Maintenance Principle (Transmission); Maintenance Process (Reception) - Huawei P20 Maintenance Manual

4.18.2 Maintenance Principle (Transmission)

Signal flow in the GSM850/GSM900 transmission circuit: U3301 → U3402 → Z3401 (LPF) → U3501
(module) → U3701 (DPDT) → Z3701 (diplexer) → J3703 → antenna spring
Signal flow in the GSM1800/GSM1900 transmission circuit: U3301 → U3402 → U3401 → U3702 →
Z3701 (diplexer) → J3703 → antenna spring

4.18.3 Maintenance Process (Reception)

The maintenance process is the same as that for WCDMA B5/B8, WCDMA B2, and LTE B3 reception
failures.
2019-6-25
EML-L29V100R001 Advanced Maintenance Manual V2.1
Huawei Confidential
INTERNAL
Page 60 of 67