal Oscillator Output 
8、14、24 AVDD＿ADC ADC Power 3.3V 
16 
AV D D＿PLL PLL Power 3.3V 
98 
AV D D＿MPLL MPLL Power 3.3V 
32、49、56、
75 VDDP  Digital Output Power 3.3V 
34、51、66、
82 VDDC Digital Core Power 1.8V  
						

							 
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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 device is not selected, data will not 
be accepted via the serial input pin (SI), and the serial 
output pin (SO) will remain in a high impedance state. 
SO  OUTPUT  Serial Data Output 
WP#  INPUT  Write Protect A hardware program/erase protection for all or 
partial of memory array. When the WP# pin is pulled t low, 
whole or partial of memory array is write protected depends 
on the setting of BP2, BP1 and BP0 bits in the Status 
Register, When the WP# is pulled high, the devices are not 
write protected. 
GND  Ground 
Vcc    Device Power Supply 
HOLD#  INPUT  Hold: Pause serial communication with the master device 
without resetting the serial sequence. 
SCK INPUT Serial Data Clock 
SI INPUT Serial Data Input  
						

							 
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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