![background image](http://html1.mh-extra.com/html/viewsonic/va721-2/va721-2_service-manual_1020970025.webp)
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 enters the board through a 6P 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.
6.1.1 Flat panel controller: MST8111A(U3)
The heart of the system board is the Realtek MST8111A. The MST8111A 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 MST8111A chip has three ADCs (analog-to-digital converters), one for each color (red, green and blue).
The analog RGB signals are connected to MST8111A as described below.
Pin Name
Pin Number
Red +
63
Red -
62
Green +
60
Green -
59
Blue +
58
Blue -
57
c)
OSD: The MST8111A 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.
ViewSonic Corporation
Confidential - Do Not Copy
VA721-2
22
Содержание VA721-2
Страница 34: ...Pattern 5 Pattern6 Pattern 7 Pattern 8 Pattern 9 ViewSonic Corporation Confidential Do Not Copy VA721 2 31...
Страница 36: ...7 Appendix A How to install the software for ISP ViewSonic Corporation Confidential Do Not Copy VA721 2 33...
Страница 51: ...1 No Power 6 Troubleshooting Flow Chart ViewSonic Corporation Confidential Do Not Copy VA721 2 48...
Страница 52: ...2 No Characters Missing Color 3 Always show NO SIGNEL ViewSonic Corporation Confidential Do Not Copy VA721 2 49...
Страница 59: ...8 Exploded Diagram And Spare Parts List ViewSonic Corporation Confidential Do Not Copy VA721 2 56...
Страница 65: ...12V MC34063 MC34063 AIC1739 2 Power 12V 5V 2 5V 3 3V ViewSonic Corporation Confidential Do Not Copy VA721 2 62...
Страница 72: ...11 PCB Layout Diagrams Main board Control board ViewSonic Corporation Confidential Do Not Copy VA721 2 69...