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

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iMac 27" 2010 Chime loop and black screen issue

After system update (High Sierra) I get a black screen and the start up chime continuously loops. Keyboard commands do not work neither does putting in an OS X disk as the disk drive.

I also tried to plug in an external display (MacBook) using a Mini Display Port to Thunderbolt cable and I've got no signal.

Removed all RAM (4x2GB) got error beeps, put 2 back on and got the chime loop with the black screen.

Diagnostics LEDs: #1 is always on, #2 and #3 are on when the iMac is started, #4 is off.

What could be the cause of this issue? The computer has been working perfectly until now.

Answer this question I have this problem too

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Your MacBook won't work as an external display. You can hook it up via the Fireport and try to access the iMac's hard drive using Target mode. But my bet would be on a failed GPU. It will probably need to be replaced. I have also had about a 70% success rate with doing a hot air workstation reflow.

iMac Intel 27" (Late 2009 or Mid 2010) Graphics Card Replacement

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Hi Mayer. I'm having this exact same issue, same iMac model. None of the startup commands work. Just black screen and endless chime.

After doing some research, I decided to open the iMac to check the 4 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 - all 4 LEDs are on, solid and not flashing. This leads me to the assumption that the Logic Board could be broken?

The iMac was working like a charm, 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. After that - Booting the machine was not possible anymore (as described above). None of the boot up key commands work.


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