Xiaomi 9mobileNo signal fault repair

Machine model: Xiaomi 9
Customer description: After Fall hard, the cell phone has no signal.
Test results: The mobile phone can be turned on, all functions are normal, reading all Baseband IMEI, and inserting the SIM card no serviecs.
Fault analysis: The fault caused by Fall hard should be caused by Inveracious Soldering pad break off, a chip component of signal power amplifier.
Open the Xinzhizao Soft software, find the drawing of Xiaomi 9, and check the signal circuit of the motherboard.

Xiaomi 9mobileNo signal failure repair Figure 1.

First, observe whether the chips and components in the signal part are obviously damaged, and then carry out Repeat welding and Repeat welding installation tests on the chips in this area, and the fault remains. Then, the signal chip is repaired after Reballing,Reballing Reballing power amplifier.