Malfunction Phenomenon
iPhone XR no service when we insert the sim card, and the IMEI was normal in settings, and when we press “*#06#”, the IMEI was also normal.
Trouble Shooting
Because the IMEI was normal, according to our experience, the problem was from the RF(Radio Frequency) circuit. We disassembled the phone and checked the diode value on the power line for the RF circuit. Then we found the diode value on the capacitor C416_K was 0.
It’s on the power line PP_3V15_LDO1_VFE_AUX from BBPMU to the power amplifier ICs PA_UHB_K, PA_HB_K, PA_LB_K. We removed the capacitors on the rail, but it was still shorted, it means the short was from the chips.
Then we have to remove one by one. When we removed the chip PA_HB_K, the short was disappeared, then we replaced another chip PA_HB_K and put other caps and chip back.
And tested again, the service was back to normal.
Go to iPhone Motherboard Repair Course to Learn More
