14 Replies Latest reply: Jan 21, 2010 4:19 PM by spudnuty
LemonadeNZ Level 1 Level 1 (0 points)
2.1 GHz PowerPC G5, 1.5GB DDR2 SDRAM, OSX10.4.11

My mac keeps putting itself to sleep at random times. Often when I am in the middle of something.

Often (but not always) its when I am playing a game. I have to hit the return key and space bar to wake it back up again. Sometimes I am just surfing the net. Sometimes I am just typing.

I've turned sleep off altogether, and I've run the disk utilities stuff. And its still doing it.

Sometimes I can't get it to wake up, and have to shut down using the power button and starting up again.

I often get messages saying my computer is too slow for some games (***?)

Could it be overheating? Or is it the power supply? There seems to be a few people on here with problems similar to this. We had the power supply replaced about 18 months ago. Has anyone fixed this problem, and can report back definitively what it is?

What's happening? Is there something wrong with my computer, or do I need an upgrade?

Thanks

iMac G5 PPC, Mac OS X (10.4.11)
  • 1. Re: PPC G5 iMac keeps going to sleep at random times
    Kenichi Watanabe Level 7 Level 7 (30,030 points)
    If you have not already, reset PRAM

    http://support.apple.com/kb/HT1379

    and then reset SMU (power management)

    http://support.apple.com/kb/HT1767

    Be sure to follow the procedure precisely. When you reconnect to power, if you are using a crowded or old power strip (surge suppressor), try connecting it directly to the wall outlet, at least during this initial test. Power it up with nothing connected, except the power cord. After starting up, add only your keyboard/mouse. Use it that way for a while, and see if this problem recurs. If it does not, you can add your other peripheral (USB/FireWire) devices, one by one if possible. If the problem does recur at some point, note which device was added last. It may be faulty or somehow interfering with the iMac; USB and FireWire devices can effect the iMac's sleep, wake, shutdown, and startup.
  • 2. Re: PPC G5 iMac keeps going to sleep at random times
    LemonadeNZ Level 1 Level 1 (0 points)
    Ok. Have done what you suggested.

    It seems to do it mainly when a browser is open. And it does it more and more frequently as the day progresses (i.e. the longer the computer has been up).

    Thanks
  • 3. Re: PPC G5 iMac keeps going to sleep at random times
    LemonadeNZ Level 1 Level 1 (0 points)
    Sorry – I did edit the above to include the information:

    Its still doing it

    I only have the keyboard, Apple Airport and broadband router modem connected.

    Cheers
  • 4. Re: PPC G5 iMac keeps going to sleep at random times
    Kenichi Watanabe Level 7 Level 7 (30,030 points)
    If you have done the resets and the problem still recurs, even with only the basic stuff connected, it may be a hardware problem, such as power supply or logic board.

    The only other thing you can try (to rule out or confirm a software-related cause) is to start up from a fresh system installation, to see if the problem still recurs. If you have an external FireWire drive that you can erase, you can install a test system there and boot from it. Otherwise, you would have to back up your data (should probably do that now anyways if you have not already), erase the drive, and install a new system.

    If the problem still recurs while started up from a new installation, then it is very likely that the cause is hardware-related.
  • 5. Re: PPC G5 iMac keeps going to sleep at random times
    LemonadeNZ Level 1 Level 1 (0 points)
    Thanks. How do I determine whether its power supply or logic board? My understandings are that a power supply is relatively cheap to replace, whereas a new logic board, basically means a new computer!
  • 6. Re: PPC G5 iMac keeps going to sleep at random times
    Kenichi Watanabe Level 7 Level 7 (30,030 points)
    Once it gets down to likely being hardware-related, it become more difficult to determine the exact cause without a someone opening it up to investigate. If you determine it is definitely hardware-related, you may want to post another topic here with that question, someone here may know what to look for specifically, inside the case.

    One other test you could try (not as good as starting up from a fresh system) is to start up from your Mac OS X installation disc. When you get to the Installer screen, leave it there for a while. You can also do things like run Disk Utility from Installer's menu bar. Does this problem occur while started up from the installation disc?

    If it does, then that would pretty much show the cause to be hardware. If it does not, since you really can't stress the hardware too much while booted from the installation disc, it may still be hardware or software.
  • 7. Re: PPC G5 iMac keeps going to sleep at random times
    Michael Lafferty Level 6 Level 6 (16,080 points)
    The random sleep behavior and failure to wake from sleep are classic symptoms of a bad power supply. You can remove the back the visually check your logic board to see if there are visibly bloated, distended or leaking capacitors present in the various clusters on it, but you not likely to find any.

    If you remove your power supply, you'll find a polka-dot debris pattern on the underside of the chassis alongside the area where the top of the supply was mounted before you removed it. In most cases, a defective power supply will blow debris through the vented top case, staining the chassis.
  • 8. Re: PPC G5 iMac keeps going to sleep at random times
    LemonadeNZ Level 1 Level 1 (0 points)
    This will be the 2nd power supply this Mac has blown. Last one eighteen months ago.

    Surely, this must be a "known" problem that should be rectified at Apple's expense (and not ours?)
  • 9. Re: PPC G5 iMac keeps going to sleep at random times
    Michael Lafferty Level 6 Level 6 (16,080 points)
    If your power supply was previously replaced, then the polka dot pattern symptom is not a reliable indicator, as it already would have been present.

    Is it a known problem? Well, it does occur from time to time with a small number of iMac G5 power supplies. Apple offered a free exchange within three years of the date of first manufacture of a machine regardless of its warranty or AppleCare status. That repair extension authorization ended a year ago, and most machine eligibility by manufacturing data at least six months before that. They offered a 90 day parts and labor warranty on your replacement supply.

    While neither extended service offer covers your situatior, nor may either seem sufficient to you, they are as or more generous than coverage offered by other manufacturers under similar circumstances.
  • 10. Re: PPC G5 iMac keeps going to sleep at random times
    LemonadeNZ Level 1 Level 1 (0 points)
    Hi and thanks. If Apple offered a free exchange within three years of date of first manufacture, we certainly weren't offered it here (nor told about it) in New Zealand.

    I think we paid somewhere in the region of $350 NZ parts and labour. We'd only had the Mac for a couple of years till then.

    Anyway, I am still hoping, that at most, its just the power supply (and not the logic board, which I assume would mean a new computer altogether?)

    Thanks.
  • 11. Re: PPC G5 iMac keeps going to sleep at random times
    Michael Lafferty Level 6 Level 6 (16,080 points)
    Your options are somewhat limited, as the cost of shipping a machine for service to the US is likely quite prohibitive. Even if it is the power supply alone that you need, a price of typically $ 139.00 US plus shipping one way to your for a three pound package may not be attractive.

    You can remove the back to look for evidence that the logic board has defective capacitors on board. Send a message to the electronic mail address in my Public Profile and I will reply with a short diagnostic note and a picture of where to look…
  • 12. Re: PPC G5 iMac keeps going to sleep at random times
    spudnuty Level 5 Level 5 (5,250 points)
    Hey Lemon,
    Surely, this must be a "known" problem ..

    Well as Michael has said there was a recall that ended last year. However it did not involve the iSight model.
    This will be the 2nd power supply this Mac has blown
    ....that should be rectified at Apple's expense (and not ours?)

    Was there a warranty on this repair? Done by Apple? You could appeal to them. There are Apple reps and there are Apple reps, I've often gone through a few until I found one that would help.
    Here is the definitive site on bad caps:
    http://jimwarholic.com/2008/07/how-to-repair-apple-imac-g5.php
    For a .pdf specifically about the power supply, Google:
    "iMac G5 iSight ATX"
    The second item returned is the .pdf. It does mention the iSight models.
    Yours would be the last G5 iSight made and has a power supply quite different than the one referenced in Jim's site or pdf.
    I've run/am running the earlier models w/ an modded ATX and a 24V supply from an old Apple laptop.
    In many ways the iSight's easier to deal with since everything is plainly visible and not in a case. So if there are bad caps they would be plainly visible but sometimes they can fail and not be visibly bad. Only a check w/ an ESR meter would tell. On the other hand the iSight is weird since it seems like there's a main board and a sub board of some kind. So more research is required to reverse engineer an alternate solution.
    A quick search for an ATX solution to the iSight model only shows that a lot of people are looking for it and appeals for someone to develop a scheme. I have a 20" iSight taken apart here on my bench but it supposedly had a good PS. I picked it up for $50 and am waiting for the seller to find the RAM for it (From a unscrupulous dealer who told him the logic board was bad even tho' it booted from a CD installer. Wanted him to pay $700 for the repair or whatever for a new one) Once I have the RAM I can power it up and test it so I'm want to try an ATX solution on it.
    Richard

    Message was edited by: spudnuty
  • 13. Re: PPC G5 iMac keeps going to sleep at random times
    Felipe Rodrigues Level 1 Level 1 (15 points)
    Same thing happening to my G5 ISight. I was just informed that the power supply will have to be replaced for a cost of R$ 530, or ~US$ 350 in parts and service.
    It´s a shame that Apple does not send email's to owners informing of the recall. I specifically remeber registering the product online.
    US$ 350 dollars on an old computer? I´m really having second thoughts here.
  • 14. Re: PPC G5 iMac keeps going to sleep at random times
    spudnuty Level 5 Level 5 (5,250 points)
    Hey Filipe and Welcome to Apple Discussions,
    Wow US $350 that's a lot. Where are you located? If it is the power supply it's actually relatively easy to switch. It's only getting to it in the iSight model that's a pain.
    Can you get the power supply directly?
    What were the symptoms of your failure.
    Richard