iMac (intel) powering self off shortly after power on

Discussion in 'iMac' started by Maximzodal, Jan 16, 2010.

  1. Maximzodal macrumors newbie

    Joined:
    Jan 16, 2010
    Location:
    Houston
    #1
    2006 intel iMac, 4 gb RAM, OS X 10.6.2 Logic board and Superdrive replaced in May 2009 under applecare warranty.

    Upon turning on, turns itself off after times varying from 2-10 seconds. Sometimes requires unplugging power cord to turn on, sometimes doesn't. TechTools Pro ran once but the iMac powered off after starting RAM test. iMac powers off before TTP can even start now. I reset SMC and Pram to no avail. The varying it craps out makes me think a flaky power supply? From past experience the Apple store is going to tell me the repair cost isn't worth it, just buy a new iMac. Anyone have any ideas or suggestions?

    Thanks,
    Max
     
  2. SaSaSushi macrumors 68040

    SaSaSushi

    Joined:
    Aug 8, 2007
    Location:
    Takamatsu, Japan
    #2
    You should bring it in to the Apple Store and have them diagnose it to be sure. It sounds like it could be one of two things, the power supply gone bad or the logic board. If it is the logic board then it indeed wouldn't be worth the repair/replacement cost. If it is a bad PSU it would also be expensive (probably $200 to $250), but not as much as the price of a new Mac. ;)

    Good luck with it.
     
  3. archipellago macrumors 65816

    Joined:
    Aug 16, 2008
  4. Maximzodal thread starter macrumors newbie

    Joined:
    Jan 16, 2010
    Location:
    Houston
    #4
    Took it to the Computer Hospital yesterday and left it running iTunes so they could hear when it shut down. They just called to say after 26 hours it was still running and that a failing UPS could cause the spontaneous shut downs. Guess I will get a replacement. Anyone heard a failing UPS could cause this problem?

    max
    Houston
     
  5. urfish macrumors newbie

    Joined:
    Jan 18, 2010
    #5
    I've never heard of a UPS causing this, but that doesn't mean it can't happen. Especially if you're hooked to it for more than power (e.g. usb for application management or something crazy like that).

    I'm sure you've already done it, but check your console and see what the last messages you get are. Sounds simple but I had a narcoleptic G5 a few years ago that was reading an overheated CPU which caused it to sleep at inopportune times.

    If it is a cpu issue, it might just be a bad fan or a heatsink that's lost its paste for some reason. Of course, it might be worse, but this is a good place to start if you haven't yet gone there.

    Good luck!
     
  6. Maximzodal thread starter macrumors newbie

    Joined:
    Jan 16, 2010
    Location:
    Houston
    #6
    UPS Did The Trick

    The iMac has been running continuously for 2 days since I hooked it up to a new UPS. Since the macs are rarely unattended I don't use any of the bells and whistles to monitor the power and pc that come with the APC units. I use them strictly for power backup. If the power goes out, I turn things off manually after 5 or so minutes.

    Console wasn't much help trying to track down the problem in this instance.

    I would never have suspected a faulty UPS! I've learned something with this incident. I had 34 pcs in one facility on APC UPS' but never saw this problem in 7 years. Is this something specific to macs?

    Thanks for the input though.

    Max
     
  7. MacModMachine macrumors 68020

    MacModMachine

    Joined:
    Apr 3, 2009
    Location:
    Canada
    #7
    of course ups's can cause this

    they will fail and shut off the ups...even on the battery side.

    this can be caused by too much load also, devices will consume more power under load, so it will work fine until the ups is put under load and it will fail.

    this is very common, i see it all the time.
     

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