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모델 A1312 / Mid 2010 / 3.2 GHz Core i3 또는 2.8 & 3.6 GHz Core i5 또는 2.93 GHz Core i7, ID iMac11,3

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Chime Loop / All 4 LEDs on / Commands not working

First of all, the correct iMac model is:

  • Apple iMac "Core i7" 2.93 27-Inch (Mid-2010)
  • Identifiers: Mid-2010 - MC784LL/A - iMac11,3 - A1312 - 2390

The iMac was working like a charm for years, and then, i was just checking my emails, the screen just went into some kind of grey pattern - I had to force shut it.

When I tried turning it on again, the chime loop set in. In a first try, I was able to boot it in safe mode holding down the shift key, where I got to the login screen, before the exact same thing happened again (weird grey screen and nothing working anymore). Force shut down again.

Since then, booting the machine was not possible anymore. None of the boot up key commands work anymore.

After doing some research, I decided to open the iMac to check the 4 diagnostic LED's on the logic board, just to find out that on this specific model, the 4 LED's would also be visible from the outside (bottom) haha.

However - when pushing the Power button, all 4 LEDs are switched on, solid and not flashing.

  • First of all, any chance my iMac can still be saved?
  • Second, if none of the boot up commands work, how can I retrieve my data?

Thanks in advance

답변되었습니다! 답변 보기 저도 같은 문제를 겪고 있습니다

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Hey everybody, I am happy I was able to resolve this!

A short overview over the symptoms:

  • Endless Chime Loop
  • Black Screen
  • Keyboard startup combinations not working
  • Boot from CD (holding C) also not working

On this specific iMac model, the 4 LED’s are very hard to see (because they can only be seen through the tiny holes at the bottom of the aluminum frame). It took me a while to make sure that in fact, only 3 of them were on when trying to boot.

Solution:

After watching some videos on the web, i noticed that LED1(power) always stays on, LED2 (power to logic board) and LED3 (graphics card) will turn on at the same time, and that LED4 (screen) will turn on last, simultaneously with the first chime. I think this is the same for ALL 2009-2011 iMac models. Even though I wasn’t able to see which of the 4 LEDs wasn’t on, I was able to identify the missing LED as LED3 after removing the Screen, as well as the graphics card.

As I don’t want to spend hundreds of $ on a new computer, my only option was to go all in and try repairing the graphics card (ATI Radeon 5750). My next option would have been to buy a replacement graphics card from ebay. Disconnected it from its metal frame, cleaned the silicon paste off it, and put it in the oven at 200 degrees for around 10 minutes.

Put it back in, biting my nails and hoping for the best…. and BADAAAAAM no more chime loop, mac turned on just fine. This is like a miracle now.

I know that eventually the same thing, or even worse, could happen again at anytime - But at least I am prepared now. I immediately backed up all data - and can live on as a happy human.


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Thanks for sharing. What is the logic behind to put the GPU into oven at 200 degree ?

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Let be answer your last question first as yes we can still salvage the data off of your drive. Using a tool like this Universal Drive Adapter so you can access the data by another Mac system.

It still might be possible to get your system into Target Disk Mode which will also allow you to gain access to the systems drive. This also might give us a clue on whats happening here as a diagnostic step.

Reconnecting the display and putting it back on see if you can restart the system but hold the T key at the same time until the system is booted up you should see a FireWire icon dancing on your screen did that work?

Reference: Mac startup key combinations

Universal Drive Adapter 이미지

상품

Universal Drive Adapter

$24.99

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Hi Dan, thanks for your support.

I already put everything back together, and, like I wrote, none of the startup key combinations is working. The iMac just doesn't react and immediately falls into the Black-Screen-Chime-Loop.

However, i fear that the keyboard might not be connecting well (apple wireless keyboard). I'm going to try it with a wired apple keyboard later today.

Also what I haven't tried yet is booting the mac from the orginal CD ( i think it was osX 10.6

Will update you but my hopes are low!

Yes, you'll need a USB keyboard on this older series otherwise it's not likely to see the keyboard in time. Focus on the Target Disk Mode test here. The drive/CD boot up is a bit later in the list of things that happen at boot up. I want to get to an earlier timepjoint which Target Disk Mode will allow us.

USB keyboard brought no change. none of the start up key combinations work. tried booting from the cd - not working because the C command is not recognised either.  the mac spits out the CD every 3-4th time i tried to reboot, but nothing else happens. It stopped that now, so the CD is lost. do i have to bury the mac or any final advice?


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