LG KU800 Service Manual page 123

4. TROUBLE SHOOTING
4.19.5 Microphone for Head_Set
MIC for Head_Set path as below:
Insert Headset → EAR_SENSE_N(pin8) go 0V → MSM6275 sense Head_Set insertion →
MIC signal go to MSM( to C215)
CN503
21
19
1
2
3
R508
4
R509
5
0
6
0
7
8
9
10
11
12
13
14
15
16
17
18
20
22
C505 33u
C506 33u
C507
1 2
IN OUT
3 4
G1 G2
NFM21PC105B1A3
Start
Make a call
Try change the head set
NO
EAR_SENSE_N is 0V?
Yes
MIC_BIAS is 1.8V ?
Yes
Change the Main B'd
MIC2N
EAR_MIC2P
HPL_L
HPL_R
EAR_SENSE_N
+VPWR
REMOTE_PWR_ON
+5V_PWR
U
USB_VBUS_IN
UART_TX
UART_RX_IN
OK
END
NO
Change headset or
main board.
NO
Change the Main B'd
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SDCC_DAT1
SDCC_DAT2_
SDCC_DAT3_
MDP_VSYNC_SECONDA_