imac g5 won't power on

Discussion in 'Mac Basics and Help' started by jakeblues, Feb 10, 2015.

  1. jakeblues macrumors newbie

    Feb 10, 2015
    I have a g5 iMac that won't power on. When the power cord is plugged in, LED1 is on, which (according to the Apple support website) makes me think the power supply is ok. Correspondingly, I think the logic board must be bad. But I've replaced it twice now, and neither of the replacements has worked.

    Is there anything else that could prevent the machine from powering on other than the logic board or power supply?

    Is it possible that the power supply could be bad even though LED1 lights up when power is connected?

    Thanks for any help!
  2. Mr Rabbit macrumors 6502a

    Mr Rabbit

    May 13, 2013
    The power supply COULD still be bad although, as you've read, LED 1 typically rules that out.

    Have you inspected the logic board and/or power supply for bulging/blown capacitors? (image for reference: )

    If you shine a light through the ventilation holes of the power supply you should be able to see the capacitors inside.
  3. jakeblues thread starter macrumors newbie

    Feb 10, 2015
    I haven't looked carefully at the caps on the logic board, but since I'm now on my third one and getting the same effect, it would seem that all three would have to have some bad caps; which isn't impossible, but does seem like a coincidence.

    I definitely have not checked any of the caps in the power supply. I appreciate the suggestion to try that out.

    It's also possible I haven't installed the logic board correctly, or failed to do some crucial step. The only "not-obvious" thing seemed to be cleaning the thermal compound off of the heat sink and applying new compound -- which I did -- but other than that I just connected everything up exactly the way I had taken it apart when removing it.

    Thanks for your reply!

Share This Page