ViewSonic Va703b3 Service Manual

							
 8 
ViewSonic Corporation
  Confidential - Do Not Copy  VA703b-3_VA703m-3 
Factory Defaults 
Item Defaults  Item Defaults 
Contrast 70%  Volume 50% (
 for VA703m only )
Brightness 100%  Balance N/A 
Color Temperature  6500K  Treble  N/A 
Sharpness 0% Bass N/A 
OSD H. Position 50%  720x400/640x400  720x400 
OSD V. Position 50% 640x480@60Hz 
720x480@60Hz  640x480@60Hz 
OSD Time Out 
15 Sec 
In SOG and Composite, 
720x480@60Hz 
640x480@60Hz  N/A
 
OSD Background  Enabled 
In SOG and Composite, 
1152x864@75Hz 
1152x870@75Hz  N/A
 
Resolution Notice  Enabled 
In SOG and Composite, 
1280x768@60/75/85Hz 
1024x768@60/75/85Hz
  N/A
 
 
 
AUDIO INTERFACE (SPE AKER SPECIFICATION) --- (  for VA703m only ) 
 
Line input connection  3.5 mm stereo jack 
Line input signal 1.0Vrms 
Line input impedance >10 kOhm 
Maximum power output (Electric)  1 W @ < 8% distortion 
Signal to Noise Ratio  50 dB 
Frequency response 500 Hz – 20 Khz 
Distortion  < 8 % THD (@1kHz) 
Vibration There should be no audible vibration with 
volume at 100%. (Input signal within 
1.0 
Vrms) 
Screen image  There should be no affect on the screen 
image stability under any conditions 
Connector PC99 requirement Audio in  Lime Green pantone # 577C 
Cable type / length 
3.5mm stereo cable / 1.8m length 
Audio DPMS Note: There is no guarantee 
						

							
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TFT LCD PANEL 
 
1st  Panel Source  INN MT170EN01 V7 
Type TN, 
LVDS 
Active Size  337.92 mm (H) x 270.336mm (V) 
Pixel Arrangement RGB Vertical Stripe 
Pixel Pitch  0.264 mm 
Glass Treatment Anti Glare (Hard coating 3H) 
# of Backlights 4 CCFL edge-light  
Backlight Life  50,000 Hours (Min) 
Luminance –Condition: CT = 6500 K 
Contrast = Max, Brightness = Max 280
 cd/m2 (Typ after 30 minute warm up) 
250  cd/m2 (Min after 30 minute warm up) 
Brightness Uniformity  80%(typ) / 75 % (min) 
Contrast Ratio 600 :1 (Typ), 500 :1 (Min) 
Color Depth Vertical)  16.2 million colors (6+2 bit panel) 
Viewing Angle (Horizontal)  150 deg (Typ)@ CR>10 / 170 deg (Typ)@ CR>5 
Viewing Angle (Vertical) 135 deg (Typ) @ CR>10 / 155 deg (Typ)@ CR>5 
Response Time 
10%-90% @ Ta=25°C 8 ms (Tr= 2 ms, Tf = 6 ms) (Typ) 
16 ms (Tr= 4 ms, Tf = 12 ms) (max) 
Panel Defects 
Please see Panel Quality Specifications. 
 
2nd   Panel Source CPT CLAA170EA07Q 
Type TN, 
LVDS 
Active Size  337.92 mm (H) x 270.336mm (V) 
Pixel Arrangement RGB Vertical Stripe 
Pixel Pitch  0.264 mm 
Glass Treatment Anti Glare (Hard coating 3H) 
# of Backlights 4 CCFL edge-light  
Backlight Life  40,000 Hours (Min) @7mA 
Luminance –Condition: CT = 6500 K 
Contrast = Max, Brightness = Max 290
 cd/m2 (Typ after 30 minute warm up) 
250  cd/m2 (Min after 30 minute warm up) 
Brightness Uniformity  72%(typ) / 70 % (min) 
Contrast Ratio 500 :1 (Typ), 400 :1 (Min) 
Color Depth Vertical)  16.2 million colors (6+2 bit panel) 
Viewing Angle (Horizontal)  140 deg (Typ)@ CR>10 / 170 deg (Typ)@ CR>5 
Viewing Angle (Vertical) 130 deg (Typ) @ CR>10 / 170 deg (Typ)@ CR>5 
Response Time 
10%-90% @ Ta=25°C 8 ms (Tr= 3 ms, Tf = 5 ms) (Typ)  
16 ms (Tr= 6 ms, Tf = 10 ms) (max) 
Panel Defects 
Please see Panel Quality Specifications. 
 
3rd   Panel Source INN MT170EN01 V9 
Type TN, 
LVDS 
Active Size  337.92 mm (H) x 270mm (V) 
Pixel Arrangement RGB Vertical Stripe 
Pixel Pitch  0.264 mm 
Glass Treatment Anti Glare (Hard coating 3H) 
# of Backlights 4 CCFL edge-light  
Backlight Life  50,000 Hours (Min) 
Luminance –Condition: CT = 6500 K 
Contrast = Max, Brightness = Max 300
 cd/m2 (Typ after 30 minute warm up) 
250  cd/m2 (Min after 30 minute warm up) 
Brightness Uniformity  80%(typ) / 75 % (min) 
Contrast Ratio 800 :1 (Typ), 600 :1 (Min) 
Color Depth Vertical)  16.7 million colors (6+2 bit panel) 
Viewing Angle (Horizontal)  160 deg (Typ)@ CR>10 / 170 deg (Typ)@ CR>5 
Viewing Angle (Vertical) 160 deg (Typ) @ CR>10 / 170 deg (Typ)@ CR>5 
Response Time 
10%-90% @ Ta=25°C 5 ms (Typ) / 10 ms (max) 
Panel Defects 
Please see Panel Quality Specifications. 
  
						

							
  
ViewSonic Corporation
  Confidential - Do Not Copy  VA703b-3_VA703m-3 
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
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 Auto Image Adjust.Power light
Green = ON
Orange = Power Saving
Standby Power 
On/Off
Displays the
Main Menu or exits the
control screen and saves
adjustments.
10 
						

							
 
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Do the following to ad just 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, press SorT to scroll up or down in the Main Menu.
3. After the desired control is se lected, press button [2]. A cont rol screen like the one shown 
below appears.
4. To adjust the control, 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 computers graphi cs card so that it outputs a 1280 x 1024 @ 60Hz video signal to
the LCD display. (Look for instructions on “cha nging the refresh rate” in the graphics cards
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 “act ive area” of the LCD display.)
The line at the bottom of the screen shows
the current functions of buttons 1 and 2:
Exit or select the Brightness control.
11 
						

							
 
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12
Main Menu Controls
Adjust the menu items shown below by using the up  S and down  T buttons.
Control Explanation
Auto Image Adjust  automatically sizes, centers, a nd fine tunes the video signal 
to eliminate waviness and distortion. Pr ess 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
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 wh ich 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 industr y standard for color management, 
with support being included in many of th e latest applications. Enabling this 
setting allows the LCD display to more  accurately display colors the way they 
were originally intended. Enabling the sRGB  setting will cause the Contrast and 
Brightness adjustment s 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. 
						

							
 
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13
Control Explanation
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, press Sand T.
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 (vid eo signal input) coming from the 
graphics card in the computer, the LC D 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  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. 
						

							
 
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14
Control Explanation
Fine Tune  sharpens the focus by aligning te xt 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 th e 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 fa ctory 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 ch anges made with the User Color 
control, Language Select or Power Lock setting. 
						

							
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4. Circuit Description 
 
2.1 Switching Mode Power Supply 
2.1.1 AC Current Input Circuit
 
P801 is a connector for connecting AC Power. F801 is a fu se to protect all the circuit. AC input voltage is from 
90V to 264V. R820 and R821 joined between two inputting main  circuit to prevent man from shock. L801 is used to 
clear up low frequency wave. C801 and C806 are used  to discharge the waves that L801 produced. High 
frequency waves are damped by C801 and C806. D801 is a re ctifier which composed of 4 build-in diodes, it inverts 
AC to DC.   
2.1.2 High Voltage to Low  Voltage Control Circuit 
C805 is used to smooth the wave from rectifier. IC802  is a highly integrated PWM controller, which build-in a 
power MOSFET. When rectified DC high voltage is applied to  the DRAIN pin during start-up, the MOSFET is off 
initially, and the CONTROL pin capacitor is charged th rough a switched high voltage current source connected 
internally between the DRAIN and CONTROL pins. When the CONTROL pin voltage Vc reaches approximately 
5.8V, the control circuitry is activated and the soft-start begins. The soft-start circuit  gradually increases the duty 
cycle of the MOSFET from zero to the maximum value over approximately 10ms. If no external feedback/supply 
current is fed into the CONTROL pin by the end of the so ft-start, the high voltage current source is turned off and 
the CONTROL pin will start discharging in response to  the supply current drawn by the control circuitry. 
Resistor R803, R807, R824 and R825 are for line over voltage shut-down (OVP) and line under-voltage 
detection (UVP).Resistors R801, R805, R822, and R823 ar e for external current limit adjustment, and used to 
reduce the current limit externally to a value close to  the operating peak current of primary about 1.35A. The mean 
is power will protected when the pr imary current over about 1.35A.   
When PWM is turned off, the main cu rrent flow will be consumed through D804 and ZD 802, This will prevent 
MOSFET which built-in IC802 from being damaged under large current impulse and voltage spike. 
D806 and C815 provide internal Auxiliary current to CO NTROL pin during normal operation. In addition, error 
amplifier and feedback current to the CO NTROL pin are for duty cycle control. 
 
2.1.3  DC_5V and DC_14V Output Circuit
 
For DC 5V, D805 is used to rectify the inducted current.  R806 and C811 are used to store energy when current 
is reversed. The parts including C 812, C814, C822, C821, B801 and L803 are  used to smooth the current waves. 
For DC 14V, D803 is used to rectify the inducted curr ent. R802 and C802 are used to store energy when 
current is reversed. The parts including C808, C810  and L802 are used to smooth the current waves. 
 
2.1.4 Feedback and OVP Protect Circuit
 
Pin R of IC803 is supplied 2.5V stable voltage. It  is connected to 5V and 14V output through R811, 
R810 and R818. R811, R810 and R818 are output sampli ng resistor. When the sampling voltage more 
than 2.5V or less than 2.5V, feedback current of IC802 will change, this can change the voltage from 
transformer T801.   
Q802, R827, R828 and ZD801 make up of dummy loading circuit. For start- up sequence, during 5V 
output take place high loading first, this dummy loadi ng circuit operated to insure 14V not be increased. 
 
2. 2 Inverter Circuit  
2.2.1 Low voltage to high voltage circuit 
 
14VDC provides the power for IC501; the control si gnals Brightness and ON/OFF come from I/F board. 
ON/OFF signal connect to pin10 of IC501 and makes IC501 enable. Brightness signal connect to pin4 of IC501 
and regulates the panel brightness, R526, R529, C505 make  up a network of delaying time circuit and R523, R524 
make up a divided voltage network, C504 is used to dump noise. The operation frequency is determined by the 
external Resistor R522 and capacitor C529 connec ted to pin13 of IC501. BURST MODE regulated dimming 
frequency is determined by the external resistor R527  and capacitor C506 connected to pin11 of IC501. C508 is 
used for soft start and compensation, C507, C505 are used for dump noise.    The output drives, include DRV1, DRV2 (pins1,15 respecti vely) output square pulses to drive MOSFET U501, 
U502, and each of U501, U502 , is consist of a N channel  MOSFET. U501,OR U502 work as Push-Pull- topology, it 
is high efficient, PWM switching.   
During start up, VSEN (pin6) senses  the voltage at the transformer secondary. When VSEN reaches 3.0V, the 
output voltage is regulated. If no current is se nsed approximately 2seconds IC501 shut off.    
						

							
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The current flowing through CCFL is sensed and regula ted through sense resistor R509, R534. The feedback 
voltage connected to Pin5 (ISEN), then compared with a refere nce voltage (1.5V) via a current amplifier, resulting in 
PWM drive outputs to PUSH-PULL switches.
  
 
2.2.2 Protection  circuit 
 
Over Voltage Protection and over-current protection are monitored by  the voltage on VSEN(Pin 6) During 
normal operation , if a CCFL is damaged or removed ,the  voltage    at VSEN (Pin6) increases .Once the voltage at 
VSEN exceeds 2.0V (OVPT Setting) the driver output duty  cycle is regulated and the shutdown delay timer is 
activated.OVPT set the overall protec tion threshold voltage that is lower than 3V (VSEN threshold). Once the 
voltage at TIMER pin reached about 3v ,the IC will shut  down and latch .R501, R503,C525,C527 are connected in 
high voltage output connector, the divided AC voltage is inverted DC voltage through D503, 
D504,D507,D508 ,R530 and C516are used to rectify wa ve & dump noise. Then the voltage signal reaches Pin6 
VSEN of IC501, when the voltage changes, build-i n PWM of IC501 will adjust output voltage.   
Open Lamp Protection: In normal oper ation, R509 are sensed a high level DC    voltage,If a CCFL is removed 
or damaged during normal ,the voltage at SSTCMP(Pin12)  rises rapidly .when the voltage at SSTCMP reaches a 
threshold of approximately 2.5V,a current source charges  the capacitor(C511)connected to TIMER(Pin3).Once the 
voltage level at the TIMER pin reaches a threshold of  approximately 3v,The drive outputs shut down and latch.  
 
2.3 I/F Board Circuit  
2.3.1 Power  Input
 
+5V is from the power board and supply for U101(LD1117AL-3.3V) ﹑U102(LD1117AL-1.8V)﹑U105(TSUM16AL) 
and panel. +3.3V output is generated from +5V through C102  and C104 filtering, and U101 outputs. +3.3V is used 
for U105 (MCU & Scaler: TSUM16AL). +1.8V output  is generated from +3.3V through C166, C105 and C106 
filtering, and U102 outputs. +1.8V is only used for U105. 
 
2.3.2 MCU & Scaler(TSUM16AL) 
The frequency of XTAL1 is 14.318MHz. U105 # 48 is defi ned as panel-enable. When the I/O port is high, Q101 and 
Q103 are conducted. And then after C108 and C109 filteri ng, obtain the voltage of VLCD, which will be connected 
to CN104. U105 # 85 is defined as CCFL-enable. When the I/O port is low, Q106 is pulled up and the backlights 
are on; When the I/O port is high, Q106 is conducted and t he backlights are off. U105 # 35 is defined as DET-VGA, 
connected with CN103 #5. U105 # 84 is a pin of hardwire reset. U105 # 54-# 55,# 58-# 65, # 67-# 74, # 77-# 78 
output LVDS digital data of 8 bit to panel control circ uit through CN104. U105 # 86 generates a PWM waveform by 
regulating the duty to control the brightness of the backlights.   
U103 is EEPROM used for saving EDID  data, which is connected by SCL and SDA pins with # 31 and # 30 of 
TSUM16AL. 
U104 is a flash memory, U104 # 2, # 1, # 6, # 5 are the communications with U105 # 37-# 40. 
U108 is EEPROM used for saving user’s OSD setting. U108 is connected by SCL and SDA pin with # 44 and # 43 
of TSUM16AL.   
 
2.3.3 VGA  Input 
Signal R, G, B input through CN103 #1, #2, #3, and C112, C113 and C114 filtering the high frequency noise. Signal 
HSYNC and VSYNC input through CN103 #13  and #14, and C125, R137, C126, R136 filtering. Then the analog 
signal enters U105, and then U104 deals with it intern ally. In addition, TVS101, TVS102, TVS103, TVS104 (the 
four are BAV99), ZD101, ZD105, ZD106, ZD107, ZD108(th ey are constant voltage diode of 5V6) are ESD 
protector. Signal DDC-SCL inputs via CN103 #15, and then  passes through ZD101 for ESD protection, goes into 
EDID EEPROM IC U103. Signal DDC-SDA inputs via  CN103 #12, and then passes through ZD107 for ESD 
protection, goes into EDID EEPROM IC U103. CN103 #5 is defined as cable  detect pin, this detector realizes via 
R124 and U105 # 35,The PC-5V of U103 is supplied by PC via CN103 #9 with D103 for ESD protection, or 
supplied by Monitor self via D103.U103 is an EEPROM IC, which is a kind of memory and used for saving EDID 
data.  
 
2.3.4 Button  Control 
Button “Key-Power” is defined as power on/off, whic h is connected to U105 # 90 through CN105 # 6. 
Button “Key-2” is defined as two functions of selecting and adjustment, which is connected to U105 #94 through 
CN105 # 5. 
Button “Key-Up” is defined as plus, which is connected to U105 # 95 through CN105 # 8. 
Button “Key-Down” is defined as minus, which  is connected to U105 # 99 through CN105 # 7. 
Button “Key-1” is defined as two functions of menu and ex it, which is connected to U105 # 89 through CN105 # 4. 
LED indicator on the front bezel is defined as follows: 
a. When press button “Key-Power”, U105 # 91 is pulled  down and U105 # 92 is pulled high, so Q102 is conducted 
and the LED indicator is green. 
b. When in power-saving mode, U105 # 91 is pulled high  and U105 # 92 is pulled down, so Q105 is conducted and 
the LED indicator is orange. 
  
						

							
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  Confidential - Do Not Copy  VA703b-3_VA703m-3 
 
 
3. FACTORY PRESET TIMING TABLE 
 
TIMING FH(KHz) 
FV(Hz) 
Sync 
Polarity 
Total 
(Dot/Line)
Active 
(Dot/Line)
Sync Width 
(Dot/Line)
Back Porch 
(Dot/Line) 
Pixel 
Freq.(MHz)
31.469 +  800  640  96  48 640*350@70Hz 
70.086 −  449 350  2  60  25.175 
31.469 
−  800 640  96  48 IBM 
640*400@70Hz 
70.086 + 449 400  2  35  25.175 
31.469 
−  900 720  108 54 IBM 
720*400@70Hz 
70.087 +  449 400  2  35  28.322 
24.700 
−  800 640  96  48 640*480@50Hz 
50.000 −  494 480  2  8  19.760 
31.469 
−  800 640  96  40 VESA 
640*480@60Hz 
59.940 −  525 480  2  25  25.175 
35.000 
−  864 640  64  96 640*480@67Hz 
66.667 −  525 480  3  39  30.240 
37.861 
−  832 640  40  120 VESA 
640*480@72Hz 
72.809 −  520 480  3  20  31.500 
37.500 
−  840 640  64  120 VESA 
640*480@75Hz 
75.000 −  500 480  3  16  31.500 
43.269 
−  832 640  56  80 VESA 
640*480@85Hz 
85.008 −  509 480  3  25  36.000 
35.156 + 
1024 800  72  128 VESA 
800*600@56Hz 
56.250 +  625 600  2  22  36.000 
37.879 + 
1056 800  128  88 VESA 
800*600@60Hz 
60.317 +  628 600  4  23  40.000 
48.077 + 
1040 800  120  64 VESA 
800*600@72Hz 
72.188 +  666 600  6  23  50.000 
46.875 + 
1056 800  80  160 VESA 
800*600@75Hz 
75.000 +  625 600  3  21  49.500 
53.674 +  1048 800  64  152 VESA 
800*600@85Hz 
85.061 +  631  600  3  27  56.250 
49.725 
−  1152 832  64  224 MAC 
832*624@75Hz 
74.550 −  667 632  3  39  57.283 
48.363 
−
 
1344 1024  136 160 VESA 
1024*768@60Hz 
60.004 −
 
806 768  6 29 65.000 
56.476 
−
 
1328 1024 136  144 VESA 
1024*768@70Hz 
70.069 −
 
806 768 6  29  75.000 
60.023 +  1312 1024 96  176 VESA 
1024*768@75Hz 
75.029 +  800  768  3  28  78.750 
68.677 +  1376 1024 96  208 VESA 
1024*768@85Hz 
84.997 +  808  768  3  36  94.500 
57.700 
− 1360 1024 136  144 1024*768@72Hz 
72.125 − 800  768  6  26  78.472 
67.500 
+ 
1600 1152 128  256 VESA 
1152*864@75Hz 
75.000 + 
900 864 3  32  108.000 
MAC 
68.681 −
 
1456 1152 128  144  100.000