Two solution for iPhone 5SE Circuit Fault

Fault description: iPhone 5SE occurred turning on fault and leakage.
Possibility reason: phone CPU problem or battery short circuit.

According to our ever experience, we doubt there mostly exist circuit problem, which means we need to disassemble it and check the current by DC power supply, like the following PIC shown:

picture 1-1

The battery positive voltage VBATT is first sent to the charging IC-U2300, and the charging IC-U2300 outputs the main power supply VCC_MAIN (same as the battery positive voltage value) to the main power supply U2000 and other related circuits.

The situation is divided into the following:

1. The current is large when supplying power, this situation is usually caused by the positive voltage of the battery or the main power supply, which has short circuited parts. The large current can be quickly found with the rosin method. How to operate: At first, use digital multi-meter to measure the battery positive pole and the main power supply to the ground resistance value, find out the short circuit parts. Use rosin to smoke the iPhone SE main board into white color, add voltage in the short circuit parts, you have to notice that the voltage must be added to the short circuit parts, the voltage is gradually increased from zero, after the short circuited parts is supplied power for a while, it will heat and turn into different color, then you can find the specific components immediately.

2. The iPhone SE device has no response after turning on, first measure whether the main power supply of U2300 is there, if not, you need to replace U2300, if the main power supply is normal, then it means the problem is from the power IC or CPU.

3. The current is small and iPhone is unavailable, measuring whether the voltage of the parts as shown in WUXINJI schematic diagram is normal, as shown in 1-2, if yes, you need to replace the clock crystal Y0600, check and weld several pull resistance of bus circuit will cause small current and iPhone unavailable, these resistance must be replaced instead of short connection, if the above problems are excluded, it should be the iPhone SE CPU  problem, you can install a new CPU to solve.

Picture 1-2