iPhone 7 Can’t Boot Up with Current Value 200mA

iPhone 7 Can’t Boot Up with Current Value 200mA

Malfunction Phenomenon

The phone can’ t boot up after charging with car charging system. We measure the boot current by connecting with power supply machine. It shows 200mA, which is much higher than the normal value.

Trouble Shooting

Part of the circuit is shorted will make the current higher than normal. For car charger, some non-original chargers and data cables of power bank don’t come with over-current protection, which will cause great damage to the chip. What’s more, long time usage will also leads to the malfunction of USB IC. As for the phone was damaged after using car charging, according to our experience, firstly we can check the USB circuit.

We take down USB IC. Connect the motherboard with power supply machine, the boot current gets normal. However, the screen stuck in Apple logo and will restart again after power on. This is normal because CPU needs to check the USB IC via BUS. Since the USB IC is abnormal, CPU would reset and keep on detecting the USB IC.

We replace with a new USB IC. Then connect with power supply machine and reboot. Faulty cleared.

iPhone 7 Motherboard Repair Course