Is it the power supply? Lit LED, 1 none else.

LED stays lit when I plug my iMac G5 in, but when I push the power button, LED 2 flickers on for less than a second and then goes off again. The iMac stays black.

I have tried to reset the SMU by plugging it in while holding the power button, but nothing has changed.

The computer became bricked after a brief power outage (and was the only machine in the house not on a power strip).

mayer wrote responding to "Where is a decoder for diagnostic LED pattern"

LED 1 indicates that trickle voltage from the power supply has been detected. This LED will be ON when the computer is turned off and your power supply is working correctly.

LED 2 indicates that the main logic board has detected proper power

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Replace your power supply.

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Thanks. I'll order one and see how it goes!


Well it was the power supply - I'm using the computer to write this follow up. It didn't take hours to fix either - it took half an hour.

I discovered that you may not need to do more than get the front bezel off and lift up the display to swap out the power unit - the hidden connector that otherwise takes hours of disassembly to get at pulls out with a bit of firm-but-gentle sideways wiggling.

My step 18 note "If you are changing the power supply - this is a good point to remove the screws to the old power supply to see if the connectors (both of them) are accessible. If you can gently (but firmly) pull the two-wire connector out from under the chassis, you can install the new unit at this step ...

Live on iMac G5, live on!


Glad I could help you solve your problem ;-)


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I have the same problem only 1 led light up.I have an imac 27 "intel. might be power supply?

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philaro will be eternally grateful.
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