6. THEORY OF OPERATION
This section describes the function of the LCD monitor per functional block.
This monitor includes MB board, inverter board, adapter and two button boards.
6.1 MB BOARD
The MB board is a two-layer, single-landed. 12V DC power from the power adapter enters the board through
DC jack. Other connectors on the board are for inverter, audio and button boards .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, flash ROM, power regulator and Audio amplifier
6.1.1 Flat panel controller… MST1831A (U3)
The heart of the system board is the scalar chip of MST1831A. The MST1831A is a high performance, dual
input graphics processing IC for LCD monitors with resolutions up to SXGA. It provides all key IC functions
required for LCD panel. On-chip functions include an 8-bit triple ADC, PLL, DVI receiver, high scaling engine,
OSD controller and dual LVDS transmitter.
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a)
Clock Generation:
Crystal Input Clock (XIN and XOUT): This is the input pair to an internal crystal oscillator and corresponding
logic. A 14.318 MHz crystal is recommended.
b)
Hardware Reset (Pin 32):
Hardware Reset signal is provided by MCU (U6). It is active high.
c)
Analog to Digital Converter:
The MST1831A chip has three ADC's (analog-to-digital converters), one for each color (red, green and
blue) .The analog RGB and synchronous signals are connected to MST1831A as described below:
Pin Name
Pin Number
Red +
63
Red -
62
Green +
60
Green -
59
Blue +
58
Blue -
57
H sync
37
V sync
38
Summary of Contents for VX750 VLCDS27089-1W
Page 39: ...2 3 3 Read DDC data from Monitor 36 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 42: ...2 Display color abnormal 39 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 43: ...3 Monitor can not power on 40 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 44: ...4 Monitor white screen 41 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 45: ...5 Monitor black screen 42 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 46: ...6 Audio noise 43 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 47: ...7 Analog input always shows NO SIGNAL 44 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 48: ...8 Digital input always shows NO SIGNAL 45 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 67: ...11 PCB Layout Diagrams Main Board 64 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 68: ...65 ViewSonic Corporation Confidential Do Not Copy VX750 Main Board...
Page 69: ...66 ViewSonic Corporation Confidential Do Not Copy VX750 Main Board...
Page 70: ...Main Board 67 ViewSonic Corporation Confidential Do Not Copy VX750...
Page 71: ...68 ViewSonic Corporation Confidential Do Not Copy VX750 Main Board...
Page 72: ...69 ViewSonic Corporation Confidential Do Not Copy VX750 Control Board...