IPhone 11 does not boot (main power supply is short-circuited, U2 is damaged)

IPhone 11 does not boot (main power supply is short-circuited, U2 is damaged).

A second-repaired iPhone 11 failed to turn on. The second repair machine means that the last one was not repaired, and then it was sent to us for quick repair, which proves that our maintenance master is quite hard-core, so let’s see how hard the professional maintenance technology of the maintenance master is!

[Fault model] iPhone 11

[Fault phenomenon] No boot.

[Maintenance process] I received a machine sent by my peers for repair, the model is iPhone 11, and the fault is that it does not turn on.

IPhone 11 does not turn on Figure 1

This is a second-repaired machine, which was not repaired at home. It was sent here for repair. After disassembling the machine, it was found that it was electrified and the main power supply was short-circuited. There is no short circuit in the burner. Take off the shielding cover and observe carefully. It is found that there is a capacitor next to the speaker power amplifier that is a little black. Just deduct the capacitor and start the test. At this time, the resistance of the main power supply has recovered to more than 300.

IPhone 11 does not turn on Figure 2

The power-on test found that the standby current was normal, which triggered a direct jump of 400mA. If this current is used, we generally consider that there is a short circuit in the three-terminal power supply, but such a large current should be directly felt by hand. After taking an infrared photo, it was found that U2 was hot, and it was directly removed before triggering.

IPhone 11 does not turn on Figure 3

Take-off current returns to normal, and it can be turned on after U2 is replaced. If the current is normal, it can be turned on, and it can successfully enter the system after the screen is buckled.

[Maintenance Result] Install the motherboard into the shell.mobile phone It can be turned on normally, and the functions of WiFi, Bluetooth, voice, charging, fingerprint, taking photos and making phone calls are all normal, so the maintenance is over.