Model A1312 / Mid 2010 / 3.2 GHz Core i3 or 2.8 & 3.6 GHz Core i5 or 2.93 GHz Core i7, ID iMac11,3

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Power on intermittent on iMac 27" mid 2010 EMC 2390

First time today, tried to turn on my iMac and no power, no beeps, no nothing. Unplugged all USB devices, still nothing. Unplugged the power cable, waited 30 secs or so, plugged it back in, waited another 20 secs. or so and it powered up.

Shutdown, then pressed the power button, it came right on. Shutdown completely, waited about 5 mins. and tried to power back on, nothing. Unplugged for about 30 mins. Plugged it back in and it powered right up. Is this a sign of the power supply maybe going bad or could the power button be the issue? I'm not sure by clearing the SMC solved anything.

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Open it enough so that you can observe the diagnostic LEDs to the right of the RAM slots to see if #1 LED is staying on, indication that the power supply is getting trickle power and let us know. Also observe how much dust is inside. Be careful that the screen does not drop and rip out the video cable while doing this.

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Here's what I'm seeing. I unplugged it from my UPS to make sure that plug hadn't suddenly gone bad. I plugged it right into the wall, still wouldn't power up. After leaving it unplugged for about 30 mins. and plugging back into the wall, it powered up and worked fine all day. Not a UPS issue. When removing the plug from the wall and back into the UPS, no power. #1 LED not lit and not much of a dust issue, I've seen far worse. Leaving it unplugged for about 15 or more mins., plugging back into the UPS, waiting about 30 secs. (SMC reset), it powers up just fine. So, it seems if I never remove it from a power source, it will work for now at least.


The spell checker change trickle to triple. No green LED#1 means it is getting no power. I have not seen a bad power supply do this. I'd let it run till it fails. Has the power cable been damaged?


Sounds like you may need a new battery in the UPS.


I have the same problem with a late 2009 21.5in. iMac. No solution yet. Daniel, did you fix yours?


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daniel will be eternally grateful.
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