U8815
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-02-13)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
43
Figure 9-28
Troubleshooting process for transmission failure
Are pins 1 and 2 of U3201 connected?
Check
whether the control
signal of the U3202 switch is
normal (For the truth table for control
signals, see
table 1.)
Is the W2100PA
output of U3302 normal?
Check U3402.
Check U3201 when the
handset is not connected
to the RF cable.
Check U401.
Y
Y
Y
N
N
N
Check U3202 and U401.
Check
whether the IQ signal of U3901
and the power supply voltage
are normal.
Y
N
Check U3201.
Check U3901.
Failure of the W2100
transmission channel
End
In W900, just replace the U3302 detection with U3401 detection.
In GSM900 or GSM1800, just replace the U3302 detection with U3401 detection.
Table 9-7 describes the signals in the circuit diagram in this section.
Table 9-7
Description of the signals in the circuit diagram in this section
Signal
Description
Reference Measurement
or Wave Form
VREG_L19_2P85
Supplies power for GPS
2.85 V
VREG_RFRX1
Supplies power for RTR6285A
2.1 V
VREG_RFTX
Supplies power for RTR6285A
2.7 V
VREG_S3
Supplies power for RTR6285A
1.8 V
