iMac Not Powering On; all 3 LEDs are unlit

Question

iMac Intel 20" EMC 2105 and 2118

Model A1174 with 2 GHz Core Duo or Model A1207 with 2.16 or 2.33 GHz Core 2 Duo

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bigmark @bigmark

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crwdns2931729:0crwdne2931729:0: Huk 17, 2015

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iMac Not Powering On; all 3 LEDs are unlit

Hi!

I have a late 2006 iMac "Core 2 Duo" 2.16 20-Inch (A1207; last of white plastic models). It's been fine until today, but is suddenly powered off and won't turn on--no noise, lights, fans…nada.

I've:

- reset the SMC

- tried different power cords and outlets

- removed and reseated RAM

- opened it: none of 3 diagnostic LED lights are lit

At this point I'm assuming it's the power supply, but wanted to make sure before I buy another. Thanks!

- Mark -

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score 2 · Answer 1 · 2015-11-17T12:21:03-07:00

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mayer @mayer

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MacHale Enterprises

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crwdns2931729:0crwdne2931729:0: Huk 17, 2015

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Here's how to do it: iMac Intel 20" EMC 2105 and 2118 Power Supply Replacement

Apple Part #: 661-3780

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Thanks, Mayer: I've seen your many posts on this topic. I just wanted to ensure it was the power supply before I replace it; I've actually done it before on another iMac.

crwdns2934271:0Huk 17, 2015crwdnd2934271:0 bigmark crwdne2934271:0

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Asim @samurai crwdns2934065:0crwdne2934065:0: 1 1 · Answer 2 · 2016-01-20T19:21:13-07:00

Asim @samurai

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crwdns2931729:0crwdne2931729:0: Sun 20, 2016

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I have the same problem for exactly the same model. However, when I opened up and plugged the power cord, the first LED did light up. I unplugged the power cord and plugged it again, but this time the first LED did light up. Not sure if I assume the problem to be with the PSU or some other problem because of the fact that it turned on the first time. Please help.

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Correction - I meant to say the first LED did NOT light up subsequently

crwdns2934271:0Sun 20, 2016crwdnd2934271:0 Asim crwdne2934271:0

If you have exactly the same problem, the solution would be the same. Which you don't but the solution is still the same.

crwdns2934271:0Sun 20, 2016crwdnd2934271:0 mayer crwdne2934271:0

Please note that there is a variation to my problem in the sense the first LED turned on the first time but not after that. Can I assume this to be a PSU failure?

crwdns2934271:0Sun 20, 2016crwdnd2934271:0 Asim crwdne2934271:0

#1 LED will come on most of the even in a failed power supply. It means it is getting trickle power to it, not that it works. #2 will light if it works.

crwdns2934271:0Sun 21, 2016crwdnd2934271:0 mayer crwdne2934271:0

Thanks mayer. I'm pursuing the option of replacing the PSU. I opened up my iMac and got to the extent of removing the LCD screen. I took the shortcut (replacing PSU) route in your repair guides. However, I have hit some roadblocks. I'm unable to take out the bottom screw of the HDD bracket. It just keeps rotating but wouldn't come out. At the same time, I noticed that the HDD won't come out even if I manage to remove the screw as I notice that the HDD seems to be fixed on the other parallel side as well, perhaps screwed to the rear case frame or something. But I may be wrong. At this point, I'm thinking of removing the logic board (which I don't want to do as I'm not an expert and there seem to be lot of careful steps involved). Please advice. If my iMac works with replacing the PSU, I was hoping to upgrade my HDD as well. Please advice how to go about this. Thanks a lot for your help.

crwdns2934271:0Sun 23, 2016crwdnd2934271:0 Asim crwdne2934271:0

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iMac Intel 20" EMC 2105 and 2118

iMac Not Powering On; all 3 LEDs are unlit

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