The SIM card can't be recongnized on iPhone 6S,we re-installed SIM card many times, but it still won't be recongnized. Now, we need to check the interior of the iPhone 6S.
Use phone opening tools to disassemble the iPhone 6S, take out the iPhone motherboard and put it under the Trinocular Stereo Microscope to check, we found the iPhone baseband power was repaired, because there are a lot of solder patse.
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, one is baseband power supply problem, the other one is capacitance resistance problem.
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 by QUICK 861DW hot air rework station.
Now, the power supply pin of the SIM card
is measured again by digital multimeter, the voltage is normal.
Reinstall the iPhone 6 and insert SIM cart
to test, the card can be recognized now.
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