HUAWEI P40 Repair Cases Sharing

HUAWEI P40 repair cases sharing.

Model: P40

Announced: 2020, March 26

Case 1. The cameras turn off automatically and Wi-Fi cannot work

Received the phone and tested it, as the customer described the phone camera turns off automatically, and try to open the Wi-Fi button but it turned to grey shortly.

Troubleshooting: based on the repair experience and the circuit block diagrams of P40. The Wi-Fi and camera share a 1.8V voltage. When the main camera with a problem, the power supply for the Wi-Fi will be pulled down. So the Wi-Fi issue might be caused by the camera.

Disconnect the main camera flex cable only and remain the rest camera connectors connected, then test the camera and Wi-Fi functions again. 

Now, the camera and Wi-Fi functions work fine

So the issue should be caused by the main camera module damage, the issue can be resolved by replacing the main camera with a new one.

REWA ACADEMY

Case 2. No Boot After Dropping Damage

The drop damage causes the SoC upper layer short damage. Replace it with a new one, then the phone can boot normally.

REWA ACADEMY

Case 3. No Wi-Fi Issue Caused by Drop Damage

For the Wi-Fi issue caused by drop damage, there’s a high chance it’s the Wi-fi chip gets poor soldering or the Wi-Fi crystal oscillator with inner line broken.

First, let’s check the motherboard under the microscope, as we can see there’s a deformation on the shielding cover.

The shielding cover with some damaged signs, let’s remove the shielding cover and check carefully.

After checking we can see the crystal oscillator is cracked already. Replace the crystal with a new one, then assemble the phone to test, the Wi-Fi function back to normal.

（Tips: for the removed shielding cover, if you have a new or good shielding cover you can solder it back with medium-temperature solder paste + soldering iron station）