How to fix No Service on iphone 6 but SIM Card working normally

If you IPhone 6S has no service with SIM card.

Repair Process

There are IMEI, modem firmware and ICCID in “about iPhone”, but there is not IMEI when dialing *#06#. Checking PCB circuit diagram bitmap we find the testing point of RFFE1 bus is PP3170_RF and PP3171_RF. The testing point is shown in picture 1-51 and the material object is shown in picture 1-52.

Picture 1-51

Picture 1-52

After measuring the diode data of RFFE1 bus, we find the data of PP3171_RF is too large. Teardown baseband CPU to measure the diode data of pin U1 and the data is infinite. Scratch a circuit near pin U1 and connect it to pin U1 with a jump wire, as shown in picture 1-53. After placing the wire, measure the diode data of U1. The data is normal.

Picture 1-53

Doing BGA Reballing on baseband CPU (in picture 1-54), and weld baseband CPU to PCB board.

Picture 1-54

Power on and use an Multimeter oscilloscope to measure the wave of RFFE1_DATA of PP3171_RF under the state of bare board. The wave is normal as shown in picture 1-55.

Picture 1-55

Measure the wave of RFFE1_CLK of PP3170_RF. The wave is normal as shown in picture 1-56.

Picture 1-56

Assemble the board to assembly and enter system to test. Everything is normal. The trouble is removed.