ViewSonic VA702-3 Service Manual page 17

1152 X 864 @75Hz
1024 X 768 @85Hz
800 X 600 @85Hz
640 X 480 @85Hz
Not Used
Not Used
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(54-71) Detailed Timing / Descriptor Block 1:
1280x1024 Pixel Clock: 108.00 MHz
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Horizontal Image Size: 338 mm
Refreshed Mode: Non-Interlaced
Horizontal:
Active Time: 1280 pixels
Sync Offset: 48 pixels
Border: 0 pixels
Vertical:
Active Time: 1024 lines
Sync Offset: 1 lines
Border: 0 lines
Digital Separate, Horizontal Polarity (+) Vertical Polarity (+)
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(72-89) Detailed Timing / Descriptor Block 2:
Monitor Serial Number:
Q5L050100001
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(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
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(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
ViewSonic Corporation
Vertical Image Size: 270 mm
Normal Display - No Stereo
Blanking Time: 408 pixels
Sync Pulse Width: 112 pixels
Frequency: 63.98 KHz
Blanking Time: 42 lines
Sync Pulse Width: 3 lines
Frequency: 60.02 Hz
Confidential - Do Not Copy
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VA702-3_VA702b-3