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Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

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Black/Blue screen on startup

I have an 2011 Mac running 10.12.6.  The Mac turns on but is displaying a black/blueish tint. There is no icons or cursor.  Upon turning it on, I do hear the startup chime and DVD player so I know there is power to internal parts. I do feel the fan blowing through the vents.  Nothing appears on the screen. None of the USB ports are working and thunderbolt port is not working either. If I remove the RAM, the computer does recognize there is not memory.

 The Mac was working before and it was plugged into a power strip.  So, I don't know if something got zapped. Other users thought it was the video or inverter card that is bad.

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Hook up an external monitor to help diagnose the issue. Let us know your results.

The next step would be to open it up and look at the logic board diagnostic LEDs.

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As I said before, I can’t use a wired keyboard because none of the USB ports appear to work. I tried each port by pressing the CAPS lock key and the key doesn’t light up. Also, I did try PRAM and was not successful. Also, I did connect an external monitor to the computer and that didn’t work either.

This computer is a 21.5” model. I am in the great USA.

Where are the diagnostic LEDS on the logic board? What should I be looking for?


I think you mis-read what Mayer wrote. It's connecting an external monitor to your system to see if the screen is bad.

The diagnostic LED's are located on the main logic board. Review this IFIXIT guide iMac Intel 21.5" EMC 2428 Logic Board Replacement jump to Step 32 the cable being removed covers them. Look at Step 33 and zoom the image you'll see them marked.


I'm sorry there was no misunderstanding on my part. Mayer said: "Hook up an external monitor to help diagnose the issue". This is what I said "I did connect an external monitor to the computer". Regardless it didn't make a difference.


Yes, I saw the additional entry at the end but you over focused on the USB aspect in the first part of the reply Vs stating you had tried the external. So what did the external show you? If anything.

Did you have your system plugged into a good surge suppressor or UPS? As you stated the USB ports are also not working its starting to sound like you got a surge or lightning strike which killed your system.


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Have you tried a SMC and PRAM reset? (Use a wired keyboard for this)

I’d also try starting in Safe Mode and if all else fails try Internet Recovery.

There was a recall on the graphics cards of 2011 iMacs but I think it was only the 27”. Whereabouts are you located? If you are in the EU, consumer law might still cover the iMac (6 years of repairs) as long as the machine is in perfect condition.

Let me know how it goes!

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