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  • BellaMichelle Level 2 (205 points)
    Rod, is the power supply something relatively easy to replace if I buy one?

    my iMac has begun to 'shut off' for no apparent reason.. no freezing, it just shuts down. I see from this thread that it is an issue.. and I posted that I already had my power supply replaced and, I think, my logic board in Aug of 06. At that time, it stopped starting up.. a gray screen. This time it is shutting down for no reason. I found my receipt from the first repair and it says they replaced 661-3350 and 661-3599.. the first is a power supply, but I don't know for sure what the second part it.. but it says board, logic next to it. I did a search at synaptech and see the power supply, but not the logic board.

    thanks for any help.. I don't really want to buy a new computer if I don't have to.. though they are gorgeous.. and I'd probably buy a lap top this time and get a big monitor for desk use..but financially, I'd like to make this one keep working.

  • Rod Hagen Level 7 (31,985 points)
    Hi unique alias, and welcome to the forums

    Unless you are suffering from the very simple to fix problem of a badly seating power cord (which has the same effect) I think you can be almost certain that you have a bad power supply. Your symptoms are certainly almost a "classic case" of the problem, I'm afraid.

  • craigblackburn Level 1 (0 points)
    Hi Neil,
    I've had the iMac 24" 2.8Ghz for just over a year and until yesterday everything was perfect. I now have the same problem everyone else in this post is having. The random shutdown thing just started happening yesterday and it's driving me crazy. So it doesn't seem to be an issue specific to old iMacs - it's still happening. Good luck.
  • christing Level 1 (0 points)
    I have the same problem. My imacG5 1st gen died december 30. I have to change the logic card, 750 euros (I'm in France). Do you think it's normal??? Why dis I buy an expe,sive computer 3 years ago, thinking it's a strong and good machine ? It worked only 3 years... Why doesn't Apple nderstand that this kind of problem is unacceptable ???

    Sorry for my broken english !
  • Neil Reeves Level 1 (15 points)
    Hi Graig,
    Thanks for that info. Have you tried blowing the insides out with a tin of compressed air (remove the back to get to the fans) as this maybe thermal cutout due to dust. Loads came out of mine and ran much cooler before it failed.
    It's worth a try before an expensive trip to the repairers.
    Regards. Neil.

    Anyone else out there had problems with 24" 2.8GHz iMac?
  • BellaMichelle Level 2 (205 points)
    I have opened the back of my 1st gen imac and my capacitors all look good. I read that I should vacuum vents and use compressed air but I really am not clear on where to vacuum and where to blow. Can you tell me?

    thank you
  • MGW Level 7 (27,025 points)
    Michelle, you can vacuum the three fans that you see when you open your computer, and also the air vents in the back/bezel/case.

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  • BellaMichelle Level 2 (205 points)
    Thanks for the reply. I was hoping there was link with photos like there is for the capacitors, etc. I just did not want to miss any spots that are big dust caverns.

    All my capcitors are fine, no bulging or leaking so I did the big vacuum and compress air and will see what happens. I did have the green led light when I plugged it in so who knows what will happen.

    Some posts have referenced the temps, etc. What SHOULD the temps be? I have istat in my widgets and would love to know what things to watch for there, to help me solve the isse of my iMac shutting down.

    thanks for the help.
  • Judith Anne Level 1 (0 points)
    Just FYI, for all of you with this shutdown problem. I had the same problem and decided, with the help of so many of the nice folks who share their expertise here on these boards, to try simply replacing the power supply (as the less expensive option, hoping that would do it--vs either a trip to Apple store--quite a distance from where I live--or replacing logic board). Purchased one online for considerably less than the Apple price (turned out to be exactly the same genuine Apple part), put it in (quite an easy repair if you are at all handy), and it has solved the problem 100%. No problems whatsoever since the replacement. For reference, thread entitled "Topic : random involuntary shudtowns/possible fan problem?"--last post was Dec. 22nd. Got the part from DV Warehouse, for about $125 including shipping. As I said, no problems at all since. Also, previous regular-though-not-very-frequent kernel panics have stopped as well, so those were most likely also a symptom of the gradually failing power supply. I'm annoyed that Apple wouldn't cover it since my computer was 4 years old--I understand they have to set some limits, but if they KNOW they have a bad part, I can't quite accept that an arbitrary cutoff date for replacement is really legit--especially considering all the free advertising and promotion I'd previously done for them as a real Apple lover. I'm a bit more circumspect now with regard to that. The whole thing has made it clear to me one is only a truly valued customer to Apple if regularly and frequently purchasing a brand-new machine. They aren't too concerned about you if you are making the "older" one last, in spite of still doing some bragging about backward-compatibility. Be advised that if you don't purchase new machines often enough, you are pretty much no longer on their radar screen. In spite of that, for now, I'll still use a mac. But I'm much much more cautious and skeptical than I was before this experience.

  • BellaMichelle Level 2 (205 points)
    Hi Judy,

    I've checked my logic board and all my capacitors are fine, no bulging or leaking so it may be my power supply. I vacuumed it out thoroughly and used compressed air as well. So for now, I am going to wait and watch. If it continues to do this, I may just change out the power supply. Your email said it was an easy repair. Did you follow any specific directions? If so, will you share them? I've read the power supply can be very dangerous. I know there is a link for Jim Warholic but the picture was complex and I felt overwhelmed by the article. So I am hoping, if it comes to that for me, that you can share some easy direction.

  • Denis Giguere Level 1 (5 points)

    I experience the same problem running OS 10.4.11

  • Judith Anne Level 1 (0 points)
    Michelle, I'd be happy to help. Here is a copy (slightly amended to clarify a couple of things) of what I posted in that other thread, after replacing mine:

    It's very easy to replace the power supply. Unplug all the peripherals and the computer. Put the computer face down on a towel. Unscrew the three screws along the bottom edge of the machine that hold the back on (they are captive screws--won't come out all the way). Lift the back off and set aside. Unplug the old power supply from the receptacle on the logic board (it might resist a bit; be gentle so as not to damage any surrounding parts). Unscrew three screws holding the power supply in (one, upper left, is captive; two others come out--don't lose them). BE CAREFUL taking it out--pull up the left end (to clear the capacitor thingy on the logic board right above the top of the left end of the power supply), THEN twist top of the power supply toward yourself to clear the screw bracket (on the computer base), and remove it. Watch it putting the new one in, too. It would be very easy to break that capacitor and then, I understand, you'd need a new logic board. The cost of which makes the $128 for the power supply seem quite cheap. Put the screws back, plug in the power supply, replace the back cover, turn those screws in, and plug everything back in. Quicker than typing this paragraph (I'm a slow typist.)

    I didn't follow any written directions; Apple apparently no longer considers this a user-doable repair, and so they have removed their directions. I assume this is due to the potential danger of damaging that one capacitor on the logic board when you remove/replace the power supply, though that is only an assumption, I couldn't find out why for certain.

    This really is simpler than it sounds. I don't know the Jim Warholic reference but if you post it I'll look at it to compare; maybe I can help clarify that one for you. If any of the description isn't clear, let me know (should you find you are going to do the repair). Aside from that one caution about the capacitor, which isn't too hard to accommodate, it really is just removing and replacing a few screws, unplugging old unit & plugging in new one.

    If you are seriously timid about it, you may want to just have Apple do it for you; I've seen references (here or on an earlier thread; don't recall which) that people have gotten it done by Apple for about $170. For me, that would have been a bigger hassle/expense, since it's almost a two-hour drive to the nearest Apple store, which would mean two round-trips (or shipping costs), plus being without the machine entirely for who-knows-how-long. Thought I would rather try the power supply repair on my own. Happily, for me that's all it was...

  • BellaMichelle Level 2 (205 points)
    Hi Judy, this does sound easy. I read somewhere that there you have to be careful touching or taking the power supply as you can either get hurt from the electrical charge or blow the power supply. Hence, my desire for a good how to.

    this is the link to the Jim Warholic reference

    let me know what you think.

  • Judith Anne Level 1 (0 points)
    OK, Michelle, I think the intimidation factor from that link is huge, but so far as I can tell, it's all about repairing the power supply, not simply replacing it. The photos he's showing and all the cautions, I think, are about opening up the power supply case and repairing it by replacing capacitors inside. It's probably a much cheaper repair for people who know what they are doing, but I would not attempt it myself at this point. But you don't deal with any of that if you are simply replacing the whole power supply unit. That's what the directions I gave are for. I am no hardware expert, so any additional clarification or comments from those who are would be welcomed. But you should have very little trouble just replacing the supply. All this I am basing on it being the iMac G5 without iSight--I'm told that one is not user-doable. You might want to read the thread I mentioned above here on this board. Also check -0353-----NEW-p-25613.html
    to see what the power supply looks like (this link is for the one that's right for my computer; you'll need to make sure you order the correct one for can email customer service at DV Warehouse with the serial numbers from your computer and they can tell you for sure).
    Hope this helps.

  • Craigwd_2000 Level 4 (1,300 points)
    My Rev A '17 iMac G5 1.8 GHz with Super Drive with 2 GBs of RAM also experienced the high speed fans issue too but only when booting into Single User Mode while running AppleJack 1.4.4 so maybe the high speed fan issue was related to having two bad logic boards in a row but I can't say for sure. We're going to try removing the logic board from my iMac G5 manually (even though the Service Manual doesn't even tell you how to do it...) & send it in to for recapping which should be much cheaper than paying Apple $400 for a new logic board; the Super Drive is currently in my '12 PowerBook G4 1.5 GHz with 1.25 GBs of RAM & I plan to install a Nec OptiArc AD-7630-A which can burn every format including +R DL & -R DL except for Blue Ray.

    Liggy & Dee of even have RPC1 firmware with a PowerPC Mac flashing application available for the drive too which is another reason to get it instead of other slot loading DVD Burners that require a PC/Windows for flashing firmware too.