Réparation du HUAWEI Mate 40 Pro endommagé par une chute

Received a serious drop damaged HUAWEI Mate 40 Pro

Modèle : Mate 40 Pro

Annoncé : 2020, 22 octobre

Phénomène de défaut

Because of the quarrel, the wife smashes the mobile phone in anger, felt regret after calming down, then sends the phone to our repair shop and wishes the phone can be fixed. 

• Both the front screen and back cover are cracked
• The phone cannot be booted

Dépannage

Remove the back cover and protect the cameras with the sticker

Then take out the motherboard and check the cosmetic carefully, find the motherboard was deformed

Even the shielding cover can be taken off easily.

A lot of inductors around the chip are loose and dropped

Remove the inductors directly and also check carefully to see if there are still other poor soldering components and chips. After checking, then try to boot with the DC power supply connected.

Luckily, there is no current leakage. This means there is a higher chance to get the phone fixed.

Then let’s check the conditions of the CPU and the UFS chip, remove the thermal grease, and clean with PCB cleaner, the CPU and UFS chip looks fine.

So, let’s put back the inductors one by one. Then check the boot current again.

The phone still cannot be booted.

Carefully check with the thermal camera, and multimeter and finally find out there is an inductor is damaged.

Replace the below inductor with a new one then test again, and the boot current is back to normal.

Temporarily assemble the phone and trigger the boot process, boot current curve is normal, and can feel the vibration of the phone. But no display…

Based on the repair experience, the no display should be caused by the poor soldering of the two layers of the motherboard. Measure the diode value on the display and touch connector, it’s higher than normal value

Recombine the two layers of the motherboard and test again, the phone can be booted normally and the display function is also back to normal

Résumé

The issue was fixed by

1. solder back the missing and loosen inductors
2. replace another damaged inductor (we find it with the help of the multimeter and thermal imager)
3. recombine the two layers of the motherboard

No matter what happened, try your best to control your temper and don’t be angry. If you cannot help to get angry at least don’t smash your phone. 

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