LG U990 Service Manual page 128

4.12.3 Loud speaker path (voice speaker phone/VT)
Loud speaker path as below:
MSM6280 SPK_R, SPK_L → C532,C541 → R510,R516 → C533,C542 → R511,R517 →
U502(audio codec) → FB500,FB501 → CN603(B'toB connector) → OUT800, OUT801 (SPK PAD) →
Speaker
Connect the phone to network
Equipment and setup call
Setup 1KHz tone out
Set phone with speaker phone mode
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Only for training and service purposes
Start
The sine wave appear at
C532,C541?
YES
The sine wave appear at
FB500, FB501?
YES
The sine wave appear at
pads of speaker?
YES
Can you hear the tone?
YES
END
4. TROUBLE SHOOTING
NO
Change the Main board
NO
Check the U502 or
Change the Main board
NO
Check the CN603
NO
Change the speaker
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