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Apple G4 Power Supply Woes?

Posted by Cliff on from the don't-taunt-happy-fun-power-supply dept.

Predius asks: "I, like many others based on forum hopping, have an Apple G4 desktop that has decided it no longer wishes to power up. I've replaced PRAM batteries, verified power supply voltages, pressed the CUDA switch, and done combinations of the above. Trying to start it just results in a blip of the powersupply fan and the power led on the motherboard flashes once. Every now and then it will actually boot, and when it does it's 100% rock solid, will reboot fine, etc. If I power it off, I get to play games again trying to power it up. Does anyone know how to manually start an Apple Gigabyte or later rev power supply? Standard ATX power supplies can be fired up by shorting the green PWR ON lead to ground, but Apple decided to be different. I await the collective's wisdom."

3 of 152 comments (clear)

  1. corrupt PMU? by Lizard_King · · Score: 5, Informative

    Have you tried resetting the PMU?

    Pop that sucker open (unplug first!) and there should be a little black button on the lower front of the logic board. "Reset pmu" will be printed on the board somewhere near the button. Push it for one second and only press it once. Let the box sit for roughly 5 minutes unplugged and then turn it on.

    --
    "My mother never saw the irony in calling me a son-of-a-bitch." - Jack Nicholson
  2. Aggravating problem by Mulligan · · Score: 5, Informative

    Especially if you are out of warranty. Apple describes it in support article 95039. The most frustrating part is that replacing the power supply is the last step -- they try to replace the CPU before checking the power supply. This means that you have to commit to purchasing a CPU if it is the problem child. My CPU (500Mhz G4) was ~USD900 last time I checked -- more than the value of the the computer at the time. All this is after you pay their diagnostic fee.

    Don't get me wrong, Apple Care is wonderful, but once it expires you can be in for some expensive repairs...

  3. Obvious? by YouHaveSnail · · Score: 5, Insightful

    I hate to ask the obvious, but since your machine is clearly working improperly in a manner that cannot be due to software, OS installation, disk formatting, etc....

    Have you considered taking it in for service?

    The friendly folks at the nearest Apple Store will be happy to take a look at it. If it's still under warrantee, or if you've invested in AppleCare, it won't even cost you anything.