Model GC318
L3 Service Manual
1. Check whether the SIM card is damaged
2. The component of card slot is damaged or not; whether the indication of inserting SIM card is correct or not
3. Check whether the power supply to SIM card is connected or not
1. Check whether the SIM card is clear enough to connect to the PCBA
2. Change another SIM card, if it can be detected, it proves that the previous SIM card is damaged.
CPU
1. If there is no issue about the card slot itself, then you have to check the around resistance and capacitance
soldering properly or not.
2.If the soldering has problem, you have to replace the replace or re-soldering .Finally you have to check the
signal SIM-CLK,SIM-DATA,SIM-RST-N(from CPU) and the voltage .
3. If the soldering has no issue, you have to check the signal path.
Once there is no problem about above 3 points, you have to re-soldering or replace the CPU.
