Acer AL1702 AL1702 Service Guide - Page 7

AL1702 3. Interface Operation 3.1 Top (Circuit diagrams MAIN PWB 2 of 8) This page is function block. (1) power. (2) VGA & DDC interface. (3) scaler MST8111B. (4) panel interface. (5) audio (option). 3.2 Power (Circuit diagrams MAIN PWB 3 of 8) 3.2.1 P301 connector A 5V power supply for LCD module, MCU, logic. And a 12V power supply for audio function. It is generated from the P301 connector. 3.2.2 I301 : 3-terminal regulator A 2.5V power supply for scaler IC I305, it is generated from the 5V source. 3.2.3 I302 : 3-terminal regulator A 3.3V power supply for scaler I305, it is generated from the 5V source. 3.2.4 Q303, I312 : ON/OFF control for LCD module power ON/OFF control (PANELVCC_EN) is performed for power ON/OFF and also for the power saving sequence. 3.2.5 R306 : ON/OFF control for LCD module back light power ON/OFF control (BKLT_EN) is performed for black light power ON/OFF and also for the power saving sequence. 3.2.6 Q301,Q302 : Adjust back light luminance for LCD module It is adjusted back light luminance control (BKLT_ADJ) is performed for the back light luminance. 3.3 VGA & DDC interface (Circuit diagrams MAIN PWB 4 of 8) The analog video signals input, the AC-coupled video signal video signal is used to clamp the black level at 0V. and H/V sync to sclaer, and DDC plug & play function. 3.3.1 P302 connector The video input signals from the P302 connector. 3.3.2 I304DDCEEPROM This IC is support DDC2B of the VESA standard, also plug and play for the PC host. 3.4 Scaler MST8111B (Circuit diagrams MAIN PWB 5 of 8) The I305 is scaled converter LSI for the LCD monitor. The analog R, G, B signal input entered from the video input circuit is converted into the digital data of video signal through the incorporated A/D converter. Based on this conversion, this device performs interpolation during pixel extension. These interpolation digital data are transformed to LVDS signal. The I305 source voltage is 3.3V and 2.5V, the device clock frequency is 14.318 MHz. The device control signal is from MCU through the 3-wire bus. The I305 scaler has support OSD function. 3.5 Panel interface (Circuit diagrams MAIN PWB 6 of 8) 3.5.1 P305 connector The P305 is LVDS bus, output to LCD module. The output voltage is 5 voltage. 3.5.2 MCU (Circuit diagrams MAIN PWB 7 of 8) The I307 MCU is system processor. It can programmed scaler, control power save sequence for the system, input keypad function, output LED, control audio function, and ISP / DDC2Bi function. Page 5