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 enter the board through a 6P connector. Other connector on the board is for 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, MCU with flash ROM , power regulator .
6.1.1 Flat panel controller… RTD2523(U7)
The heart of the system board is RealTek RTD2523. The RTD2523 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.
a)
Clock Generation :
Crystal Input Clock (TCLK and XTAL). This is the input pair to an internal crystal oscillator and
corresponding logic. A 24.576 MHz crystal is recommended.
b)
Analog to Digital Converter:
The RTD2523 chip has three ADC's (analog-to-digital converters), one for each color (red, green and
blue) .The analog RGB signals are connected to RTD2523 as described
below
Pin Name
Pin Number
Red +
37
Red -
38
Green +
34
Green -
35
Blue +
30
Blue -
31
c)
OSD : The RTD2523 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’s
programs the RTD2523 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.
Pin number
Pin Name
Pin Number Usage
1
P5.2
Key / Power on ,off
13
P3.4
NV_RAM (U4) SDA
14
P3.5
NV_RAM (U4) SCL
41 P5.4
Key_down
40 P5.5
Key_right
42 P5.3
Key_up
34 P5.6
Key_left
9 P6.3
Key_mute
2 P5.1
Key_select
27 P6.0
LED_red
26 P6.1
LED_green
16
P6.2
LCD panel power1 on / off control
17
P1.0
Backlight on / off control
24
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Содержание VX912
Страница 38: ...Pattern 5 Pattern6 Pattern 7 Pattern 8 Pattern 9 35 ViewSonic Corporation Confidential Do Not Copy VX912 ...
Страница 51: ...1 Display color abnormal 6 Trouble Shooting Flow Chart 48 ViewSonic Corporation Confidential Do Not Copy VX912 ...
Страница 52: ...2 Monitor can not power on 49 ViewSonic Corporation Confidential Do Not Copy VX912 ...
Страница 53: ...3 Monitor white screen 50 ViewSonic Corporation Confidential Do Not Copy VX912 ...
Страница 54: ...4 Monitor black screen 51 ViewSonic Corporation Confidential Do Not Copy VX912 ...
Страница 55: ...5 Analog input always shows NO SIGNAL 52 ViewSonic Corporation Confidential Do Not Copy VX912 ...
Страница 56: ...6 Digital input always shows NO SIGNAL 53 ViewSonic Corporation Confidential Do Not Copy VX912 ...
Страница 60: ...57 ViewSonic Corporation Confidential Do Not Copy VX912 8 Exploded Diagram And Spare Parts List ...
Страница 78: ...11 PCB Layout Diagrams 75 ViewSonic Corporation Confidential Do Not Copy VX912 Main Board Control Board ...