Rf Failure (Gsm); Maintenance Process (Transmission) - Huawei P20 Maintenance Manual

4.18 RF Failure (GSM)

4.18.1 Maintenance Process (Transmission)

rectified after the software is updated to
output RF signals of U3702 based on
the non-signaling transmission of the frequency
corresponding diplexers U3702 and
U3401 based on the abnormal frequency band.
2019-6-25
EML-L29V100R001 Advanced Maintenance Manual V2.1
GSM RF transmission failure
Are the
wired specifications
normal?
No
Is the failure
the latest version?
No
Is the RF PA power
supply normal?
Yes
Spot-check the
band. Are the signals
normal?
Yes
Replace the
Is the failure
rectified?
No
Is the failure rectified after the
related circuit is replaced?
No
Replace U3801
Huawei Confidential
Yes
connection cable is normal
spring is in good contact
Yes
No
Follow the power supply
maintenance procedure to
No
Yes
Yes
Yes
No
Replace U3301
INTERNAL
Check whether the RF
and whether the antenna
End
rectify the failure
Replace U3401 and
U3702
End
End
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