Bad power supply?

Discussion in 'Mac Pro' started by heisenburg, Feb 26, 2013.

  1. macrumors newbie

    Aug 31, 2012
    My 2008 Mac Pro refuses to power on, when I push the power button nothing happens.No lights or fans power on; it acts like it is unplugged, but it is not unplugged. I tested the power cord in an another machine, and it worked fine. At this point, I'm thinking I will need to replace the power supply. Has anyone else had this issue?
  2. macrumors 65816


    Sep 6, 2009
    Try using a different power cord or plugging your Mac Pro to a different outlet. If nothing happens it may be likely your power supply. Is your Mac Pro plugged to a UPS with surge protector or plugged directly to the wall outlet when you are using this?
  3. macrumors 6502

    Sep 19, 2012
    Try unplugging EVERYTHING from the machine (all USB, monitors, ethernet, etc.) then plug power cord directly into a tested & working outlet. If the machine doesn't power on at that point, then it's probably the PSU. Can try unseating all PCI cards as well, but that's only caused a power issue for me once on a PC many years ago.

    If replacing PSU yourself, be sure to get the right part number, they're all a little different...
  4. thread starter macrumors newbie

    Aug 31, 2012
    I just removed the power supply from my Mac Pro. I then opened the power supply (yes I know there are 450v capacitors). I then tested the fuse which was not blown. I noticed that there was scorch marks on the metal inside the power supply. Does this just happen over time from high temperatures, or did my power supply have a melt down?
  5. macrumors 604

    Nov 17, 2008
    Hollywood, CA
    Make sure you do a SMC reset. Just means yanking the plug and then holding power button down for 5 seconds or so. Plug in again and hit power. Listen for click
  6. thread starter macrumors newbie

    Aug 31, 2012
    I see burn marks inside the power supply, so I assume, the power supply died. Do I have to get the exact same part number? The part number on my power supply happens to be the most expensive Mac Pro power supply there is. I see other Mac Pro power supplies with the same wattage and same power connectors, but they have a different part number. Will they be ok for me to use?
  7. macrumors 68040


    Dec 7, 2009
    You need 661-4677 (614-0409). These with different part numbers have different (lower) amperage on 12V lines. There is used one for $140 on US eBay ATM.

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