LG KG271 - Page 75

4. TROUBLE SHOOTING
- 76 -
CHECKING FLOW
START
Does the audio
profile of the phone
change to the
earphone mode?
Check the voltage Level
CN301.8 = Low?
Replace U100 or Change Board
Re-solder CN301 or Change
another Ear- Mic set and Try again
Mic
Earphone
Go to MIC
Trouble section
Re-solder causal
component
(CN301)
Check the signal Level
at AUX_MIC.
Is it about 1.2~1.5V DC
with a few tens mV AC?
Change another Ear-Mic set and Try again
Acoustic
Does waveform at
U102.EPPA1
fluctuate?
Replace U100 or
Change the board
Does waveform at
CN301.4 and CN301.5
fluctuate?
Re-solder causal
component
(CN302,C322 etc.)
Change another Ear-Mic set and Try again
Yes
Yes
Yes
Yes
No
No
No
No
No