How to change or clean Sony Ericsson W890i SIM card reading device

Andy, you can clean the contacts on the Sim card reader, either with isopropyl alcohol or a pencil eraser. It is possible that the pins are not making contact with the card, try to carefully bend them up. Worst case scenario, replace the Sim card module, which is available at places like this. Not to expensive or to difficult to change. No reason to worry about soldering or replacing the logic board. Always start with the easy and inexpensive items first. If you need the service manuals for your phone you can find those on here. Hope this helps, good luck.