Question about Apple iMac G4 Desktop

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G4 imac won't power up every time

Hi there
I have been a loyal lurker to the site for far too long. I now break my silence with a question!
I have an Apple iMac 700MHz 15" Flat Screen (now 1gb ram) (M8672LL/B). It consistently fails to power up.
I've replaced the PRAM battery. The problem prevailed. I replaced the cable. No luck. A Hardware Test ran overnight, nothing showed up. I re-installed. No help.
I cleared out the dust from the base with a hoover. It worked for a short while, then the problem came back. There is a clicking/tapping sound that can sometimes be heard from the base when it's plugged into the mains and isn't powering up. Resetting the Power Management Unit seems to help power up the mac, but it's never a permanent fix. 
I'm all out of ideas! Does anyone have any ideas what could be the problem. I love this mac. It's part of the family - it's my baby! I know mac parts aren't cheap, but I really want to save this mac from the dump.
Any help is much appreciated!
Thanks for reading
Luke

Posted by on

  • soselective Feb 09, 2009

    Thank you Allanster




    I suspect you a right! I'm located in the UK though :-(


    Many thanks for the advice!
    Luke

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Had a similar problem I'm working on right now for my G4 MDD. I had fixed the power on switch by resoldering it to the circuit board (that way the external button made good contact with the internal switch). It worked for two days till it had the problems you're describing. (Light goes on, some clicking, etc.) but no "ignition". Every time I reset the pmu, the external button would power up fine. My wife finally pointed out that I had stuck in a couple ram chip my friend gave me while I was working on the switch. I checked "about this mac" and realized both they failed the startup test. I took them out and the external button has worked the last dozen times I've used it. Keeping my fingers crossed...

Posted on Mar 03, 2009

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Bummer, sounds like power supply. I used this guy when the logic board went out on my powerbook and it's been purring away for 18 months since. I spent days searching for cheapest parts and most reliable service and turns out he was both! Apple wanted $1200 for new board (no warranty) and he repaired with warranty for $350. You can check out the testimonials page if you're leery (like I was).

Posted on Feb 03, 2009

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Posted on Jan 02, 2017

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