LG LG-E400 - Troubleshooting; SIM Error; No Network Connection;Losing Network

4. TROUBLE SHOOTING
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Only for training and service purposes
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4.18.3 Speaker/Speaker Phone path
MSM7225A LINE_OP, LINE_ON → C716, C718(TP3) → M700(TPA2055D3 : Audio Subsystem) → FB705, FB706(TP2) →
CN700(TP1)(Antenna + SPK pad)
Yes
No
START
END
Yes
No
Connect the phone to network
equipment and set-up call.
Set-up 1KHz tone out.
No
Yes
Re-contact or Change the SPK/RCV module
No
Change the SPK/RCV module
Change the M700 (Audio Subsystem)
Yes
Change the U200 (MSM7225A) or
Change the main PCB
Can you hear the 1KHz TONE?
The Sine wave appears at
CN700 (TP1)
The Sine wave appears at
FB705, FB706(TP2)?
The Sine wave appears at
C716, C718(TP3)?