G5 iMac won't power up. I've got internal LEDs.


macrumors 6502
Original poster
Nov 2, 2007
Western Mass.
I have a G5 20" iMac model A1076 which will not power up. We had power outages this weekend from intense winds.

I tried resetting the SMU and other various external things to absolutely no effect. I tried using this apple support guide. I removed the rear cover. When plugging it in, LED 1 lights up and LED 2 begins flashing slowly--even before I try restarting the computer from the internal power switch. I try that switch as well as the internal SMU switch. No change. still LED 1 is lit up and LED 2 flashes.

Does this indicate that a new power supply should resolve the problem? Are there other steps I should try before buying a new PS somewhere online?



macrumors newbie
Nov 25, 2009
*not an expert* but...

That's the way the kb article reads to me. I think it's the logical next step...


macrumors newbie
Jan 25, 2010
Santa Cruz, CA
Did a new P/S cure your problem?

I gifted my wife's iMac G5 to our son a month ago after I bought her an iMac 27". Now the old machine has almost exactly the same symptoms you described. The difference is that LED 2 does not light. Did a new power supply fix your machine?


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