BenQ M2700HD, Service Manual, Page: 47 / 53

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- Signal TTL horizontal sync. (Hsync) inputs via CN102 #13, and then clamped by ZD101 Zener,
passes through FB101,R169, and then goes into IC U111 (scaler) #29.
- CN102#5 is defined as cable detect pin, this detector realize passes through R290 Pull high, go
into U111#225.
5.6.1.2 Buttons Control
- Button “Power” in right of bezel connects to U103 #3 through R412, via CN109#4.
- Button “UP” “DOWN ““MENU” “ENTER” in the bottom of bezel connects to U111 #75,#76,
through R273,R274, via CN109 #1, #2
- U113 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”, U103 #11 sends out a high potential, via R129, flow to CN108 #2
on IR board, LED Green ON.
b. When press button “power”, U103 #14 sends out a high potential, via R123, flow to CN108 #1
on IR board, LED Red ON.
c. When in “Suspend” mode, U103 #14
，
#11 sends out a high potential, via R129,R123 flows to
CN108 #1, #2 on IR board, LED Amber ON.
5.6.1.3 Mstar CHIP U111 (scaler)
- U111 (MST6378UCL) #183~#192 and #197~#206 output 8 bit LVDS digital data to panel control
circuit through CN107.
- U111 (MST6378UCL ) #230 outputs Brightness “PWM” signals to control CCFL brightness.
- U111 (MST6378UCL ) #173 output PANEL_ENABLE to make Q111 conducted, and then make
Q109 conducted, +5V flow to CN107#1~#3 as Panel VDD .
- U111 (MST6378UCL) #174 output CCFL_ON/OFF ”H” and “L” potential to control Inverter on/off.
Please refer to MST6378UCL Pin Assignments table in page
5.6.1.4 Regulator Circuit
- VCC5V is from power board supply for Panel, LED, MCU used.
- VCC3.3V generates from VCC16V through IC101 which is 3.3V for U102 and U101
used.
- DDR18V generates from VCC3.3V through U102 which is 1.8V.
- VCC1.26 generates from VCC3.3V through U101 which is 1.26V.