U8950 Maintenance Guide V1.0
10 Principles and Failure Analysis
2012-10-22
Huawei Proprietary and Confidential
68
IMT/PCS/CELL
reception failure
Do not connect the
RF cable.
Check J3201.
Check the signals on U3301
pin 2 and pin 5 are normal.
The attenuation must less
than 2.3 dB.
Check U3202
and U401.
Check U3301.
Y
N
Y
N
N
Check U201.
End
Y
Y
Y
Check U3301.
N
Check whether the IQ signals on
U3801 pins 11, 12, 13, and 14 are
normal and whether the power supply
voltage is about 2.6 V.
Check whether U3202 RF
switch control signals are
normal.
Check whether J3201 pin1
and pin 2 are connected.
NOTE
Check the control signals of U3202 switch using a multimeter or oscilloscope. The truth table for control
signals is as follows:
TRX_IMT
TRX_PCS
TRX_CELL
ANT0
√
∕
∕
ANT1
∕
√
∕
ANT2
∕
∕
√
In W1900, just replace the U3304 detection with U4104 detection.
In GSM, just replace the U3304 detection with U3404 detection.
