U8815
Maintenance Manual
9 Principles and Failure Analysis
Issue 1.0 (2012-02-13)
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
41
Figure 9-27
Troubleshooting process for receiving 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.)
Check U3404.
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
receiving channel
End
Y
Check
whether signals on pins
1 and 8 of U3401 are normal and the
maximum insertion loss is smaller
than or equal to 2.3 dB.
NOTE
Check the control signals of U3202 switch using a multimeter or an oscilloscope. The truth table for
control signals is as follows:
Table 9-6 describes truths for control signals.