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Thread: iPhone 3gs replacement back does not detect Sim inserted

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So I bought a pre built back with the battery, dock, wifi antenna etc. Ready to put a logic board and screen and go. So I put in a known
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  1. #1
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    Default iPhone 3gs replacement back does not detect Sim inserted
    So I bought a pre built back with the battery, dock, wifi antenna etc. Ready to put a logic board and screen and go. So I put in a known good 3GS Jailbreak to 5.01 and unlocked logic board, put the screen on, power it up and everything worked fine. When I inserted the Sim the iPhone could not detect that it was inserted. Put the board in any other back and it works fine. Same Sim; Same tray. My question is how is the Sim detected? I thought it was all on the logic board.

    Any ideas?

    Thanks.
    Last edited by mateo1961; 05-08-2012 at 03:20 PM.

  2. #2
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    OK after 20 Sim trays I was able to find two that would let the Sim be detected.

    I was just wondering how the Sim is detected. Is it read through the six connectors or is there another mechanism that detects a Sim tray is inserted then the card is read?
    I need to better understand the mechanism so that I can fix the logic board so it would detect the Sim every time with any tray.


    Thanks.

  3. #3
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    Try this. Make SIM Tray longer. Take a SIM Tray that does not work. Add a bit of tape, plastic, paper whatever you like and add it to the very end of the SIM Tray, to make it about a half mm longer.

    Why this would work. You new back is out of specification, not perfect size. Maybe a slightly longer SIM Tray will now press the copper wire switch deep in the SIM Bay to get the iPhone to read the SIM Card.

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    mateo1961 (05-10-2012)

  5. #4
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    Thank you for the response.

    I had always thought that the wire was a spring to pop the tray out. LOL.
    So that wire on the bottom when no tray is in makes a short with the other wire. When a tray that does not work is inserted it barely touches the wire and does not open the wire. When a tray that works is inserted it breaks that connection.


    That was the information I was looking for. Thanks.

  6. #5
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    To close this thread, I was able to loosen the screws on the logic board and gently push the board forward enough that now any tray can be read.

    Thanks

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