Mid 2007 Intel iMac Won't Power On

Question

Mid 2007 Intel iMac Won't Power On

My mid-2007 intel iMac 24" won't power on, there is no sound, screen activity or signs of life other than a slight "bzz bzz" when the power button is pressed. Yesterday it was working fine, I put the computer to sleep and when I attempted to wake it the next day, it would not. The optical eye on the mouse was lit and a green led light could be seen reflecting through the memory access door, but the computer made no sounds and would not wake. I held the power button until the mouse turned off and then attempted to reboot. All I get is a quick buzz (possibly the hard drive sound that you normally hear just before the chimes and screen powering on) when the power button is pressed, but no other activity. I attempted resetting the SMC and reinstalling the memory, no avail. Just a little buzz and nothing else. An

iMac, Mac OS X (10.6.8)

Posted on Feb 20, 2012 8:45 PM

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Answer 1

Jul 30, 2015 6:40 AM in response to vince1286

You can try the following which came from article My Mac randomly just turned off and now it wont turn back on, the charger light is faintly flashing green and amber?!?!

I assume you know how to take the Imac apart but this article was from a MacBook. So make the necessary adjustments.

I actually just fixed it. Here is what to do;

1. Unplug everything from your computer.

2. Take off the bottom of your MacBook / Pro / Air. (There are usually 3 screws that are longer than the rest near the vent, remember where they go.)

3. Carefully unplug the battery from the logic board.

4. Wait 10 seconds.

5. Plug the battery back into the logic board.

6. Put the bottom cover back on.

7. Reboot the computer holding the "Option" key.

It's not exactly what I did but it should work. If it doesn't work, what I really did was unplug the battery and then plugged my charger into the computer, the fans started spinning and then it shut off again. Then I plugged the battery back in, put the bottom on (with no screws), and tried booting up again. The Apple chime played and then the computer shut off. So I tried booting again holding the "Option" key and it booted up like normal. I then restarted my computer to make sure it is back to normal and it is.

Sounds like they are just resting the BIOS.

Review page 154 here http://www.scribd.com/doc/17539946/Mac-Pro-Early-2008 for LED codes and troubleshooting.

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Answer 2

rkaufmann87

Level 10

148,494 points

Feb 20, 2012 10:04 PM in response to Austin Van Laar

If it's not getting any power at all it's really difficult to pinpoint, however my guess is a power supply or main logic board. Let us know what you find out.

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Answer 3

Feb 20, 2012 9:26 PM in response to rkaufmann87

Thanks for your reply. I suspected as much. I've made my appt with the genius bar. I doubt this makes any difference, but I did notice that when the power cord is in place, one of the green diagnostic LED's near the memory slots lights up and stays lit. When the power button is pressed two more light and stay lit. The computer still makes no other signs of life. LED 2 and 3 turn off if the power button is held to manually turn off the computer. Any thoughts or still likely the PSU?

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Answer 4

Jul 30, 2015 5:19 AM in response to rkaufmann87

Dear all,

I encounter what can be very similar to what happened to Austin Van Laar.
A morning, I found my mid 2007 iMac off after having let it on at night.

The power button didn't work neither, nothing happened.
I opened the machine, and played with the diagnostic LEDs.
What I happen is somewhat weird (I think). The first-left LED gets on on plugging the AC cord, After 3 or 4 seconds, all the LEDs flash and then… nothing, strictly nothing.
Do you guys think it could be the PSU, or rather the motherboard?

Thanks in advance!

Vince

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Answer 5

Jul 30, 2015 7:06 AM in response to AgentTyler

Thanks for your advice Agent Tyler.
Actually, as it's an iMac, there is no battery, resetting the SMC should work when unplugging the AC cord and waiting 10-15sec. Some say you have to keep pressing the power button for 10-15 sec while the AC cord is unplugged, I also tried this, with no luck.
I'll try doing that again and rebooting while holding the "option" key, but I doubt it'd work as the first diagnostic LED on the motherboard stops lighting after 3-4 sec on plugging the AC cord.
I'll keep you updated!

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Answer 6

rkaufmann87

Level 10

148,494 points

Feb 20, 2012 8:57 PM in response to Austin Van Laar

If it's totally silent it sounds like a power supply, whatever it is you should take it into your local Apple Store or AASP to be professionaly diagnosed.

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