PowerMac G5 powersupply may be dead..help diagnose?

Discussion in 'PowerPC Macs' started by VideoBeagle, Jun 25, 2013.

  1. VideoBeagle macrumors 6502a

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    #1
    So the other night, while I was off in the kitchen getting dinner, my venerable power mac G5 desktop ...stopped.

    I came back, the monitors were in sleep so I moved the mouse, pressed space..nothing...so I concidered it might have crashed or something..held in the power to shut it down if on (I can't recall if fans were on or if i noticed). then went to press power and nothing happened. (there may have been a crackle sound..maybe not).

    Left it unplugged overnight, in case, maybe it over heated or something and shut down for that (been very hot), but still nothing. Tried different power cables..just in case, nothing).

    I've yanked the two drives and tested them, and they're both ok.

    I have instructions from iFixIt on how to remove the power supply.

    The problem is...i really don't know how to diagnose the problem beyond this.

    Any advice?

    (within the month, I'll be getting a new iMac, so things aren't critical, but if i can figure out the problem and fix it for cheap, I'd prefer that to just junking it).
     
  2. rabidz7 macrumors 65816

    rabidz7

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    #2
    When you turn the mac on do you hear the fans spin at all?
     
  3. VideoBeagle thread starter macrumors 6502a

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    #3
    nope. Currently when I press the power button absolutely nothing happens. No sound, no lights, no fans, which is why I'm thinking power supply, but this is an area outside my troubleshooting skills.
     
  4. Lil Chillbil macrumors 65816

    Lil Chillbil

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    #4
    Its the power supply, without a doubt 99% of the time its not the power button :rolleyes:
     
  5. rabidz7 macrumors 65816

    rabidz7

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    #5
    Where do you live? In Cincinnati there is computerDNA, a store, that fixes any mac.

    ----------

    What PowerMac is this? One dual core or two single core processors or two dual core processors or one single single core.
     
  6. Lil Chillbil macrumors 65816

    Lil Chillbil

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    #6
    Dual 2.0Ghz processor model


    read the sig :cool:
     
  7. rabidz7 macrumors 65816

    rabidz7

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    #7
    Powersupply is dead for sure. This mac has no LCS.
     
  8. VideoBeagle thread starter macrumors 6502a

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    #8
    What is LCS in this context?
     
  9. rabidz7 macrumors 65816

    rabidz7

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    #9
    The cooling system of a G5 which can leak, spilling toxic freezing liquid on the CPU daughter card, lobo, and PowerSupply.
     
  10. VideoBeagle thread starter macrumors 6502a

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    Ah.liguid cooling system!
    I knew "local comic store" didn't make sense!

    Thanks for the help...I'll report more after I pull the brick.
     
  11. honam1021 macrumors regular

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    #11
    When I first got my G5 it has the same problem with yours, I fixed it by resetting the PMU. You may also need to replace the PRAM battery, a dying battery is another common problem alongside faulty PSUs
     
  12. Member2010 macrumors regular

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    #12
    paper clip trick

    Back in high school, our teacher had somehow inherited one of these machines (this was actually what piqued my interest in the G5 in the first place) and it had been half taken apart in a plastic bin for years and we understood that it had always been a no power issue. We took the power supply out and the motherboard connector looked (to some degree) standard, so we tried the "paper clip trick" on the green and black connector while the power supply was out of the case - sure enough, no power. After buying a new Power supply, his computer was finally up and running again after all those years.

    If you have access to a paper clip, maybe this is worth a try?

    Paper clip trick demonstration

    ::
     
  13. VideoBeagle thread starter macrumors 6502a

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    #13
    got the Powersuplly out, but it's cables and pins bare no resemblence to the one in that tutorial, so I'll have to skip that step.

    I cleaned out a ton of dust bunnies from it...not sure if it's worth trying to hook it back up and see if it might start (just in case something of that was causing a problem). Meantime, I'm shopping for a new one.
     
  14. Andropov macrumors regular

    Andropov

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    #14
    Looks like is the power supply, but, just in case, bridge the PowerON wire with one ground and pug it into AC.

    I used this pinout to try:
    [​IMG]

    Although I think it's reversed, or I didn't understand it well the first time. Anyway, ground is black, PowerON is the only green wire. Bridge them with a clip and then plug it. Do not touch the clip or anything inside the PSU while connected.

    PS: Look if this is broken:
    [​IMG]

    It's near the four big reddish capacitors. If it's broken (looking like the photo above) and nothing else looks damaged, maybe you can find someone willing to try to replace the broken part (I bought it for 5$ shipped).

    Good luck!
     
  15. VideoBeagle, Jul 9, 2013
    Last edited: Jul 9, 2013

    VideoBeagle thread starter macrumors 6502a

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    #15
    Thanks.

    Tried that, no power.

    That component looks ok. I don't see any thing that looks broken.

    Using a multimeter, i can confirm the fuse is blown, or as best i can do without removing it. I don't think I can get the fuse out without pulling out the soldering iron.

    Gonna search for anything on how to do that.
     

    Attached Files:

  16. Member2010 macrumors regular

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    #16
    message

    Just find the main motherboard connector and short the green and black pins like this guy said:

    I'm pretty sure that touching the 5volt paperclip won't hurt you. Infact, I doubt you'd even feel it.

    ::
     
  17. MisterKeeks macrumors 68000

    MisterKeeks

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    #17
    Trust me, you don't toxic freezing liquid on your lobo.
     
  18. VideoBeagle thread starter macrumors 6502a

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    #18
    Continuing to research the power supply and fuse, but in the meantime, I was able to order a replacement from ebay for $25 (with a "Make an Offer" button).
     
  19. Andropov macrumors regular

    Andropov

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    #19
    Nice! Here in Spain, due to shipping, the cheapest PSU for the G5 I found was 75$ shipped, so I had to repair mine. :rolleyes:

    Another option is a PC ATX PSU. They're now more efficient and less than half the size. They're also new, so it's much less likely they'll fail in the short therm. You'd loose the Power LED light/ADC display though.
     
  20. VideoBeagle thread starter macrumors 6502a

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    #20
    Yeah, I read up on that process..the first one I found seemed way more complicated than I'm comfortable with.

    Had I not found this deal, I'd explore that option, and may if needed in the future
     
  21. VideoBeagle thread starter macrumors 6502a

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    #21
    Got the new power supply..installed it...re-assembled the mac...and everything is going!
     
  22. rabidz7 macrumors 65816

    rabidz7

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  23. Member2010 macrumors regular

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    #23
    calibration

    Did you have to run the thermal calibration disc?


    ::
     
  24. VideoBeagle thread starter macrumors 6502a

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    #24
    I'm going to say no...as I don't know what that is :confused:

    EDIT: a quick google later...I did put in a ASD disk, to see if there was a PRAM battery test on it to no avail, but I didn't see anything on thermal calibration (unless it ran automatically....I forgot to turn on the monitor ASD loaded on for a bit trying to figure out why I had a blank screen..doi!
     

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