Audio Troble - LG E475F Service Manual

3.18 Audio Troble

3.18.1 Receiver Path
MSM7225A-0-AB EAR1_OP, EAR1_ON -> RCV_P, RCV_N -> R4023, R4021 (TP3) ->U4001 (PM8029 : PMIC) ->FB4001,
FB4000 (TP2) -> CN7000 (TP1) (SPK Pad)
Connect the phone to network
equipment and set-up call.
Can you hear the 1KHz TONE?
Change the U2000 (MSM7225A) or
LGE Internal Use Only
START
Set-up 1KHz tone out.
No
The sine wave appears at
CN7000 (TP1) ?
No
The sine wave appears at
FB4001, FB4000 (TP2)?
No
The sine wave appears at
R4023, R4021(TP3)?
No
Change the main PCB
Yes
END
Yes
Re-contact or Change the SPK/RCV
module
Yes
Change the SPK/RCV module
Yes
Change the U4001 (PMIC)
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3. TROUBLE SHOOTING
Only for training and service purposes