U8655
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-02-23)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
31
GSM/DCS transmission
f ailure
When the RF cable is not
inserted, are U3201's pin
1 and pin 2 connected?
Check U3201
Are U3202's control signals
normal?
Check U401
Are U3501's GSM output
and DCS output
approximately 33 dBm and
30 dBm respectively?
Check U3202 and
U401
Check U3501
Y
N
Y
Y
Y
N
N
Do U3801's pin A10 and pin
A9 have output?
Check U3801
N
Y
NOTE
The following tables describe the working status of the GSM/DCS power amplifier U3501.
GSM_PA_EN
PA
H
ON
L
OFF
GSM_PA_BAND
MODE
L
GSM850/900
H
DCS1800/1900
H: voltage higher than 1.3 V. L: voltage lower than 0.5 V.
WCDMA transmission failure (use W2100 as an example)
Before starting the following process, make sure that the USIM card and the antenna are well
connected.