LG U310 Service Manual page 113

4. TROUBLE SHOOTING
4.17.4 Microphone for Main MIC
Main Microphone path as below:
MIC -> C504,C506 -> MSM6250A -> MIC feed back gain logic -> MSM internal CODEC
MIC
C500
10u
SP0102BE3
5
G3
U500 4
PWR
3
G2
2
G1
1
OUT
Start
Make a call
MIC_BIAS(C505) is 1.8V
make some sound or
voice to MIC
Can you scoping some
sound signal at C504,C506
Change the Main B'd
MICBIAS
C502
47p
C504 22n
MIC1N
C507
NA
C506 22n
MIC1P
NO
YES
NO
YES
NO
Change the Main B'd
Change the MIC
Work well?
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AUDIO
Near to MSM
YES
END