We got an iPhone 6 to repair, its UMT board shows 0.8mA and doesn’t connect after water damaged. Now vip pro shop team share a phone repair guide for repair it.
Measure its reset data, only 0.8V, and it is nor short circuit. Then remove the iPhone USB management IC (U1700), iPhone display touch IC (U1501) and replace PMU, the resistance data is also normal. Keep going to remove A8 CPU, the reset value is normal 1.8, the value is lower again after installing reset voltage. Now, we can judge the problem is damaged iPhone 6 A8 CPU.
The reset pullup resistance R0206 is 100K, and the voltage becomes 1.6V after the change of the 2.2K resistance.
The upper cover current is a little higher, and the iPhone screen is not displayed when install to test the iPhone 6 device. The power supply required for the measurement screen is normal, connect Ace assistant which shows “please unlock the device”, so it indicates that the system has been entered, and the failure is from CPU. Then PP1V0 is measured short circuit, a few points on CPU are all short circuited. Now, we have to install the CPU back.
Directly connect 1.0V to this point, the current is 350A and the voltage is 0.8V. It seems hopeful, so we connect it with PP1V2_SDRAM directly. We can check it under the 7-45X Trinocular stereo microscope.
After finish the above step, put iPhone A8 CPU back to motherboard, then we restart the iPhone 6, now the iPhone LCD can be display. Enter the IOS, check the iPhone data, all data is preserved.