Service manual

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 and USB board
6.1 MB BOARD
The MB board is a Four-layer, single-landed design with ground and internal planes provided. DC power from the
power board enters the board through a 8P connector. The other connector on the board is for the button board. The
VGA cable is a signal cable that carries the video, sync and DDC signals from the PC VGA adapter. This system
board consists of 4 functional areas: flat panel controller, MCU with flash ROM, and power regulators
USB function.
. 6.1.1 Flat panel controller… Gm1601(U21)
The heart of the system board is the Realtek Gm1601. The Gm1601 is a graphics processing IC designed for LCD
monitors. It provides all key IC functions required for LCD displays. On-chip functions include a high-speed
triple-ADC, PLL, high scaling engine and 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 14.318 MHz crystal is recommended.
b) Analog to Digital Converter:
The Gm1601 chip has three ADC's (analog-to-digital converters), one for each color (red, green and
blue) .The analog RGB signals are connected to Gm1601 as described below
Pin Name Pin Number
Red + D2
Red - D1
Green + C2
Green - C1
Blue + B2
Blue - B1
Viewsonic Corporation 31 VP2130b-1 Confidential - Do Not Copy