Huawei mate 30 Pro mobile phone has no signal repair

Machine model: Huawei mate 30 Pro
Fault phenomenon:
The machine was collected by peers. After changing a new screen, the phone turned on and found that there was no signal on the phone. Both Baseband and IMEI can also read the card. Manual search for operators failed.

Huawei mate 30 Pro mobile phone has no signal repair Figure 1.

Fault analysis:
For Kirin models, most of the search operators failed because the working conditions of IF were not met.
Maintenance process:
The IF was replaced first, and the fault is still the same.
At this time, we have two directions: first, the working conditions of IF are not satisfied;The second is caused by Inveracious Soldering.Remove IF, measure the 8-way communication between pin at the bottom of IF and CPU, and find that diode value is normal.

Huawei mate 30 Pro mobile phone has no signal repair Figure 2.

Huawei mate 30 Pro mobile phone has no signal repair Figure 3.

Huawei mate 30 Pro mobile phone has no signal repair Figure 4.

Huawei mate 30 Pro mobile phone has no signal repair Figure 5.

Huawei mate 30 Pro mobile phone has no signal repair Figure 6.

Huawei mate 30 Pro mobile phone has no signal repair Figure 7.

Therefore,IF, CPU and their communication are basically excluded. After looking at the drawing of CPU module, it is found that there are two circuits under the communication circuit with IF. The first [pmuo ﹣ RF1 ﹣ CLK] is the main power supply of CPU.

Huawei mate 30 Pro mobile phone has no signal repair figure 8.

Huawei mate 30 Pro mobile phone has no signal repair Figure9.

Remove the l601 measurement pass CPU with diode value 370 or so.

Huawei mate 30 Pro mobile phone has no signal repair Figure 10.

The other end of the test is ol, because it needs to connect to the main power supply through a coupling Capacitor, and make up for Inductor l601.

Huawei mate 30 Pro mobile phone has no signal repair Figure 11.

Huawei mate 30 Pro mobile phone has no signal repair Figure 12.

Test c1226 is connected to one end of the main power supply diode value and 400 or so. Combined with the main board, the screen has been changed, and it must have fallen before, and there is no deformation area on the main board, so the main power supply or Inveracious Soldering in the middle layer is basically locked.