LG -d821 Service Manual page 142

3.8.4 SUB MIC troubleshooting
A sub MIC is located on Main PCB.
It operates in case of voice call (Speaker phone).
LGE Internal Use Only
START
Check the MIC signal by
Speaker Loop back test
Is Speaker sound OK?
No
Check the MIC hole to make clear the
voice signal path
Is voice signal ok?
No
Check the MIC mesh filter, rubber.
Is voice signal ok?
No
Check the sub MIC.
Is voice signal ok?
No
Change the WCD9320(U10000)
Is receiver Sound OK?
No
Change The main PCB
Yes
Yes
Yes
Yes
Yes
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3. TROUBLE SHOOTING
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Only for training and service purposes