The SIM Card circuit of Nokia 5730 Xpressmusic, this guide can be used to troubleshoot and repair Insert SIM Card problem when occurs. The SIM card connection is rarely the same as of some any Nokia mobile phones handsets, The 5730 does not have a SIM filter IC unlike others do have.
The SIM data, clock and reset signals is feeds directly from the PMIC (power ic) located at the right bottom of the main pcb board. Each signals used bypass capacitors to ground lines which is mounted behind the SIM card connector socket. The SIM supply voltage (VSIM) used a filter coil mounted located near at the SIM socket.
You can trace each individual lines paths during hardware repair. You may start from checking the supply voltage first by checking the filter coil and the line paths across to it from the VSIM capacitor near to the PMIC (power ic).
Check the Data, Clock and Reset line paths through to each capacitors.
For further deeper troubleshooting check it here and learn how the SIM circuit works.