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Old Sep 21, 2010, 04:26 AM   #1
mutto
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24" iMac - won't power on!

Hi,

I was using my 24" Alu iMac on Saturday when all of a sudden is went dead. Now it won't power on!

I've changed the power cable, which hasn't solved the problem and I've tried resetting the SMC.

Now, I suspect the power supply is shot, but before buying a new and replacing it how can I be sure it is actually the psu that has died and it's not something else and/or the logic board??

Any help gratefully received!

Cheers
Martin
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Old Sep 21, 2010, 08:29 AM   #2
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There isn't really a way to tell what has gone bad. You could take it to Apple and let them have a look. You can ask from them what is wrong and then replace it yourself if you want
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Old Sep 21, 2010, 03:35 PM   #3
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I was having the same error on my 20" Imac. I would push the power button and the circle would light but then just stop. $90 charge to find out my ram went bad.

if you have any other ram try that before taking it in? good luck!
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Old Sep 29, 2010, 07:55 AM   #4
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Update:

I've installed a new power supply - it didn't fix the problem, the iMac still won't power on!

One other thing, when my iMac was working I've always found that the power on button needed to be pressed a few times for it to come on, not all the time just sometimes - or I had to hold down the button for a few seconds to make it come one.

I wonder if the actual power switch has gone kapput? Would do you think? Is it easy to replace?
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Old Sep 29, 2010, 09:25 AM   #5
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Is there diagnostic LED's on the Intel 24" iMacs??

A few people have mentioned them, but I thought they were on the earlier models?
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Old Sep 29, 2010, 09:48 AM   #6
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Originally Posted by mutto View Post
Is there diagnostic LED's on the Intel 24" iMacs??

A few people have mentioned them, but I thought they were on the earlier models?
There are LEDs on your MLB. What LEDs are lighting up when you plug in your power plug. You should see 1 LED on far left light up, which should indicate that you have trickle power. Then you know your PS is good.

Try reseating your RAM.

Let me know about the Diag. LEDs.
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Old Sep 29, 2010, 09:53 AM   #7
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OOh, I'll do this when I get home and post the results!

Cheers
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Old Sep 29, 2010, 10:13 AM   #8
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OOh, I'll do this when I get home and post the results!

Cheers
Let us know mate
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Old Sep 29, 2010, 12:14 PM   #9
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Ok, here we go, power cord is plugged in,turned on at wall.

From the left

1. Green light on
2. Off
3. Doesn't seem like there's an LED here anyway
4. Off

This is with the NEW power supply installed, yet it still won't turn on.

Cheers
Martin
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Old Sep 29, 2010, 12:22 PM   #10
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Another thing, as soon as I hit the power on button the number 1 LED goes off.
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Old Sep 30, 2010, 01:35 AM   #11
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I to have problems with a 24 iMac (late 2009)all i get is one loud beep space loud beep

with a black screen

actions taken

in for repair at local repair centre ,returned four days later ,logic board replaced
24 hours later it failed again , return to repair centre

got it back three days later they say the ram was faulty

this time it lasted 2 hours

the repair centre also sell apple computers , the manager said because they did not sell it to me they cannot do any more than keep repairing it ( read into that what you will )

called Applecare ( it does have applecare ) after the usual phone shuffle got up the ladder , they are now sending it to a different repair centre I am not holding my breath

It seems to me that the people who do not have access to a Apple store are treated differently to those that do
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Old Sep 30, 2010, 03:57 AM   #12
FarSeide
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Quote:
Originally Posted by mutto View Post
Ok, here we go, power cord is plugged in,turned on at wall.

From the left

1. Green light on
2. Off
3. Doesn't seem like there's an LED here anyway
4. Off

This is with the NEW power supply installed, yet it still won't turn on.

Cheers
Martin
Looks like its your logic board issue as it is not getting power from your PS to the logic board. I hope you have Apple Care as its not getting power.

I would assume that you FAN doesnt kick in or it tries to but it stops.

Am I correct ?
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Old Sep 30, 2010, 05:19 AM   #13
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The fan doesn't come on, or even tries too.

I've had the iMac for 18 months and have no Applecare.
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Old Nov 8, 2010, 06:39 AM   #14
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my 2008 intel core2duo 24" iMac also crashed yesterday: it froze and the screen went black.
Now when I try to restart it, I have the usual startup sound, and the fans are running, but that's all: black screen, no hard drive sound, nothing more.
I tried to unplug/replug it, remove/reinstall the RAM (in that case I get loud bips from the speakers).
I'll try the LED diagnostic as above, but let's assume it is the motherboard (which I think it is since no display nor the disk move), do you have an idea of the price to replace it, and if it can be done by myself?
What I fear is that it'll cost more than half the price of a new model, without any guarranty that it'll run very long.... from what I read in this thread, I see that some repairs just last a few hours!
Thanks,
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Old Nov 10, 2010, 10:43 AM   #15
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I still haven't got round to visiting the Genius bar to get it fixed.

I was going to have a go at replacing the logic board battery, but noticed that 2 of the Torx screws that hold the cover on are stripped - there's no way it's coming off without have the screws drilled out, something I'll leave for Apple to do, that's if they will do it???????
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Old Jan 25, 2011, 05:40 PM   #16
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if there are still some people with that problem, I had my iMac fixed: it turned out to be an issue with the graphic card. Even with that I could not start in target mode.
I found a tech who could "fix" the card, and not replace the whole thing. Cost me 270, I wouldn't have made it fixed if it was for more
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Old Jan 25, 2011, 07:02 PM   #17
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Originally Posted by charlie105pb View Post
if there are still some people with that problem, I had my iMac fixed: it turned out to be an issue with the graphic card. Even with that I could not start in target mode.
I found a tech who could "fix" the card, and not replace the whole thing. Cost me 270, I wouldn't have made it fixed if it was for more
Did your have the nvidia 8800GS GPU?

Cheers,
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Old Jan 26, 2011, 01:05 AM   #18
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sorry I did not give the specs:
iMac 3.06GHz - 24-inch screen - RAM 4 Go
NVIDIA GeForce 8800 GS

and I forgot: the iMac broke down while using a 3D game on Windows (boot camp)
The technician seemed to think that when the Mac boots on the PC partition, it may not be protected for over-temperature (the computer won't necessarily stop, and not sure if the fans speed increase accordingly)

When he fixed it, he said the thermal paste between the chip and the radiator was completely dry: he did not know why, but he did not think it was the reason for it to heat to much.

I just hope the repair will last some time, he only guaranties it for 3 months!
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Old Jan 26, 2011, 05:57 AM   #19
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Check with Apple....the NVidia 8800 GPU is a known issue on those iMacs - I've read that Apple is even repairing them for free out of warranty. You may be able to get reimbursed for your repair.
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Old Jun 13, 2011, 06:29 AM   #20
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Apple have replaced the rear casing and power switch, which hasn't solved the problem.

They are going to change the power supply next, again.
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Old Jun 21, 2011, 02:21 PM   #21
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Apple confirmed logic board is the fault.

Thanks Apple, my iMac lasted 18 months and cost circa 1300.

Nice one.

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Old Jun 21, 2011, 02:41 PM   #22
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Check with Apple....the NVidia 8800 GPU is a known issue on those iMacs - I've read that Apple is even repairing them for free out of warranty. You may be able to get reimbursed for your repair.
Yep, that was my case even after warranty...Apple's service is second to none, provided you present them the necessary arguments in this specific situation.
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Old Jun 21, 2011, 03:05 PM   #23
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Apple said it would cost me 414 for a new logic board.

I'll probably end up stripping it for parts on eBay.

So angry that it only lasted 18 months!!
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