LG KP105 Service Manual page 75

4. TROUBLE SHOOTING
CHECKING FLOW
START
Does the audio
profile of the phone
change to the
earphone mode?
Mic
Check voltage level
of TP2
Check component status
around Vmic
Check the signal Level
at HS_MIC.
Is it about 1.2~1.5V DC
with a few tens mV AC?
Replace U103 or
Change another Ear-Mic set and Try again
LGE Internal Use Only
No
Check the voltage Level
TP1(CN301.8) = Low?
Yes
No
Check U103
No
Re-solder or
replace the Component
No
Re-solder causal
component
(CN301)
Yes
No
Re-solder CN301 or Change
another Ear- Mic set and Try again
Yes
Replace U103 or Change Board
Earphone
Acoustic
Does waveform at
TP3 (U103.HS_REC)
fluctuate?
Does waveform at
TP4 and TP5 fluctuate?
Yes
Does waveform at
TP6 and TP7 (CN301.4,5)
fluctuate?
Change another Ear-Mic set and Try again
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No
Replace U103 or
Change the board
No
Check U201 and
component status
around U201
Re-solder causal
No
component
(CN301,C308,.etc.)
Only for training and service purposes