Bizarre problem. pram? powersupply?

Discussion in 'Mac Pro' started by muzeum, Jan 1, 2008.

  1. muzeum macrumors newbie

    Joined:
    Jan 1, 2008
    #1
    here's my strange story of a misbehaving mac...
    it is a dual 1.42 G4 powermac

    When I shut my computer down, I cannot turn it on again by pressing the power button. No reaction. However, if I go to the power strip and quickly flip the power on/off there (while computer is off), then i can go to the computer and push the power button and it will turn on. It's as if it's heart stopped and i need to jolt it. "Clear!"

    So what gives? I was inclined to believe this was a PRAM problem because when i got the computer started date and time info were lost. But it is certainly possible i had damaged the powersupply... A year prior i replaced the fans of the powersupply for quieter fans. and because they move less air i put an additional fan on the back of the computer (behind the powersupply) to help evacuate the air and keep it cool. Well, i subletted an apartment with a cat and the cat had ripped out the power to the rear fan so i probably did get the powersupply very hot. And then the problem began. But arguing against the damaged powersupply theory is the fact that once it's on, it runs perfectly normal.

    Well, I'd be glad for any insight you might offer. thanks.

    M
     
  2. Eidorian macrumors Penryn

    Eidorian

    Joined:
    Mar 23, 2005
    Location:
    Indianapolis
  3. Makosuke macrumors 603

    Joined:
    Aug 15, 2001
    Location:
    The Cool Part of CA, USA
    #3
    I agree-that sounds exactly like a PRAM battery issue. Not that expensive to replace, so it'd be the first thing to try.

    If getting a new battery doesn't immediately fix it, you might try one other thing before assuming the power supply: Unplug it from the wall, push the power button (to drain everything internally), take out the PRAM battery, then let it sit for a few hours. Reassemble everything, push the motherboard reset button(s) once (I forget what setup that Mac has), and try it.

    I've seen G4 towers with behavior similar to what you describe (or just flat-out refusing to boot at all) that ended up being basically a funked-up PMU issue caused (somehow) by a blackout.
     
  4. Eidorian macrumors Penryn

    Eidorian

    Joined:
    Mar 23, 2005
    Location:
    Indianapolis
    #4
    Great post! I have to agree entirely.

    http://eshop.macsales.com/item/Newer Technology/BAA36VPRAM/

    Here's an easy way to get a PRAM battery online. Still, a local electronics shop should have one as well. I know that a local one was selling them for $2.99 Vs. $12.99 at Radio Shack.
     
  5. muzeum thread starter macrumors newbie

    Joined:
    Jan 1, 2008
    #5
    Thanks for reply to my thread. i'll try the advice as soon as i can get my hands on a new battery. I've never encountered the motherboard reset button but I'll look into it. (hopefully won't be necessary). It's the last of the G4 towers, dual 1.42 MDD model incase someone could direct me where to look.

    regards,
    M
     
  6. Eidorian macrumors Penryn

    Eidorian

    Joined:
    Mar 23, 2005
    Location:
    Indianapolis
    #6
    The reset button is located right next to the battery. ;)
     

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