G4 wont turn on

Discussion in 'PowerPC Macs' started by thrasher, Sep 16, 2010.

  1. macrumors newbie

    Hi, so a friend of mine bought a new computer cause his old G4 wouldn't turn on, and instead of throwing it out he gave it to me to see if i could fix. Anyway i plug it in and try to turn it on and the power light on the front lights up for a second and turns off and nothing else happens. I tried resetting the pmu but that didnt seem to do anything. Is this G4 a lost cause and should just get scrapped or should is there anything i can do to fix it?

    Any help would be greatly appreciated.

    Thanks you all in advance :D
  2. Moderator emeritus


    Did you try all the steps here? Resetting not only the PMU, but the SMC and the PRAM.
  3. macrumors newbie

    I don't have a keyboard for it and I don't know how to reset the rest of the stuff. The site you sent me says to reset those other things that I need a keyboard.
  4. Moderator emeritus


    You're going to need a keyboard ...
  5. macrumors newbie

    Will a regular windows keyboard work? And will it actually register on any keyboard if the tower won't turn on?
  6. macrumors 68040


    it should work with any keyboard , only thing is on a windows keyboard the option key and and apple key are swapped ,
    means the Mac option/alt key is where the window is and the command/Apple key is where your alt key sits i think thats about the things to remember
  7. macrumors newbie

    Ok I'll try that when I get home. It will still register that I'm hitting keys even with the tower off?
  8. macrumors 68040


    I assume it's a PowerMac?

    In that case, it's the PSU. Get a cheap ATX PSU and rewire two cables.

    (MDD requires a non-ATX PSU, but even those are available as cheap PC parts)

    Which one?
    Graphite? (PCI-Graphcis, AGP-Graphics, Gigabit Ethernet, Digital Audio)


    Mirrored Drive Doors (MDD):
  9. macrumors 6502a


    Souds like a PSU issue to me. Like Giuly says it depends what model you have what kind of powersupply you need.
  10. macrumors newbie

    It's the mirror drive door one
  11. macrumors 68020


    Before going and buying parts look for a button that looks like this (caution large pic, button highlighted by red circle) inside the the G4 (should be on the main board, the pic has it by the battery your model might not have it there.)

    Press that button, close everything up and press the power button to see if it works... otherwise use the link r.j.s posted and follow those steps, then consider buying a PSU if that doesn't work.
  12. macrumors newbie

    Thanks for your help everyone, i think im going to just scrap the whole system. Didnt plan on putting any money into it. Was hoping it was an easy fix.
  13. macrumors 68000


    Before scrapping, you should google quick PSU fixes. You can get a PSU that will work in the $5-15 range and it's a really simple fix...
  14. macrumors newbie

    G4 wont turn on

    I had the exact same problem.I had to constantly unplug from the wall then plug back in for the power button to work.So replaced the battery,disconnected the HD,video card and drives,NOTHING. I then purchased a refurbished PS with a year warranty and installed it,same thing,power button light was on when pressed then went right off again.The fan started spinning faster and LOUDER .

    Then after getting ready to trash it I decided to take out the dual processor board and reseat it.Guess what.... IT'S WORKING AGAIN !!!!!

    Every once in a while it will crash,guess when that happens,whenever I CLOSE THE SIDE PANEL of the case.

    I think this is a design flaw.Every time we close the case back up it needs to "Click " to lock.I've found that the logic board is jarred loose enough to make the system crash.

    When it crashes,I take a bamboo chop stick ( because it's softer than a screwdriver ) and press 4 times on the two exposed sides( all four corners ) of the logic board into the mother board.Once it reseats it starts right up with zero problems.If I close it hard it crashes but once logic board is reseated it starts right up again.

    I hope this helps

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