iMac SD reader does not write or format or delete data - it only reads

Discussion in 'iMac' started by hulaprissy, Mar 19, 2012.

  1. hulaprissy macrumors newbie

    Mar 19, 2012
    I have an 21.5" iMac (Intel) which runs OS 10.6.8, its SD card reader does not WRITE. It says read-only in info.
    I used other SD cards to try - all the same.
    It used to write before, few months ago, it stopped writing - no deleting, no adding in anything
    I opened Disk Utility, its erase, repair ... etc functions are all disabled - so I cannot format it.

    So I used used an external (USB) card reader to try, it works perfectly fine with reading and WRITING
    Disk Utility also works fine with the SD cards which are connected through the externer card reader.

    What is wrong with the 21.5" Intel iMac's SD card reader?
    What can I do...???

    Many thanks!


    PS: I recognise that many people have the same problem. I also called Mac and they guided me to do a PRAM reset. It still does not help......!!! I am getting quite frustrated.:confused:
  2. itsmrjon macrumors regular

    Jun 11, 2011
  3. BeamWalker macrumors 6502a


    Dec 18, 2009
    This is a common problem through the range of Macs I am using (iMac 2009, iMac 2011, MBP 2010 and MBP 2011). It really is a big pain. I have no idea what is really going on either. Normally it works when I put the write lock switch in the middle. There are tons of People in the Apple forums who are experiencing similar problems. I really wish Apple will sort that out in future Macs.
  4. hulaprissy thread starter macrumors newbie

    Mar 19, 2012
    Yes. I am sure the card is not locked when it is inserted.

    If thats a common problem, then I will try pushing the lock in the middle and see if it works.... :(

    Thanks for your suggestions!
  5. swordfish5736 macrumors 68000


    Jun 29, 2007
  6. leroidys macrumors newbie

    Oct 5, 2012
    Faulty iMac card reader

    I have the same problem on my iMac (Intel 21.5"). Most likely it is a problem with your iMac's SD card reader.

    Shine a strong light into your Mac's SD card reader: you will be able to see a tiny, brass-coloured latch on the narrow floor of the slot. If your iMac has the same problem as mine, then that latch will be sitting in the 'down' position (ie inserting the SD card does nothing to change its position).

    Normally the latch sits in the 'up' position and is depressed when an SD card is inserted. With an unlocked SD card, there is a minuscule space for the latch to pop back into the 'up' position. With a locked SD card, the slider on the card blocks that minuscule space, thus telling the computer that the SD card is in locked position.

    It seems to be a common problem (judging by the number of internet posts describing exactly your problem) with the iMac that that latch, after some usage, when depressed eventually fails to return to the 'up' position and remains instead sitting in the 'down' position, thus telling the computer every SD card you insert is locked, regardless of whether the card itself is locked or unlocked.

    Why am i making this guess? Because i (and you) have tried the same SD card on an external reader and, in that case, the computer reads the card as (correctly) unlocked. The iMac card reader perpetually reads it as locked.

    Solution? Apple may replace your card reader if your computer is still under warranty. Les-inconvenient solution: use an external card reader.


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