LG U8290 Service Manual page 141

4. TROUBLE SHOOTING
Microphone for Head_Set
MIC for Head_Set path as below:
Insert Headset → Ear_Sense(R624) go 0V → MSM6250 sense Head_Set insertion → MIC signal go
to MSM(C102, C115)
HEADPHONE_L
HEADPHONE_R
Try change the head set
EAR JACK
MICBIAS_LDO_1.8V
10K R625
VREG_MSMP_2.6V
22n C102
MIC2P
C115
22n
MIC2N
33u C626
33u C627
0 R624
EAR_SENSE*
MULTI_ADC
KEY_ROW(0)
KEY_ROW(1)
KEY_ROW(2)
KEY_ROW(3)
KEY_COL(6)
VA8
C654 C653
39p 39p
AVLC14S02050
Start
Make a call
NO
Ear_sen se(R624) is 0V?
Yes
EXT_MIC is b iased
about 2 .0V?
Yes
Change the Main B'd
To prevent from
TDMA noise.
R640 600
R641 600
D503
OK
END
NO
Check R624 o r ch ange
the Main B'd
NO
Check Head P hone
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