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Thread: iMac 24" Alu won't play...

  1. #1
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    Default iMac 24" Alu won't play...

    Bit of a weird one... boots up with the chime and then stops dead. No drive activity, nothing on the video but most weird is that there is no response from the keyboard input. I.e no PRAM reset, no target mode.
    It's beginning to feel like a graphics card AGAIN!
    Have I REALLY got to take out the card to see if it will boot headless? Or is there something else that I can do first?
    And, yes, I have taken out the ram, hard drive and all of the other things that you would EXPECT me to do.
    It doesn't help not having a manual for this one as I don't know what the fourth LED is supposed to be indicating - I know what the others are... I think.
    1 = Power detected
    2 = Power to video
    3 = Connection made to video
    4 = ?

  2. #2
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    I have also done an SMC reset, plugged in an external monitor, taken off the airport card etc etc.
    Looks like next step is graphics card out...

  3. #3
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    .....And tried to boot to an external drive (with a new enough OS to be sure it is compatible)?

    if 10.7, will it boot to the recovery partition?
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  4. #4
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    No chance of it booting off anything. But, for the record, I've had 10.6 and 10.7 drives attached. Doesn't get as far as engaging the drive, no matter what it is.
    Having taken out the graphics card as well I have to conclude that the logic board is dead. What is puzzling me is that it gets the startup chime. I take the ram out and it beeps as expected, so it's getting through the POST and then giving up. Most strange.

  5. #5
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    That aluminum iMac... is it too new to have the capacitor problem? Look at all the caps and see if any are bulging/leaking.
    Damien,

  6. #6
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    Hmm, put it all back together again now!
    Are you talking about caps on the logic board?
    It's an early 2008 24" 3.06ghz.

  7. #7
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    Yeah, way too new to be part of the (now old) caps issue.

    Still behaving the same, after reassembly?
    "Imagine if every Thursday your shoes exploded if you tied them the usual way. This happens to us all the time with computers, and nobody thinks of complaining." -- Jef Raskin

  8. #8
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    Yes, no difference at all. I've done everything that I can so it has to be a logic board failure. I can't find any replacements online anywhere so I suspect that I'll break it up for spares and he'll buy a new one.
    The graphics card should fetch a decent price.

  9. #9
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    Can't be anything but logic board so it's gone off to Apple for a new one.

  10. #10
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    sounds like the GPU has gone in that imac

  11. #11
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    If it had been the graphics card it would have booted headless when I took it out.

  12. #12
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    Not all macs will boot headless, but I don't know if that one will or not.
    Damien,

  13. #13
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    Yes, that's an interesting point. However, I don't think that I've come across any Mac that is completely unresponsive to USB instructions (it needs USB to invoke target mode as well) where a defective logic board is not involved.
    With no video card installed, I would still have expected it to be able to do a PRAM reset even if it wouldn't go any further. It wouldn't do that with or without the video card installed.
    I suppose I'll find out more when it's been to Apple for further diagnosis and, probably, repair.

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