LG KU250 Service Manual - Page 110
Speaker phone path
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4. TROUBLE SHOOTING 4.18 Speaker phone path MSM6245 LINE_P,LINE_N → R429/R427, C423/C422, R431/R426 → Audio AMP(U402) → Analog Switch(U401) → Speaker Start Connect the phone to network equipment and setup call Setup 1KHz tone out Can you hear the tone? NO Sine wave appears at R429/R427 and C423/C422 And R431/R426 ? YES SPK_AMP_EN is2.6V? YES The sine wave appears at SPK+, SPK- ? YES The sine wave appears at SPK_RCV-,SPK_RCV+? NO Change the Main board YES END NO Change the Main board NO Change the Main board NO Change the Audio Amp YES Change speaker - 111 -
4. TROUBLE SHOOTING
- 111 -
4.18 Speaker phone path
MSM6245 LINE_P,LINE_N
→
R429/R427, C423/C422, R431/R426
→
Audio AMP(U402)
→
Analog
Switch(U401)
→
Speaker
Start
Connect the phone to network
equipment and setup call
Setup 1KHz tone out
Sine wave appears at
R429/R427 and C423/C422
Change the Main board
NO
SPK_AMP_EN is2.6V?
Change the Main board
NO
YES
The sine wave appears at
SPK_RCV-,SPK_RCV+?
YES
NO
Change speaker
YES
Change the Main board
The sine wave appears at
SPK+, SPK- ?
Change the Audio Amp
NO
YES
And R431/R426 ?
Can you hear the tone?
YES
NO
END