Huawei P20 - Maintenance Process (Reception)

EML-L29V100R001 Advanced Maintenance Manual V2.1
INTERNAL
2019-6-25
Huawei Confidential
Page 64 of 67
Signal flow in the UHB B7/B38/B40/B41 transmission circuit: U3301 → U3601 → U3501 → U3701 →
Z3701 (diplexer) → J3703 → antenna spring
4.19.3 Maintenance Process (Reception)
Replace RF IC U3301
Check whether the RF
connection cable is
normal and whether the
antenna spring is in good
contact
End
Re-solder the circuit
Replace U3801
End
Yes
Yes
No
No
Yes
No
No
Yes
Yes
No
LTE RF reception failure
Are the
wired specifications
normal?
Is the failure
rectified after the software
is updated to the latest
version?
Is the RF switch normal?
Check the
circuit based on the abnormal
frequency band. Is the circuit
properly soldered?
Replace the
filter based on the abnormal
frequency band. Is the failure
rectified?