Power Up Problems with Power Mac G5

Discussion in 'PowerPC Macs' started by mrdarklight, May 9, 2011.

  1. mrdarklight macrumors newbie

    May 9, 2011
    I bought a Power Mac G5 online (Dual 2.3Ghz) and got it up and running with new peripherals. I installed OSX 10.4 on it, and it started up and ran fine. I adjusted the power saver settings at one point and that seems to be where the problem started. After I changed the sleep time, it never went to sleep after that. So one day I manually told it to sleep, and it did... and wouldn't turn back on. I click the reset button on the front and I hear a click, and a fan starts, the white light in front comes on and a red light inside comes on. That lasts for about 1 second, then another click and it all goes back off.

    I looked it up elsewhere and they suggested replacing the battery. I took the old battery out and tested it, and it seemed to be bad... the reading started out high on a voltmeter but quickly went down into the bad zone. So I put a new battery in and voila, it seemed to fix it.

    But I shut it down again, and again it won't boot. Same symptoms. It comes on for about 1 second and immediately goes back off.

    The weird part (well, one of them) is that I took the backup battery out and tried to boot it a few times, and it booted on the third try, with no battery present. So there goes my theory about the batteries. I tested the new battery I put in it and it exhibited the same test symptoms - the voltage slowly went down while connected to the tester. Then, I tested a brand new battery and apparently, all batteries exhibit that behavior - the reading starts out good but slowly goes down.

    So it looks like the batteries aren't bad at all, and anyway, it booted once with no battery at all.

    I'm beginning to suspect a power supply problem. Has anyone else seen this? Thanks.
  2. MHardee macrumors newbie

    Feb 18, 2008
  3. mrdarklight thread starter macrumors newbie

    May 9, 2011
    One other tidbit...

    I had another video card sitting around that I thought was compatible with this computer. Well, I installed it and it didn't work... but the computer did come on. It booted twice.

    One of two things is going on: The power supply is weak and it can handle the smaller (second) card better than the big (first) card with a fan, or... the computer will boot after it sits for a while... which I also understand is indicative of a bad PS.
  4. troutweed macrumors member

    Aug 3, 2010
    Hobart, Australia
    Try this.

    Unplug the machine. Open the side, remove the clear plastic cover, pull out the grey fan-housing (near the front) and press the small grey button at the bottom of the circuit board (to the right of the small flat battery and a lead coming up through the base).

    Try starting it.

    Fixed a similar problem on my old G5 at work!:D
  5. burnout8488 macrumors 6502a

    May 8, 2011
    Endwell, NY
    A similar thing happened to me last week. Started, boot chime, then off again with the red light inside.

    I fixed my problem using diskwarrior.... but that might not be your issue.

    Can you start the computer up in Verbose mode to see what the issue is on your screen? I believe you just hold "v" during startup.... maybe cmd-v.

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