LG LG9200 Service Manual page 51

4. TROUBLE SHOOTING
Microphone Trouble (2)
• 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.
Microphone Trouble (3)
MICP
MICN
• Trouble Shooting Procedure
- Check the bias of the microphone.
- Check the audio signal path.
- Check the soldering.
- Check the microphone.
The waveforms at MICP and MICN
- 52 -
AC voltages of the signals