Have you ever met the iPhone 6s into the water and then had no service even though you dry the water. At this time ,the iPhone 6s can not be used to communicate with people, this is frustrating. So, what should we do to fix it? Viprog tells you.
First, Enter system to test and iPhone displays no service with SIM card . In “settings” we can see operator options but no service. That the operator options shows suggests trouble does not in signal reception circuit but in signal emission circuit. After teardown, we find the motherboard ,has been watered and corroded, as shown in picture 1-1.
Second, clean the corroded places and test the power supply of each chip. We find the power supply diode data of 2G amplifier chip is infinite. After checking the circuit diagram, we know the power starts from PP_VCC_MAIN and then pass insurance resistance R4501_RF to 2G amplifier at last, as shown in picture 1-2 and The location of resistance R4501_RF in PCB bitmap is shown in picture 1-3.
Then, Assemble the resistance R4501_RF and enter system to test. The trouble is still the same. Use a 10cm jump wire acting as a phantom antenna to check where is damaged exactly. The enameled wire starts from the 2G emission chip of RF chip, as shown in picture 1-4.
Finally, after the above steps, enter system to test and iPhone still displays no emission signal. We can conclude the RF chip is broken. Replace RF chip and the trouble is removed.