LG GM750 Service Manual page 126

4.10.2. Headset path (Voice & Multimedia play)
Voice path for Head_Set as below:
MSM7200A HPH_R, HPH_L
CN401 u-USB connector
Connect the phone to network
Equipment and setup call
Setup 1KHz tone out
And insert head_Set
Or Play Multimedia Contents
(Or Some Sound Signal)
appear at C515, C516 ?
The sine wave appear at
Can you hear the tone
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Only for training and service purposes
C515, C516 IC501 (Audio Subsystem)
Start
And insert headset
YES
The sine wave
YES
C404, C449 ?
YES
or sound?
YES
END
C404, C449 #2, #3 pin of
NO
Change the Main board
NO
Check the IC501
Or change the Main b'd
NO
Check the CN401
or change the Main b'd
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4. TROUBLE SHOOTING
LGE Internal Use Only