U8185
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-03-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
38
No GSM
transmission
Y
Y
Y
Y
Y
Y
Y
Y
N
N
Y
Y
N
N
N
N
N
N
N
N
Y
Y
N
N
Y
Y
N
N
Y
Y
N
N
Upgrade the
software. Problem
solved?
End
Is the antenna in
good contact?
Re-install the
antenna
Are C3906 and
C3909 soldered
properly?
Re-solder or replace
them
Are R3502 to R3507
soldered properly?
Re-solder or replace
them
Are L3500, L3504,
and C3510 soldered
properly?
Re-solder or replace
them
Are L3501, C3514,
and C3513 soldered
properly?
Re-solder or replace
them
Is U3501 soldered
properly?
Re-solder or replace it
Are U3501's power
supply and control
voltage normal?
Re-solder or replace
the U3501, replace
C3521, C3503, C3522,
C3501, or C3502 on the
power supply network,
or replace C3518 or
C3519 on the control
circuit
Send the phone to an
advanced service site
for repair