Button Control - ViewSonic VX1935wm-3 Service Manual

noise. Signal HSYNC and VSYNC input through CN103 #13 and #14, and C125, R137, C126, R136 filtering.
Then the analog signal enters U105, and then U104 deals with it internally. In addition, TVS101, TVS102,
TVS103, TVS104 (the four are BAV99), ZD101, ZD105, ZD106, ZD107, ZD108(they are constant voltage
diode of 5V6) are ESD protector. Signal DDC-SCL inputs via CN103 #15, and then passes through ZD101 for
ESD protection, goes into EDID EEPROM IC U103. Signal DDC-SDA inputs via CN103 #12, and then passes
through ZD107 for ESD protection, goes into EDID EEPROM IC U103. CN103 #5 is defined as cable detect
pin, this detector realizes via R124 and U105 # 35,The PC-5V of U103 is supplied by PC via CN103 #9 with
D103 for ESD protection, or supplied by Monitor self via D103.U103 is an EEPROM IC, which is a kind of
memory and used for saving EDID data.

4.2.4 Button Control

Button "Key-Power" is defined as power on/off, which is connected to U105 # 90 through CN105 # 6.
Button "Key-2" is defined as two functions of selecting and adjustment, which is connected to U105 #94
through CN105 # 5.
Button "Key-Up" is defined as plus, which is connected to U105 # 95 through CN105 # 8.
Button "Key-Down" is defined as minus, which is connected to U105 # 99 through CN105 # 7.
Button "Key-1" is defined as two functions of menu and exit, which is connected to U105 # 89 through
CN105 # 4.
LED indicator on the front bezel is defined as follows:
a. When press button "Key-Power", U105 # 91 is pulled down and U105 # 92 is pulled high, so Q102 is
conducted and the LED indicator is green.
b. When in power-saving mode, U105 # 91 is pulled high and U105 # 92 is pulled down, so Q105 is conducted
and the LED indicator is orange.
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