LG -P990 Service Manual page 124

4.12.5 Ear-MIC troubleshooting
Ear MIC control signals are generated by WM8994(U1001), and Power is supplied by MAX8907C(U60).
Yes
END
Yes
Change the upper FPCB
LGE Internal Use Only
START
Check the main ear-jack and recomect the lower FPCB
Ear sound is OK?
No
Check the waveform of TP1.
Waveform is OK?
No
Change the codec IC or main PCB
Sound or MIC is OK?
Yes
Ear MIC is OK?
No
Check the EJ_MICBIAS(TP)
Voltage is .V?
No
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4. TROUBLE SHOOTING
Yes
END
Yes
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