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Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2

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Why does the diagnostic LED1 turn on after hours?

I've been troubleshooting an old iMac 2011 27". After removing the screen I could use the diagnostic LEDS to gain some info.

When LED1 is on, the machine can be booted without problems. After disconnecting/reconnecting power this LED stays off. It can take hours till LED1 turns back on. After that it boots without a problem.

Am i correct to suspect a bad PSU for this behaviour? I just want to make sure before ordering a piece worth more than the Mac :)

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I would double check the AC power, a bad ground can send you down the wrong path. Get a simple outlet checker and also check the cord by trying a second cord and check the system socket.

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DieterL crwdns2934231:0crwdne2934231:0
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