Practical Guide: Repair iPhone 6S won’t boot and power leakage fault

Just like other iPhone models, if the iPhone shows leakage when it was supplied power, it’s usually because BATT_VCC (battery voltage) or VCC_MAIN (main power supply) these two circuit lines short circuit, the other case is that when supply power on it, but it is not leakage. After iPhone is turned on, its standby current is about 100mA, this case mostly was caused by iPhone USB control IC is damaged.

IPHONE NAND TEST FIXTURE_proc

The iPhone 6S battery voltage passes the charge IC and then output the main power supply VCC_MAIN.

If provide power on iPhone but is shows leakage or large current, then we need to use Digital Multimeter  to measure the diode data of BATT_VCC and VCC_MAIN! If there is a short circuit, we can apply some rosin on the iPhone motherboard component, use hot air gun to smoke it, and supply voltage on short circuit line, the voltage starting from 0 and gradually increasing, and then you can find the short circuit parts. In this part, we have to add voltage on short circuit place.

fx067_proc

The other iPhone power leakage situation is that when you provide power on it, it won’t leak, but after you press the iPhone power button, the leakage or large current fault happens. This fault is because there is a leakage component on the circuit lines that was output by power supply IC. In this case, you need to measure the diode data of each circuit line to find the one that’s leaking. If the leakage is large, you can use rosin methods to find the short circuit parts (the methods the same as above).

In addition to the leakage of the situation caused iPhone no boot, there are other reasons cause iPhone won’t boot.

  1. No response when booting. Measure whether these is a VCC_MAIN, if not, replace the charge IC U2300, if VCC_MAIN is normal, and then replace the power IC U2000.
  2. Stuck on White Apple logo when booting. Replace the USB control IC U4500 charge IC U2300. If the fault still exists after replacement, then it should be the CPU or NAND flash problem, you can re-install the iPhone NAND flash.
  3. Stuck on Dozens of MA when booting. This fault mostly caused by CPU or iPhone NAND flash virtual welding or damaged. For water damaged iPhone, you can replace power IC/ audio IC/ compass IC/ USB control IC/ charge IC.
  4. Reports different iTunes error. If it reports iTunes error 4005/ 4014/ 9/ 14/ 40, usually it is caused by iPhone Nand flash or iPhone CPU. Because the iPhone CPU is unable to weld, you can re-install it or replace the Nand flash, and then flash it again. If it reports iTunes error 1/47/48/50, usually it is baseband part problem; you can re-install iPhone baseband CPU and power IC. Moreover, damaged compass will cause iTunes error 4013, just replace the compass IC. If it reports iTunes error 56, mostly it’s caused by NFC module virtual welding or damaged. If baseband power IC is virtual welding, you can re-install or replace it.

 

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