Help! I've cooked 4 DVD drives and now have 2 PSUs

Discussion in 'Mac Pro' started by jmdrawneek, Mar 29, 2012.

  1. jmdrawneek macrumors newbie

    Joined:
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    UK
    #1
    Hello,
    Anyone got any ideas to whats going on? I'm stumped.

    2008 8-core 2.8ghz Mac Pro

    The 2 old drives died ages ago and I have only just got round to replacing them.

    The system seems to run fine with nothing in the optical bays.

    When I connect a optical drive to the molex+sata (or pata) in the optical bay the Mac won't boot. And the OT (over temperature) LEDs light up on the logic board (Also the RAM LEDs all lit up simultaneously a couple of times but seem to have stopped). Shortly followed by the smell of burning plastic from the DVD drive.

    Thinking that the PSU must be on the blink I opened it to check for damage on the power rail effected. All seemed fine (no popped capacitors etc).

    Bought a new PSU, arrived yesterday. Doesn't exactly the same. :(


    Any ideas?


    Thanks.
     
  2. sOwL macrumors 6502

    sOwL

    Joined:
    Sep 25, 2007
    Location:
    Nerd Cave
    #2
    Have you reset PRAM and SMC? It's makes more sense to reset SMC first then PRAM.

    Resetting SMC: Take out the power source. Hold down the power button for anything more than approx. 10 seconds. Apple says 30 sec, but from experience I don't think you need all that much.

    Resetting PRAM: Boot your mac and hold down cmd(apple)+alt(option)+P+R. Keep holding them until it reboots.

    What exactly do you mean by not booting? Do you get a black screen?

    edit: I just picked up that part about the burning plastic smell. That sounds nasty... Is the drive new? Also could it be possible that you had some kind of power failure while it was installed?
     
  3. seer macrumors member

    Joined:
    Oct 3, 2007
    #3
    To follow on with the smell thing ... You sure that there is no metal garbage that is in the case that could be causing a short? My sister had similar symptoms and went I cracked open the case there was a house key lying on the motherboard! "ohhhh so thats where it went" she said :)

    Thought it was a one off, but then a couple of years later I was fixing a customer's computer that he had problems with and I found a paper clip that was magnetised and lying right across 12v rail!
     
  4. sOwL macrumors 6502

    sOwL

    Joined:
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    #4
    Haha funny you mention that.. I was fixing a customer's computer too one day that supposedly wouldn't even boot. The problem was that there was a plastic bag on the graphics card that prevented the fan from spinning. That plastic bag contained... illegal substances lol. So he was like "oh yeah thats where i've hidden it, right"
     
  5. AppleNewton macrumors 68000

    AppleNewton

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    #5
    I would try the very least replacing the IDE/ATA Cable or using a temporary one to see if that is the case.
    It could be the Molex power cable coming from the PSU that might be shorted or not plugged in all the way either.

    You dont happen to have any E-IDE/ATA drives to test in the optical bays?

    if you can power up the entire machine sans Optical Drive, then thats the area I'd focus on.
    If nothing else, worse case scenario it could be the connector on the Logic Board.
     
  6. jmdrawneek thread starter macrumors newbie

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    Mar 29, 2012
    Location:
    UK
    #6
    Meh

    Thanks for the replies guys!

    Can someone explain to me what the benefits of resetting the PRAM and SMC? I thought thats if your having power management issues (no waking from sleep etc?).


    I took the whole thing apart, including taking the logic board out. There doesn't seem to be anything lodged inside.

    I tried a E-IDE/ATA drive, that would be dead drive number 4.

    And it boots up and behaves fine with no drive attached.

    Could I get power from anywhere else in the machine to power some drives?


    Thanks.
     
  7. sOwL macrumors 6502

    sOwL

    Joined:
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    #7
    I'm not the best to explain this in detail, but let me just say that resetting SMC and PRAM are the first and basic troubleshooting steps. You'd be surprised at how many problems are solved that way. If we're not talking about actual hardware failure, that is. Usually PRAM is needed to be reset if you're having problems after changing hardware.

    I'm not sure about your MP but I'll give it a go: You should have 2 sata connections for your dvd drives on top, right? The logic board itself should have 2 PCIe connectors for the graphics cards. You could get power from there with the right cables. Also, you could hook up cables to one of your HD bays and connect it there.
     
  8. AppleNewton macrumors 68000

    AppleNewton

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    #8
    I meant actual hard disk drive and not another optical drive.
    Something you can put an OS on.

    There seems to be a short either through the Logic Board.


    I would not recommend using this as a method of supplying power for anything other then the PCIe or GPU cards.
    HDD bays are SATA, Optical is ATA
     
  9. jmdrawneek thread starter macrumors newbie

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  10. sOwL macrumors 6502

    sOwL

    Joined:
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    #10
    @AppleNewton:
    You can convert from SATA to ATA it's not a big deal I have done this on my machine and it works fine. About the PCIe, I think it would work, since the opposite (powering up a GPU from molex) is possible and I have also done this on my machine.

    @jmdrawneek:
    An "OS" is an Operating System :)
     

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