There are several reasons can cause iPhone 6 cannot turn on, now we introduce the second situation.
This iPhone 6 used to fal into water and the circuit was interrupted. When removing some capacitors, the leaked current is 200mA. Then we replace power chip U1201, it does not leak any more but it cannot be turned on and the current jumps repeatedly from 110mA to 130mA.
In this case, this fault usually caused by faulty circuits in Touch screen control IC U2402, power chip U1202 and CPU upper board.
Because we have already replaced the power chip, so now we replace its power chip to exclude the solder problem. However, after we replaced the power chip, the turn on current is still jumps repeatedly from 110mA to 130mA.
According experience, the iPhone 6 after water damaged, the damaged upper temporary storage is caused by chip short circuit itself. Observing the temporary storage and the surrounding area of CPU under microscope, we can see explosive tin balls on the surrounding area of upper temporary storage.
We need to remove the upper temporary storage and reassemble it. After completion, iPhone can be turned on normally.
The explosive tin balls on upper temporary storage are shown in picture 1-1.
- When it was first fixed, CPU shield cover was not move, so we did not check the explosive tin balls on it.
- For those chips that have been removed or replaced by other maintenance men, we had better check whether the explosive tin balls appear in CPU or temporary storage chip on the upper board of CPU.