iMac self shutdown

Discussion in 'iMac' started by montysala, Sep 5, 2016.

  1. montysala macrumors newbie

    Sep 5, 2016
    So I have searched for an answer to the iMac self shutdown and all the threads I have seen have given no answers. My early 2009 24" imac started shutting off on it's own a few months ago and it progressively got worse until now I will not last more than 5 mins. I replaced the power supply which did nothing. I replaced the logic board which did nothing. I replaced the hard drive which did nothing. So now I am at a loss. If it isn't one of those 3 then it must be something small and stupid but I can't figure it out and the 'genius bar' is no help either. Obviously no warranty but I am not afraid to fix it myself if I just knew what to fix. Any help would be appreciated.
  2. DeltaMac macrumors G3


    Jul 30, 2003
    Do you find any help by reviewing your logs in the Console? Log may show a shutdown reason.
    Next time you get shutdown, restart, then check in log for the approximate time of the shutdown.
    (random stuff...)
    Have you verified that all 3 fans are working? You can do that with the various apps that allow you to monitor fan speed and temps.
    Are all cooling air paths clean and clear? One that is often missed is the small round intake port on the back above the power cord connector.

    Is the hard drive original (more than 7 years old)? (I see you replaced the HDD, so good... )

    Be sure to try plugging the power cord into a different power strip, or directly into the wall, just as a test.
    Everything else has no change, and no fix - try replacing the DC power cable.

    I was working on a similar age iMac a few months ago with almost the same problem.
    Turned out to be the power supply, but I had to replace the power supply twice. The supplier that I use got in a batch of used power supplies from another company who claimed to have tested the used parts - but apparently missed a few.
    YOUR problem might still be a bad power supply, too. Think about it...
  3. tag macrumors 6502a


    Apr 29, 2005
    I'd also try plugging the iMac into a different outlet (on a different circuit). Maybe it's an issue with the electrical wiring not supplying enough power?
  4. montysala thread starter macrumors newbie

    Sep 5, 2016
    The problem was reproducible at the apple store and they ran the hardware test which showed no problems. They suggested either power supply or software which I have both replaced without success. Because the shutoff occurred with apple store power and their cord I could rule out those potential problems. When I replaced the power supply the iMac shuts off in the exact same manner as the previous power supply. It would be extremely bad luck if both were exactly bad but I guess it is possible. Does anyone think there could be a RAM problem? I have the original RAM but I'm not sure if RAM has that kind of power.
  5. TheBigDog macrumors member


    Sep 5, 2016
    London, United Kingdom
    How can you expect the 'Genius Bar' to support a vintage machine, which you've also modified.

    Maybe it's time to call 7 years a good innings. :)
  6. rshrugged, Sep 5, 2016
    Last edited: Sep 5, 2016

    rshrugged macrumors 6502a

    Oct 11, 2015
    As part of your troubleshooting (and as a plan B), create a bootable clone on an external drive to see if the behavior is repeated there.

    Edit : another troubleshooting thought occurred to me. Turn your brightness down to the lowest possible level to where you're still able to see screen content. See if you get additional time before the machine shuts down.

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