iMac G5 won't turn on

Discussion in 'iMac' started by alywa, Apr 21, 2011.

  1. alywa macrumors 6502

    May 6, 2004
    Hey all...

    I'm using an iMac G5 (Rev B, 2.0 GHz)... yeah I know it's 6 years old. Anyway, it has been an absolute workhorse for the past 6 years, but yesterday it died on me. For a couple of weeks it has been occasionally turning itself off (no warning... just shutting down)... yesterday it turned itself off. I turned it back on, got the "bong" sound, and then it promptly shut itself off again. I repeated this a few times, and finally it just stopped turning on completely... no beeps or other sounds, no signs of life (ie no screen flicker, no fans, nothing).

    I opened her up, de-dusted, reseated the RAM, but still nothing. Any ideas, or is it just time to get a new one? If I do get a new one, what should I do with the old one (I'll need to remove the HD... I have work / patient sensitive material on it).

    Thanks in advance,

  2. thehighesttree macrumors newbie

    Apr 21, 2011
    Doesn't sound good...

    Had the exact same computer as you. Turns out the capacitors on the logic board are crap and the computer died in much the same way you described. Did your screen do anything funny when it froze or did the whole system just shut off? In any case I think it's probably those caps, and if so, good luck finding replacements (they're 6.3V 1800uF capacitors, hard to come across any that are small enough for the iMac G5's form factor). There are some instructions online for diagnosing this, but basically what you should do is remove the back of it, plug it in and try booting it up. You'll see a small panel with 3 LEDs on it: on a healthy system all 3 will fire up, but in my case only the first 2 did.

    Check Apple's diagnosis page and follow the instructions there. Yours should be the "ambient light sensor" model.

    I know it sucks but your computer's probably toasted. If it is, you can still fish the HD out and put it in a Serial ATA external box so that's something. Good luck!
  3. wrldwzrd89 macrumors G5


    Jun 6, 2003
    Solon, OH
    This issue sounds like either a logic board problem or a dead power supply. PSUs are even more workhorses than most realize... but even they die eventually.
  4. alywa, Apr 21, 2011
    Last edited: Apr 21, 2011

    alywa thread starter macrumors 6502

    May 6, 2004
    LED info

    Thanks for the responses guys. I checked the LEDs... the 1st one is on, which indicates the power supply is receiving power. I held down the power prongs (where the power switch hits), but no other LEDs light up. I followed the instructions in the link above, and it still didn't power up. Looks like a logic board failure. Anything else you guys think I should try? Just for disclosure, I just ordered a new 13" MBP because I can't be without a computer for for very long at work, so it's not critical to get this one fixed, but I do hate for things to break.

    Are there any good parts / repair outfits that may want to buy this machine for a parts computer?


  5. CubeHacker macrumors 65816


    Apr 22, 2003

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