How to Repair iPhone 6S SIM Card Identification Failure

We want to fix the iPhone 6S, the main failure is that it can't recognize SIM card. The first step after receiving the call is to remove and check carefully. Before the iPhone is repaired, the repaired area is the baseband power, and there's a lot of solder paste in it.

Use digital multimeter to measure the voltage of each pin of the socket at the moment of power-on, all the SIM-RST SIM-CLK SIM-DATA have instantaneous voltage, only SIM-VCC does not.

According to past repair experience, there are 2 problems in the power supply of SIM card:

1. baseband power supply;

2. capacitance resistance.

The baseband power supply has been repaired, without considering power supply. It should be a small capacitor or a small resistor problem.

By checking the WUXINJI circuit diagram, it is found that the small capacitance and the resistance are under the shield cover, carefully cut off a part of the shield, and observe the small capacitance under the Trinocular Stereo Microscope. It is found that the color of a small capacitor is a bit different, so we remove the damaged one.

Now, the power supply pin of the SIM card is measured again, the voltage is normal.

Reinstall the iPhone 6 and insert SIM cart to test, the card can be recognized, and other functions are also tested OK.

Summary: a lot of repairmen choose to replace parts, no more thorough understanding of the principle of the mobile phone, and they do not know how to find out after replacing a few IC, in fact, a lot of faults are in small capacitors and resistors or inductors.

If you want to get more professional cell phone repair tutorials read on www.vipfixphone.com