Huawei Y300 Maintenance Manual page 55

Y300 Maintenance Manual
Figure 9-28 Troubleshooting process when the Y300 fails to receive signals
NOTE
Use the multimeter or oscilloscope to check that U3202's control signals are normal. Table 9-2 is the
truth table of the control signals.
Table 9-2 Truth table of the control signals
GSM850 RX
GSM900 RX
GSM1800 RX
Issue 1.0 (2013-01-24)
The WCDMA 2100 MHz
receive channel is faulty.
Check U3201 before the
RF cable is connected.
Are pin 1 and pin 2
of U3201 properly
connected?
Y
Are the control signals of
U3302 normal? (See
Table 9-2 for the truth
table.)
Y
Are signals output from pin 1
and pin 8 of U3304 normal?
(The insertion loss must not
exceed 2.3 dB.)
Y
Are I/Q signals and power
voltage of U3801 normal?
Y
Check the U401.
Y
End
Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
9 Principles and Failure Analysis
N
Check the U3201.
N
Check the U3302 and
U401.
N
Check the U3304.
N
Check the U3801.
0 1
0 1
0 0
1 0
0 0
1 0
50