iMac G5 won't stay on; maybe a short?

Discussion in 'PowerPC Macs' started by gwuMACaddict, Jan 2, 2008.

  1. macrumors 68040


    Apr 21, 2003
    washington dc
    The computer boots sometimes, othertimes not at all. When it does turn on it stays on for an unreliable ammount of time before shutting off.

    Maybe a short?

    ANybody ever take the case off and blow air over the inside to clear out dust?

    Thanks for any advice...
  2. dcv
    macrumors G3

    May 24, 2005
    Could be indicative of a power supply and/or logic board failure.

    Which model do you have? If you have a Rev A (1.6/1.8 GHz G5) or a 20" Rev B (2.0GHz G5) then you should be covered by the repair extension programme, if indeed this is the case.

    Check here for rev A and here for rev B

    Otherwise... it might be worth just trying to reset the SMU to see if that makes any difference.
  3. macrumors 68000


    Feb 17, 2006
    Keele, United Kingdom
    Take the back case off and see if theres any dust in there too, if so get some compressed air and use that to blow it out. Then do what dcv said :cool:
  4. macrumors member

    Dec 14, 2007
    Is this an iMac G5 with an isight (camera on the front top center)? Is this an iMac G5 with an ambient light sensor? Look on the bottom and there will be a little thing that looks like a LED next to the center screw if it is an ambient light?

    With all that said. If you don't have an iMac G5 w/ iSight sounds like a classic REA issue to me. Couple ways you can check this.

    Lay the mac face down on a towel or something soft
    Unscrew the 3 screws on the bottom of the iMac (note: they won't come all the way out just loosen em)
    Lift up on the foot of the imac way from you and the back should pop off.
    Smell the power supply and see if it smells really awful if it does you got a bad PS.
    Also look at the capictors on the MLB they look like little metal capsules. Check to make sure they are all flat! None of them should be bulging or oozing any orange stuff. If they are you got a bad MLB. If either of these issues are present there is a REA for this issue and Apple will fix it for free so take it to the apple store.

    Boot up your mac.
    Open up utillities.
    Open up console.
    Click on system.log
    Search shut down, search temp, search thermal...see if you get anything there?

    Let me know what you find?
  5. thread starter macrumors 68040


    Apr 21, 2003
    washington dc
    You guys rock....

    Thanks for all the advice- will check serial numbers tonight to see if it might be the Power Supply.

    Will update once I know more.

  6. macrumors newbie

    Feb 10, 2012
    Still a problem for some of us....

    So I found this thread, having same issue. I have iMac G5 20" 2.0G (RevB) with intermittent shutdowns. In console system.log I found corresponding messages about "ThermalProfile - entry", "ThermalProfile - calling adjust", and "shutdown cause = -122" or "shutdown cause = -110". So what does that all mean?

    I haven't opened it up to check PS or capacitors yet, but when I bought the thing a year ago the prev. owner had done capacitor replacement.

  7. macrumors 68000

    tom vilsack

    Nov 20, 2010
    ladner cdn
    Im betting reseating ram or a stick of ram has gone bad...
  8. macrumors 6502

    Nov 26, 2010
    Possibly a fan is dyeing? Or the thermal paste on the CPU needs re-doing? Its a smaller chip so would be a pain, but it should be do-able

    Try and find the service manual for the G5, might be able to give some more clues on those error codes :)
  9. macrumors newbie

    Feb 10, 2012
    The system profiler says the RAM is ok.

    I will look for a service manual. That sounds like a good idea and an interesting project. :cool:

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