LG KF750 Service Manual page 109

4. TROUBLE SHOOTING
1
2
3
4
LGE Internal Use Only
START
Connect the phone to network
Equipment and setup call
Setup 1KHz tone out
Does the sine wave appear
at R518, R519 ?
YES
Does the sine wave appear
at Number 65, 66 pin
in the main Bíd CN702?
YES
Does the sine wave appear
at EAR(+) PAD in LCD FPCB?
YES
Does the Receiver get in
contact with the LCD
FPCB sus
YES
Can you hear sine wave
out of the receiver ?
YES
END
NO
Change the main board
The sine wave not appear
NO
Check 5, 8 pin at U501
NO
Change the LCD FPCB
NO
Re-assemble the Receiver
NO
Change the Receiver
Copyright © 2008 LG Electronics. Inc. All right reserved.
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Only for training and service purposes