LG F1200 Service Manual page 48

(5) Microphone Trouble
MICBIAS
MICP
MICN
• Microphone Signal Flow
- MIC is enabled by MICBIAS
- MICBIAS is supplied from ABB (SYREN)
- MICP, MICN signal to ABB (SYREN)
• Check Points
- Microphone bias level
- Audio signal level of the microphone
- Soldering of components
The Voltage Level of
C552 is about 1.8V ?
YES
Check the signal Level
after input an signal to MIC (L503, L504)
YES
ABB is out of order
Replace the Main-PCB
R542
1K
C551
10u
C515
R525 47
0.1u
C514
R526 47
0.1u
START
10u
C550 R543
2.4K
C553
47p
R544
C552 C554
1.2K
47p 47p
NO
Soldering status of
R543, R542 is OK ?
YES
ABB is out of order.
Replace the Main-PCB
NO
Soldering status of R525, R526,
C514, C515 is OK?
YES
MIC is out of order
Replace MIC500
- 47 -
4. TROUBLE SHOOTING
MIC500
1
2
OB4-15L42-C33L
NO
Resolder
R543, R542
NO
Resolder R525,
R526, C514, C515