LG MG200 Service Manual page 61

4. TROUBLE SHOOTING
Microphone Signal Flow
• MIC is enable by MICBIAS
• MICBIAS, MICP, MICN signals to ABB
Trouble Shooting Setup
• Initialize GSM MS test equipment.
• Connect PIF-UNION to the phone, and power on.
• Make a test call to 112.
• Make a sound in front of the microphone
Trouble Shooting Procedure
• Check the bias of the microphone.
• Check the audio signal path.
• Check the soldering.
• Check the microphone.
• Check the operation of FPCB
Check Points
• Microphone bias
• Audio signal level of the microphone
• Soldering of components
MICP
MICN
The waveforms at MICP and MICN
AC voltages
of the signals
- 60 -
MICN MICP MIC Bias
R202
MIC Bias
C202