U8185
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-03-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
46
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No W900/850
transmission
Upgrade the
software. Problem
solved?
End
Is the antenna in
good contact?
Re-install the
antenna
Is U3402 soldered
properly?
Re-solder or replace it
Are C3411, L3403,
C3403, and C3404
soldered properly?
Re-solder or replace
them
Are U3401's power
supply and control
signal normal?
Re-solder or replace
the U3401, replace
C3430 or C3431 on the
power supply network,
or replace C3306,
C3307, or R3405 on the
control circuit
Is U3404 soldered
properly?
Re-solder or replace it
Are L3401, C3419,
and C3418 soldered
properly?
Re-solder or replace
them
Send the phone to an
advanced service site
for repair
Failure: No reception; the phone cannot initiate or receive a call, or access the network.
Solution: