Acer AL1917W C Manuale di servizio - Pagina 8

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- Signal TTL horizontal sync. (Hsync) inputs via CN103 #13, and then clamped byZD106 Zener,

passes through FB101,R130, and then goes into IC U105 (scaler) #27.

- CN103#5 is defined as cable detect pin, this detector realize passes through R122 Pull hight, go

into U105#35.

- U103 power is supplied by PC via CN103#9, or supplied by Monitor self via D103.

- U103 is an EEPROM IC which is memory and EDID data saved in it.

3.2.2 Buttons Control

- Button "Power" on right side bezel connects to U105 (scaler) #88 through R161, via CN105#4.

- Button "UP" "DOWN ""MENU" "AUTO" on right side bezel connects to U105 (scaler)

#89,#88,#89,#88 through R158,R159,R160,R157,via CN105 #6, #5.

- U108 is an EEPROM IC which memory OSD setting and save the value adjusted by user.

- LED Indicator on Front Bezel

a. When press button "power", U105 (scaler) #42 sends out a low potential, via R101, flow to

CN105 #2 on keypad, LED Green ON.

b. When in "Suspend" mode, U105 (TSUM56AL) #41 sends out a low potential, via R107, flows

to CN105 #1 on keypad, LED Amber ON.

3.2.3 Mstar CHIP U105 (scaler)

- U105 (TSUM56AL-1& TSUM16AL-1) #54. #55. #58~#65 output 8 bit even LVDS digital data

to panel control circuit through CN104.

- U105 (TSUM56AL) #67~#74. #77. #78 output 8 bit odd LVDS digital data to panel control

circuit through CN104.

- U105 (TSUM56AL-1& TSUM16AL-1) #86 outputs Brightness "PWM" signals to control CCFL

brightness.

- U105 (TSUM56AL-1& TSUM16AL-1) #48 output PPWR "H" potential to make Q103

conducted, and then make Q101 conducted, +5V flow to CN104#1~#3 as Panel VDD .

- U105 (TSUM56AL-1& TSUM16AL-1) #85 output CCFL_ON/OFF "H" potential to control

Inverter on/off.

- TCLK by Crystal 14.318MHz input to U105 (TSUM56AL-1& TSUM16AL-1) #96,#97.

Please refer to TSUM56AL Pin Assignments table in page

3.2.4 Regulator Circuit

- +5V is from switching mode power supply for Panel used.

- +3.3V generates from +5V through C101 and C103 filtering and U101 which is output +3.3V

LDO for U103, U106,U108 and U105 used.

- +1.8V generates from +5V through C101 and C103 filtering and U102 which is output +1.8V

LDO, for U105 used.

3.2.5 Audio circuit

- Audio Signal R,L,GND input through P701,#2,#5,#1, Stop DC via C711, C712, and then enter

into U701 (TDA7496L) analog input terminal #4,#9.

- U701 (TDA7496L) #14,#17 output R,L audio data to Speaker through CN701.

- U105 (TSUM56AL) #94 output MUTE "H" potential to control U701on/off.

- U105 (TSUM56AL) #93 outputs Volume "PWM" signals to control U701 Volume.

4. Inverter circuit

1. R503, ZD501, R502, Q501 components convert +14V voltage into +5.0V voltage, and the voltage

supply to IC501. The extra PWM pulse signal (BRIGHTNESS signal) input to control IC through R512,

R514, C510, The LCT pin is set to a DC voltage of 0.7V by using a resistor divider(R507, R516), change the

duty of PWM pulse, will regulate the lamp current. The ON/OFF voltage connect to pin10 of IC501 through

D501, R501, A voltage of 2V to pin10 of IC501 enables the IC and activates the striking timer. The

SSTCMP pin of IC501 performs the soft function, the C511 set the time of SST. The operation frequency

determined by external capacitor C512, C521 and resistor R508 connected at CT pin of IC501. C515 connect

the TIMER pin of IC501, the capacitor to set striking time and shunt down delay time. DRV!, DRV2 output

Service Manual