Service manual

4-6. THEORY OF OPERATION
This section describes the function of the LCD monitor per functional block.
This monitor includes MB board, inverter board, adapter and button board.
MB Board
The MB board is a four-layer, single-landed design with ground and internal planes provided. DC power from the
power adapter enter the board through DC jack. Other connectors on the board are for inverter, audio and 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, flash ROM , power regulator and
Audio amplifier
Flat panel controller… MST8116A (U3)
The heart of the system board is mstar MST8116A. The MST8116A 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 and on-chip micro controller.
a) Clock Generation :
Crystal Input Clock (TCLK and XTAL). This is the input pair to an internal crystal oscillator and
corresponding logic. A 14.318 MHz crystal is recommended.
b) Analog to Digital Converter:
The MST8116A chip has three ADC's (analog-to-digital converters), one for each color (red, green and
blue) .The analog RGB signals are connected to
MST8116A as described
below
Pin Name Pin Number
Red + 63
Red - 62
Green + 60
Green - 59
Blue + 58
Blue - 57
c) OSD : The MST8116A has a fully programmable ,high-quality OSD controller. The on-chip static
RAM(4096 words by 24 bits) stores the cell map and the cell definitions.
d) MTV312 Micro controller: The MTV312 micro controller(MCU) serves as the system micro controller. It
programs the MST8116A and manages other devices in the system such as the keypad, the backlight, LED,
audio and non-volatile RAM. using general purpose input/output (GPIO) pins.
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