12 Replies Latest reply: Jul 17, 2012 10:30 PM by BDAqua
mmurphy336 Level 1 Level 1 (0 points)

I have a G5 tower that is 7 years old. We recently moved and when I went to hook it up at our new house there are problems. At first the fans would just run and nothing would happen on the screen. After turning it off for awhile and turning it on later it finally would boot up but then quit after a minute or two. The power light on the front and on the monitor stays on but the just seems to quit. The fans stop. I can press the power button on the front and it will come on briefly but then quits again. I'm at a loss for what is wrong. Any suggestions?


G5 Tower, Mac OS X (10.6.6), Not sure about OS Version
  • 1. Re: Can someone help with a power issue with a G5 Tower?
    old comm guy Level 4 Level 4 (2,230 points)

    mmurphy336 wrote:

     

    I have a G5 tower that is 7 years old. We recently moved and when I went to hook it up at our new house there are problems.

     

    Well, the first two sentences raise the dead PRAM battery red flag.  If the battery has not been replaced for a couple of years, you probably should get a fresh one in.  The battery is either the 1/2-AA 3.6 volt Lithium located up in the PCI card area

     

    PRAM Bat Early 2005.png

     

    or (for the late 2005 machines) the 2032 coin cell located down in the RAM area.

     

    PRAM Batt Late 2005.png

     

    In any event, you might try an SMU reset on the machine, but be advised that with a weak or dead PRAM battery, this can be quite futile.  Weak or dead PRAM batteries can cause all sorts of startup mischief, as they allow garbage data to be read from PRAM and also can foul the SMU which is what is the initial controller for startup.

  • 2. Re: Can someone help with a power issue with a G5 Tower?
    BDAqua Level 10 Level 10 (116,470 points)

    Very nicely done!

  • 3. Re: Can someone help with a power issue with a G5 Tower?
    old comm guy Level 4 Level 4 (2,230 points)

    BDAqua wrote:

     

    Very nicely done!

     

    Thanks, BD.  I thought that clipping the art from the user manuals would help...might as well make use of that good Apple illustration base. 

     

    Too bad that the most readily available 1/2-AA cells at the retail store level are so darned expensive. 

     

    Fry's here in Southern Cal has quit carrying the Saft batteries, and as I noted in another post, the shipping was unreal for the ones I bought from Minnesota.  On the other hand, I now have the equivalent of $100 of the store batteries sitting in readiness (or $30 at the last Fry's price), with the long shelf life of Lithium being a positive aspect.

  • 4. Re: Can someone help with a power issue with a G5 Tower?
    mmurphy336 Level 1 Level 1 (0 points)

    Thanks so much for the advice and the illustrations. It was very helpful. My G5 was one of the early ones with 1/2-AA 3.6 volt Lithium. When I went to get it out the bottom tab broke, so I hope when I get a new one to stick back in there will be enough tension on the battey to hold it in place. I just check my local Radio Shack online and they are supposed to have Saft LS14250 3.6V/1200mAh Lithium as a replacement. I'll get it tomorrow and let you know if that fixed the problem. Rather it fixes it or not I really appreciate your timely advice. What a great resource you and the Apple Support Community are.

  • 5. Re: Can someone help with a power issue with a G5 Tower?
    mmurphy336 Level 1 Level 1 (0 points)

    Ok I replaced the battery and it starts up and gives a message that the computer's date is before 2001 or something and then shuts off. I tried to go tp the control panel and get the date corrected by it quits before I have a chance.

  • 6. Re: Can someone help with a power issue with a G5 Tower?
    old comm guy Level 4 Level 4 (2,230 points)

    OK, that it comes up enough to give you the message is encouraging.  When it shuts off, is it just clicking off, as opposed to a normal shutdown process?

     

    The next two things to try would be a PRAM reset, then a safe boot. 

     

    Reset PRAM by holding down the cmd-option-P-R keys when powering up until you hear the second boot tone (chime).  Safe boot by powering with the shift key held down.  Safe boot loads only those system extensions that are absolutely necessary, plus as a bonus, it attempts to repair minor directory errors in the boot volume.  (I'm now including this boilerplate paragraph for the benefit of other readers of this thread.)

     

    Added Info:  After a battery change or SMU reset, the computer's real-time clock is reset to zero, which corresponds to Midnight, January 1, 1970 GMT or UTC.  During the system startup process, the system attempts to find a time server to reset the real-time clock value.  If it can't, then it throws a message saying that the clock is set too early, probably meaning before the build date of the computer, but I am just guessing there.  For the moment, we don't need to worry about that until we can get the machine to stay up for more than a few seconds.

  • 7. Re: Can someone help with a power issue with a G5 Tower?
    mmurphy336 Level 1 Level 1 (0 points)

    I may have bad news. When tring to reset the PRAM I never get a second chime. Machine never boots up. Also to your first question - when it shut off after displaying the date message for a few seconds there was just a click off - no shutdown. I'm getting the feeling that we may have a bigger problem. Tried the safe boot with no luck. As a matter of fact the first chime seems to be cut off when trying the PRAM reset. Hope you have another something to try.

  • 8. Re: Can someone help with a power issue with a G5 Tower?
    old comm guy Level 4 Level 4 (2,230 points)

    Well, it appears that we are dealing with either SMU or power supply issues.  Since this machine has been sucking in cooling air for about seven years now, it is not unreasonable to expect that a lot of crud has lodged in the power supply. 

     

    There was a thread a year or so ago where the OP linked to some snaps of what his power supply looked like when he pulled it out to blow out the dust  (that link doesn't work any more, though).  His pictures were along the same lines of what I found when I pulled out my supply and blew out the dust.  A couple of problems that the impacted dust raises include incorrect voltage sense readings causing the supply to slam itself down (which is what my supply was doing when the video card was fully enabled) and also insufficient heat dissipation.

     

    That being said, you might want to, as a first try, attempt to blow dust out of the power supply using canned air.  This is not very effective, but sticking the nozzle in through the front grill at the rear just where the grill starts its curve and give it a few good shots.  Do this in several places.  Then repeat from the front, then do the back and front one more time each, then see if that helps.  If you are actually a little more adventuresome, you should remove the power supply (a somewhat involved process, with information on the ifixit.com website) and blow it out with shop air, or optimally, remove the top cover and blow it out.

  • 9. Re: Can someone help with a power issue with a G5 Tower?
    mmurphy336 Level 1 Level 1 (0 points)

    Looks like I've hit the wall. I tried blowing it out like you suggested but that didn't seem to help. I looked at the site you referenced on removing the power supply and decided I don't feel confortable tackling that. It never boots up now. I got it to chime twice only once resetting the PRAM. Once it came up with the Apple logo but never went passed that. Tried a safe boot. Nothing. Previously I had loaded a CD 1 from the old install set and now can't get it out. Pretty frustrating. I'm located in West KY. Know of any place I might be able to take it for repair?

  • 11. Re: Can someone help with a power issue with a G5 Tower?
    mmurphy336 Level 1 Level 1 (0 points)

    Tried the hair dryer trick. Still no luck. Thanks for all the advice from everyone, but it looks like it's a lost cause.

  • 12. Re: Can someone help with a power issue with a G5 Tower?
    BDAqua Level 10 Level 10 (116,470 points)

    Sniff, sniff, sorry to hear.