Fault Description: iPhone 6S won't turn on after water damaged.
After we received it, we use the opening pry tools to disassemble it, and try to power it on, while we need to take out the iPhone motherboard to check whether it has a short circuit faults. Before that, the water area of iPhone motherboard should be cleaned up.
After observing the iPhone motherboard, we found the upper of the iPhone CPU is deformed, measure it with digital multimeter, the iPhone CPU upper doesn't shorted.
Connect iPhone motherboard to the DC power supply, the stand-by current is about 0.24A. Measure the diode data of PP_VCC_MAIN, the data tested is lower than the normal value。
Put iPhone motherboard under the Trinocular Integrated Microscope to check, we found the capacitor next to the iPhone WIFI IC was seriously blackened. Open the WUXINJI Dongle to check iPhone schematic diagram, so we can know the physical position on the iPhone motherboard.
Pic 1
Remove it directly, and then measure it again, now the data tested has more than 100, and the stand-by current tested also is more than 100mA.
Carefully observe the iPhone motherboard again, we found that there is a capacitor next to the iPhone audio IC also was seriously blackened. Remove it directly, and then measure it again, now the data for PP_VCC_MAIN is more than 300, and the stand-by current turns to 30mA, but the upper part of the iPhone motherboard is slightly hot.
Use rosin method to find out the faulty part, we found the temperature of the iPhone display power part is higher than others. Use QUICK 861DW rework station to remove this iPhone display power IC, and then connect iPhone motherboard to the DC power supply to measure it, now the stand-by current is back to normal.
Pic 2
Install the new iPhone display power IC, and then assemble the iPhone 6S. Test it, now the iPhone 6S can be turned on successfully.
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