LG C3400 Service Manual page 79

4. Troubleshooting
Checking Flow
Resolder J200
Does the audio
profile of the phone
change to the
earphone mode?
YES
Set the audio part of the test
Equipment to echo mode
Can you hear your
the earphone?
YES
Earphone will work properly
START
NO
Change the earphone
and try again
NO
Can you hear your
voice from
voice from
the earphone?
YES
Change earphone
YES
NO
Level at pin1
of U200 is high
YES
Set the audio part of
the test equipment to
PRBS or continuous
wave mode
Can you hear
the sound from
the earphone?
YES
Download software.
Does it work well?
NO
Change the main board.
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Replace U200
Resolder component
Download software
No
Voltage at
C209 and C217
=1.2V ?
YES
Check soldering
C209, C217,
R210, R218
YES
Change the main board.