iPhone 7 white apple restart repair

Machine model: iPhone 7
Fault symptom: the mobile phone Stuck on Apple logo restarts

iPhone 7 white apple restart repair Figure 1.

Fault analysis:Stuck on Apple logo restart Baseband has many problems in the 7th generation machines.
Maintenance process: observe that the current is 600mA or 800 Ma after switch and restar or so.

iPhone 7 white apple restart repair Figure 2.

Anyone who has repaired the Baseband problem will know that the current of Baseband problem is 300 or 500mA or so restart. When the motherboard is removed, the boot current can normally enter the system as soon as it reaches the 1A or so screen. It seems that the Baseband problem may be the cause.

After investigation, it was found that as long as the boot FPC was buckled, the boot could not be started normally, and the failure of replacing the boot FPC remained the same. Check that the motherboard has traces of water damage corrode on FPC.

iPhone 7 white apple restart repair Figure 3.

OverLoad nd test the fault again, and measure the ground value of BTB connector No.11 pin OverLoad 22601 OverLoad 6901.

iPhone 7 white apple restart repair Figure 4.

According to the drawing, it can be known that pin is I2C bus signal which is connected to I2C bus signal through FL4732. The signal disconnection is definitely wrong. Check PCB Boardview to find the connected components.

iPhone 7 white apple restart repair Figure 5.

iPhone 7 white apple restart repair Figure 6.

The motherboard inspection found that there was diode value at one end of FL4732 Inductor and OverLoad at the other end, and the original of water damage corrode was reprocessed.