Causes of flashing light? (Powermac G5)

Discussion in 'PowerPC Macs' started by Projekt, Jun 7, 2012.

  1. Projekt macrumors member

    Joined:
    Apr 3, 2010
    #1
    I'm stumped: a powermac G5 with a known-good logic board/processor and a known-good video card refuses to start. Fans run, hard drive spins up, but the front light flashes continuously. Could it be the power supply?

    Any help would be greatly appreciated. I feel like I might be missing some small thing? This machine was assembled from scratch so I'm hoping I just didn't plug something in correctly.
     
  2. Rodus macrumors 6502a

    Rodus

    Joined:
    Oct 25, 2008
    Location:
    Midlands, UK
    #2
    Try a different RAM stick. Also, have you tried booting from an install disk?
     
  3. Projekt thread starter macrumors member

    Joined:
    Apr 3, 2010
    #3
    I don't think it is RAM- it is my understanding that RAM issues flash the light in increments of 3. I have tried several with no luck.

    I could swap hard drives, but the issue seems to be no video- even if I didn't have a drive in at all, I would see a grey screen with a question mark right?
     
  4. drorpheus macrumors regular

    Joined:
    Nov 20, 2010
    #4
    its not the powersupply, if it was it wouldn't start up at all. Sounds like either the processor is not properly seated, or there's damage to the logic board somewhere, like a scraped broken trace, take the cpu off and look over the pins on the logic board to see if there bent, move around at different angles and see if one or any of the pins casts a reflection. If that's all fine then take it all apart and put it back together to see if you left something out somewhere. It sounds like its not seated properly though...
     
  5. Projekt thread starter macrumors member

    Joined:
    Apr 3, 2010
    #5
    I can't believe it- I've always taken from a pool of general ram for testing and after pulling some from my main machine it turns out every single one was dead (four sticks!) - I've never seen anything like it. Thanks for the help guys.
     
  6. Rodus macrumors 6502a

    Rodus

    Joined:
    Oct 25, 2008
    Location:
    Midlands, UK
    #6
    Wow, there's unlucky, very unlucky and then you in a new league. I've never seen 4 sticks be bad consecutively. At least you're up and running now.
     
  7. macuser453787 macrumors 6502

    Joined:
    May 19, 2012
    Location:
    Galatians 3:13-14
    #7
    Glad you got it running! If it happens again, just replace the PRAM battery. Symptoms you described sound very similar to what happens when the PRAM battery needs to be replaced. Just FYI. :)
     

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