Microphone Trouble - LG KC780 Service Manual

5. TROUBLE SHOOTING

5.7 Microphone trouble

Check Points
-Microphone hole
-MICBIAS & Signal comes from
-Audio signal level of the Microphone
-Soldering of components
START
Check microphone sound
hole
Yes
MIC bias TP2
(2.5V)when
call?(L600)
Check the signal
TP1 level at each
side of MIC600.
Check the
connection of
F-KEY FPCB
Replace Main PCB
LGE Internal Use Only
VMIC
TP1
L601 100nH
MIC_P
C602
DNI
L602 100nH
C600 27p
MIC_N
C603
C606 C604
27p 27p 27p
ON
No
Yes
No
Yes
No
Yes
TP2
MIC MIC
C601
MIC600
1
0.1u O
2
G1
C615
3
G2
4
0.1u P
SPM0204HE5-PB-3
C605
2.2u
Check MIC. Bias line
Replace
microphone
(MIC600)
Connect the F-KEY
FPCB or replace it.
- 84 - Copyright © 2008 LG Electronics. Inc. All right reserved.
MIC Bias
(L101)
TP2
MIC Signal
(C603, C604)
TP1
Only for training and service purposes