Interface Board And Panel Power Supply; Video Input Circuit; System Reset, Led Control Circuit; E 2 Prom For Edid - NEC MultiSync 20WGX2 Series Service Manual

1. Interface Board and Panel Power Supply

1.1 P303 connector
A 5V power supply for LCD module, scaler, and logic is generated from the P303 connector.
A12V power supply for LCD module.
1.2 I307 , I306, I317 terminal regulator
I307 : A 3.3V power supply for Scaler IC I308 and SDRAM IC I311/I312 are generated from the 5V.
I306 : A 1.8V power supply for Video IC I901 and AScaler IC I308 are generated from the 3.3V.
I317 : A 3.3V power supply for USB IC I319 is generated from the 5V.
I313 ON/OFF control for LCD Module
I327 ON/OFF control for USB hub circuit.

2. Video Input Circuit

The analog video signal input enters from P306 and P311, the AC-coupled video signal is used to clamp
the black level at 0V.
The digital TMDS input enters from P302.

3. System Reset, LED Control Circuit

3.1 System Reset
System reset is performed by detecting the rising and falling of the 5V source voltage at I308.
3.2 LED Control Circuit
Blue / amber control signal of the LED BLUE and LED AMBER signal pin 204, 203 from I308.
4. E PROM for EDID
2
The EDID of Analog input is stored in I303 and the EDID of Digital input is stored in I304 for DVI CE and
I334 for DVI PC to access the information of monitor.
5. E PROM
2
Data transfer between I310 (24LC32B) and scaler IC I308 is effected through the IIC bus SCL (pin 98) and
SDA (pin 99) of I308. The data to be transferred to each device are stored in I310.
I309 control data.
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OSD related setting data.
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Other control data for service menu.
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