iPhone 6 is water-damaged and cannot be turned on


This iPhone’s problem is turn on failure. The customer said water flew in it before and he tore down it to fix the touch flex cable and some parts of Wi-Fi. After using for some time, it cannot be turned on. Tearing it down and we can see that the waterproof label discolored, as shown in picture 6-26.

Picture 6-26

The waterproof label in normal iPhone is white, as shown in picture 6-27.

Picture 6-27

Repair Process

After plugging adjustable dc power supply, it shows large current. We judge that the voltage of standby circuit is short circuit. Use the diode gear of multimeter to measure it and find that PP_VCC_MAIN is short circuit. Observing the motherboard carefully, we find the capacitor C5202_RF near Wi-Fi chip is a little dark and its tin plate drops a little. Remove C5202_RF (picture 6-28) and measure the voltage of PP_VCC_MAIN, which is no longer short circuit.

Picture 6-28

Energize iPhone and turn it on. Now it can get into IOS system normally. We think it recovers now, but after using for a while, iPhone generates heat badly and the battery drains quickly. Misfortunes never come alone. For those iPhones that can be turned on and get into IOS system normally but generates heat badly and the battery drains quickly, they must have somewhere that is short circuit at the subordinate circuits. The troubleshoot way is to test each function in IOS system. The abnormal part is the faulty point. After testing each function, we find that the compass function is abnormal. Every time we open compass, we need to calibrate it, as shown in picture 6-29.

Picture 6-29


Although it is calibrated, the directions it shows are wrong, as shown in picture 6-30.

Picture 6-30

At the same time, we test the gravity sense function and it is normal, as shown in picture 6-31 and 32.

Picture 6-31

Picture 6-32

Based on the tested results, we conclude that the problems which cause high heat and quick battery drain happen at the compass circuits. Use multimeter to measure the power supply of compass and find that PP3V0_IMU voltage is short circuit, as shown in picture 6-33.

Picture 6-33

Power supply chip outputs PP3V0_IMU and it is filtered by capacitor C1902. Then it is offered to compass chip U1901 (NONSTUFF on C1902 is not installed).
The circuit of compass chip is shown in picture 6-34.

There are several possibilities that cause short circuit of PP3V0_IMU voltage.
（1）The power supply chip is damaged.
（2）C1902 is damaged.
（3）The power supply chip is damaged.

Picture 6-34

Under the repair rules the simple first and the complicated later, remove C1902, as shown in picture 6-35.

Picture 6-35

Measure the diode data of PP3V0_IMU again. It recovers to normal one 455, as shown in picture 6-36.

Picture 6-36

Reassemble iPhone and turn it on to enter IOS system. IPhone does not generate heat after using for a while. Compass function recovers. Trouble is removed.

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