A customer sent us an iPhone 6S to repair, the problem is that iPhone 6S failed to boot after water damaged, and this iPhone 6S was repaired by other repair man, but still not turning on, he want us can help him to solve this problem.
After we received the iPhone 6S, first dissemble iphone with iPhone opening tool , we saw that the
motherboard was flooded with water, we cleaned the water area thoroughly, it
seems that CPU Upper also exist fault. After tested resistance and powered on,
there is no short circuit. Connect the iphone motherboard to the DPS DC power supply, we find the current value is about 240MA.
Test PP-VCC-MIAN with a digital multimeter , exist phenomenon of short
circuit, the resistance is small, only dozens of ohms. Observe carefully, we
found that capacitor next to the WIFI chip was black seriously.
Use QUICK 861DW Hot
Air Station to remove the capacitor, resistance is tested more than 100 ohms, and
the current measured is also more than 100 mA. Due to the large water poured
area, it was found that a capacitor on the iPhone audio
IC also became black seriously, we can check iPhone schematic diagram via WUXINJI Dongle.
After removing the capacitor, measure
PP-VCC-MIAN, then insert the DC power supply again, the current become more than 30 mA. Test multiple power supply,
there is no short circuit, connect to the power supply, we feel a slight heat.
So fumigate rosin in the upper part. It was found that power supply portion was
hotter than other parts. After removing the display power, the current returns
to normal.
Remove the iPhone power IC, test the iPhone motherboard again, now all data tested are normal.
Assemble the iPhone, press the iPhone power button, the iPhone 6S can be turned on successfully now. After entering the IOS, test all functions on iPhone 6S, all works well, the problem has been solved!
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