HUAWEI P40 Pro Wasserschaden Reparatur

Received a HUAWEI P40 Pro water damage phone, as the customer described, the phone with very slight water ingress. However, many function failures happen

• Both the front and the rear camera turn off automatically
• No ringtone function

Fehlersuche

More than two function failures happen, normally, should be caused by the shared power supply or the bus rails with some problem. And by the many years of repair experience, the I2C bus relative chip is corrosive with a higher failure rate.

Besides, based on the P30 repair experience, either only installing the front camera or only installing the rear camera will cause the camera to turn off automatically issue. So we will need to check all the camera circuits, and fix the problem to ensure all the camera circuits are in good condition.

Reparatur-Prozess

First, check the cosmetic of the motherboard under a microscope carefully.

Both the front and rear camera connectors are super clean.

The dock flex cable is also OK.

So the front camera failures might not come from the motherboard, maybe the camera function failure is caused by the little board ringtone correlative part with the problem.

Test!

Detach the dock flex cable (remove the little board) and test, just as we expected, the camera functions are back to normal. So all the issues should be caused by the little board with the problem. 

After detaching the little board, as we can see the flex cable and connector with a little bit of corrosive.

Scratch off the corrosive and then apply some tin to the pin

After that, the issue still remains the same. Let’s measure the diode values on the Dock flex cable, find below two pins’ diode values are 630 and 345, which is abnormal. Usually, should be the same.

Consider the little board with corrosive, so let’s check the whole little board thoroughly.

Remove the shielding cover, and we find the audio amplifier IC. 

Heat with the hot air gun to resolder, then measure the diode value on the connector again, and the diode values of the two pins (I2C4_SCL  and I2C4_SDA) back to normal.

Then assemble the phone to test, both the camera and speaker ringtone function back to normal.

Zusammenfassung

The issue finally gets fixed by resoldering the audio amplifier chip on the little board.

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