LG U300 Service Manual page 113

4. TROUBLE SHOOTING
4.17.4 Microphone for Main MIC
Main Microphone path as below:
MIC → C527,C528 → MSM6250A → MIC feedback gain logic → MSM internal CODEC
C519 C526
10u
47p
SP0102BE3
5
G3
U502 4
PWR
3
G2
2
G1
1
OUT
C534 C535
NA NA
Start
Make a call
MIC_BIAS(C519) is 1.8V
make some sound or
voice to MIC
Can you scoping some
sound signal at C527,C528
Change the Main B'd
MICBIAS
MIC
C527 22n
MIC1N
C528 22n
MIC1P
NO
Change the Main Bíd
YES
NO
YES
NO
- 114 -
AUDIO
Near to MSM
Change the MIC
YES
Work well?
MIC2N
C201
MIC2P
10p
C202
10p
Near to MSM
END