Maintenance Process (Reception) - Huawei P20 Maintenance Manual

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)

circuit based on the abnormal
frequency band. Is the circuit
frequency band. Is the failure
2019-6-25
EML-L29V100R001 Advanced Maintenance Manual V2.1
LTE RF reception failure
Are the
wired specifications
normal?
No
Is the failure
rectified after the software
is updated to the latest
version?
No
Check the
properly soldered?
Yes
Is the RF switch normal?
Yes
Replace the
filter based on the abnormal
rectified?
No
Replace RF IC U3301
Yes
Yes
No
No
Yes
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INTERNAL
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
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