LG U400 Service Manual page 118

4. TROUBLE SHOOTING
START
Check the MIC bias level
at the pad of MIC
2
No
Check the signal level
Is the level of MIC+ AND MIC-
at C601 at the putting
1
2.4Volt ?
Audio signal in MIC
Yes
Yes
3
Resolder C601,C602, R600
No
A few hundred of mV
and try again.
of the signal measured ?
If fail again,
chage the main Bíd
Change the MIC
Yes
Change the main B,d
Ye s
No
Does it work properly ?
YES
END
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