U8655
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-02-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
51
Troubleshooting the Failure that No Sound Can Be Heard by the Other Party
During a Call
No sound can be heard by
the other party during a call
Replace the
microphone. Is the
problem solved?
End
Is the MIC_BIAS voltage
equal to 1.8 V?
Return the phone
to the f actory
Check U201
N
N
Y
Reinstall the phone's
f irmware. Is the
problem solved?
End
Y
Y
N
9.4.13 Touchscreen Panel
The U8655N's 3.5-inch capacitive touchscreen panel has a touch key area containing three
touch keys. The backlight LEDs for the three touch keys are located on the PCBA. A light
guide film is used to guide light from the LEDs to the touch key area.
The following table describes the interfaces between the touchscreen panel, MSM7225A and
PM8029.