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U8815
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-02-13)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
56
Figure 9-43
Troubleshooting process for sound failure
Is the call normal after the
software is reloaded?
Is the call normal
after the MIC is re-soldered?
Is the MICBIAS voltage normal?
Check C507.
Return the handset to the
factory for repair.
N
N
N
Y
Y
N
End
Is the call normal
after the MIC is replaced?
Y
Y
End
End
After a call is
established, no sound is
heard by the other party.
Table 9-11 describes signals in the circuit diagram in this section.
Table 9-11
Description of the signals in the circuit diagram in this section
Signal
Description
Reference
Measurement or
Wave Form
MIC1_P
Input from the primary microphone.
None
MIC1_N
Input from the primary microphone.
None
AUXI_P
Input from the secondary microphone.
None
AUXI_N
Input from the secondary microphone.
None
MSM_MICBIAS
Bias voltage of the primary microphone
None