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CHECKING FLOW
START
Does the audio
profile of the phone
change to the
earphone mode?
Yes
Key
Go to Key
Trouble section
Check the Level of
CN400.8~12 change,
when you press any keys
Yes
Sound
Go to Speaker Trouble
Check the Level of
U402.C2 = High ?
Yes
Check the Signal, U404.A2
and U404.C2
Yes
Does waveform at
CN4100.4 and CN400.5
fluctuate?
Yes
No
Check the voltage Level
CN400.7 = Low?
Yes
Replace U100 or
Change Board
No
Resolder CN400
Change another Ear-Mic set and Try again
No
Replace
R427
No
Replace
U402
Resolder causal
component
(CN400, R408 etc.)
Change another Ear-Mic set and Try again
Figure 4-86.
- 123 -
4. TROUBLE SHOOTING
No
Re-solder CN400 or Change
another Ear-Mic set and Try again
Mic
Go to MIC
Trouble section
Check the signal
Resolder causal
No
Level at AUX_MIC_P.
component
Is it about 1.2~1.5V DC
with a few tens mV AC?
(CN400, R408 etc.)
Yes
Acoustic
Does waveform at
No
U100.J16 and U100.K16
fluctuate?
Yes
Does waveform at
No
CN400.4 and CN400.5
fluctuate?
Yes
No
Check the Level of
U402.C2 = Low ?
Yes
Earphone
Replace U100 or
Change the board
Resolder causal
component
(CN400, R408 etc.)
Replace R427
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