ViewSonic VX910 Service Manual page 22

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 board enters the board through
6P connector (CN6)...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 3 functional areas: flat panel controller, flash ROM,
power regulator.
6.1.1 Flat panel controller... MST8131A (U3)
The heart of the system board is the scalar chip of MST8131A. The MST8131A 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.
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 (U5). It is active high.
c) Analog to Digital Converter:
The MST8131A 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 MST8131A as described below:
d) OSD: The MST8131A has a fully programmable, high-quality OSD controller. The on-chip static
RAM stores the cell map and the cell definitions.
ViewSonic Corporation
Pin Name
Red +
Red -
Green +
Green -
Blue +
Blue -
H sync
V sync
Pin Number
63
62
60
59
58
57
37
38
19
Confidential - Do Not Copy
VX910