insert the SIM card

Failure Analysis:
(1), the mobile phone point of contact within the area of the device are small and the contact pressure can not be too much, and some mobile phone SIM card connector of the structural design is not quite rational, so prone to this failure.
(2) of the current SIM card both 5V cards, there are 3V card here involves a SIM card power conversion problems, but also the need for a step-up from the 3V to 5V step-up circuit.
Examination and treatment:
(1) SIM card is good contact between reed? If the problem can be cleaned or carefully corrected SIM card reed;
(2) SIM card operating voltage, or step-up circuit normal?
(3) and SIM-related detection and control circuit whether the problem? In particular whether the cold solder joint?
(4) software data have an error or part of the data loss can be re-write a software to try?

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