Malfunction Phenomenon
The phone can’t be turned on accompanied by a current leakage issue.
Trouble Shooting
For the iPhone 8 Plus Not Turn On with Current Leakage issue.
First, take out the motherboard and connect the battery connector with DC power supplies, the reading on the ammeter is 0.9MA, which is abnormal. But the measured diode value is normal.
So we continue to measure the diode value of PP_VCC_MAIN, the measured value is abnormal, which indicates that the fault is related to the relevant PP_VCC_MAIN circuit.
So we can find out the faulty component with the rosin detecting method.
Apply the smoke rosin on the relevant circuit on PP_VCC_MAIN, then apply power on the motherboard, the rosin on the backlight IC U5600 gets melted immediately when connected with the DC power supply.
It can be concluded that the fault is related to U5600.
After replacing U5600, then get the motherboard mounted and display assembly installed, press the power button to power on, the phone can start up normally, problem resolved.
iPhone X Motherboard Repair Course
