iMac G3 Not Powering On.

Goftrey

macrumors 68000
Original poster
May 20, 2011
1,853
70
Wales, UK
I have used my Rev.A Bondi-Blue iMac for a good while now solely as a jukebox. It's been doing the same task flawlessly for months, day in, day out - until today.

When the power cable is connected to the iMac, the computer (haven't located where abouts the noise is coming from) makes a very high pitched, tinnitus-like noise. Then, when I push the power button in - the noise becomes louder.

I tried to record both a video & audio sample but the mic. just won't pick up the sound.

There's no startup chime, fans, display. Nothing.

Any ideas?
 

Goftrey

macrumors 68000
Original poster
May 20, 2011
1,853
70
Wales, UK
I finally got around to opening the iMac up & diagnosing the issues & it looks like you guys were right. A couple of leaking caps on the PSU board.





 

Intell

macrumors P6
Jan 24, 2010
18,881
368
Inside
Those black things with the yellow tops aren't capacitors, those are transformers. They're supposed to have that gunk on them. They extremely rarely go bad. The only ones that I know of going bad under normal use are the flyback ones.
 

Goftrey

macrumors 68000
Original poster
May 20, 2011
1,853
70
Wales, UK
Those black things with the yellow tops aren't capacitors, those are transformers. They're supposed to have that gunk on them. They extremely rarely go bad. The only ones that I know of going bad under normal use are the flyback ones.
Oh! Well that's good news I guess.

If it's not caps then what on earth could the issue be?
 

Intell

macrumors P6
Jan 24, 2010
18,881
368
Inside
I would suggest replacing the power supply with a known good one or even all of its capacitors. Just make sure you get the right revision power supply. The tray loaders had two different power supply revisions.
 

Goftrey

macrumors 68000
Original poster
May 20, 2011
1,853
70
Wales, UK
I would suggest replacing the power supply with a known good one or even all of its capacitors. Just make sure you get the right revision power supply. The tray loaders had two different power supply revisions.
Just had a quick look around & it doesn't seem economical to buy the power supply as a part when you go & buy a fully working one for the same price or even cheaper.

Guess I'll do something funky with it in the future. Thanks for the help :)
 

MisterKeeks

macrumors 68000
Nov 15, 2012
1,832
25
Just had a quick look around & it doesn't seem economical to buy the power supply as a part when you go & buy a fully working one for the same price or even cheaper.

Guess I'll do something funky with it in the future. Thanks for the help :)
If you have a multimeter handy I would try seeing if you can get any power out of the power supply.

You might be able to get a very low wattage power supply and use it instead. I believe that the G3s had an 80 watt PSU.