iPhone XS Max restarts from time to time for repair

iPhone XS Max restarts from time to time for repair

Machine model: iPhone XS Max

Trouble phenomenon: restart from time to time

Customers use restart normally, check the restart log and report an error userspace watchdog timeout (WDT).

Repair process:
The inspection found that the battery communication is normal and the test function is normal. The fault may be caused by Accessories. (There are only two WDT maintenance directions. The first is battery data and microphone, and the second is Accessories.microphone is divided into three failure points: 1.Accessories 2. Boot FPC 3.microphone FPC)
It still restarts after replacing the assembly shell and earpiece FPC. Then the fault is the motherboard, and there is no appearance problem on the motherboard visually. Use multimeter to measure the test points.

iPhone XS Max restarts from time to time for repair figure 1.

iPhone XS Max restarts from time to time for repair figure 2.
Inductor around FPC does not have Inveracious Soldering, but there is a crack in the middle of charging connector BTB connector, and the location of the crack is just the bus of main microphone and VCC line. Replace FPC BTB connector directly, and the test will not restart after replacement.

iPhone XS Max restarts from time to time for repair figure 3.

iPhone XS Max restarts from time to time for repair figure 4.

iPhone XS Max restarts from time to time for repair figure 5.
Maintenance ideas:
1. see if the battery communication is normal. if it is not normal, then the triangular tube or BTB connector is deformed.
2. Replace original charging connector, boot FPC,earpiece FPC in turn (most of the problems with boot FPC are FPC and the damage when replacing the rear case glass)
3. Check whether charging connector FPC has any problems in appearance and whether the surrounding Inductor is Inveracious Soldering.

4. If it can’t be repaired, try replacing the battery directly.