Trouble Phenomenon

The customer said that his iPhone 5S battery is unendurable and drains quickly

Repair Process

Tear down the iPhone and plug adjustable power supply to energize the motherboard. Trigger it on and enter IOS. Press the power button and find that the current is 332mA when the screen is off. The normal iPhone screen turns off after being turned on for a while and then the current changes to sleep mode, which will return to 0mA and jump to 100mA. However, when this iPhone screen is off, the smallest current is 332mA, which suggests an obvious electricity leakage.

Judging from repair experience, if iPhones can be turned on, but battery drains quickly, we have to think about the USB management chip U2 that is very likely to cause such a problem. However, during the repair process, we must consider whether there is electricity leakage after being offered power. After excluding electricity leakage, USB management chip can be considered.

Plug adjustable power supply to energize the motherboard again and the current is 0mA, which suggests that there is no electricity leakage. The faulty point is USB management chip.

Remove the USB management chip U2 and turn motherboard on to test standby current and the sleep current. They are normal. When the battery is full, test it and it can standby for a whole day. Trouble is removed.