Huawei U8185 Maintenance Manual page 74

U8185
Maintenance Manual
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When the WCN2243 is operating, it sends the frequency that is expected to be received
through the I
mixes the signals in the specified frequencies (76–108 MHz) into the intermediate frequency.
The signals then go through the intermediate frequency filter, demodulation module, decoding
module, and are converted to audio output.
The FM radio uses a headset as the antenna. Therefore, a headset must be inserted for the FM
radio to function.
Troubleshooting Process
Failure: The FM radio is malfunctioning.
Solution: If signals can be received but not sound is heard, check the headset line.
Issue 1.0 (2012-03-23)
Frequency modulation
Frequency reception and mixing
Frequency demodulation
MPX decoder
2
I C interface
2
C interface to the frequency selection module. The frequency mixing circuit
−
No FM signal
− No sound for FM radio
FM radio tuning result is
not satisfactory
Replace the headset.
Problem solved?
N N
Check and re-solder the
headset jack. Problem
solved?
N N
Does signal exist on I2C?
N N
Is U6000 soldered
properly?
Y Y
Send the phone to an
advanced service site
for repair
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Copyright © Huawei Technologies Co., Ltd.
End
Y Y
End
Y Y
N N Re-solder or replace it
9 Principles and Failure Analysis
69