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Hi, So after working for 9 years flawlessly my mid 2011 iMac has black screen. The computer works fine because I have an external monitor attached to it and I am able to mirror the displays and use the external monitor. What do you think is the problem, I want to try and fix it myself? Is it the video card that apple willingly replaced in 2013? https://9to5mac.com/2013/08/16/apple-ope… Or could it be something else? I installed TG Pro and on the display of TG it tells me the CPU fan is not working. I wonder if this could be the problem, due to dust build up? Any help would be greatly appreciated. Thanks.
Sadly its likely the GPU gave up ;-{ But let’s make sure! Time to pop the display off and inspect the onboard diagnostic LED’s. Follow this guide iMac Intel 27" EMC 2429 Display Replacement If you can stop at Step 4 with the system powered and turned on carefully lift eh display up enough so you can see the LED’s
The LED’s will be backwards looking from the top. Be careful not to pull on the cables! Here’s a breakdown of the onboard diagnostic LED’s: LED 1 - Indicates that the trickle voltage from the power supply is detected by the main logic board. This LED will remain ON while the iMac is connected to the AC power. The LED will remain on even when the computer has been shut down or put to sleep. The LED will turn off only if the AC power is disconnected or the power supply is faulty.LED 2 - Indicates that the main logic board has detected proper power from the power supply when the computer is turned on. This LED will be ON when the computer is turned on and the power supply is working correctly.LED 3 - Indicates that the computer and the video card are communicating. This LED will be ON when the computer is communicating properly with the video card. If LEDs 1 and 2 are ON and you heard the startup sound, but LED 3 is OFF, then the video card might be installed incorrectly or need replacement.LED 4 - Indicates that the computer and the LCD display panel are communicating. This LED will be ON when the computer is turned on and video signal is being generated. If the LED is ON and there is no image on the LCD display panel, the LCD display panel or inverter might be installed incorrectly or need replacement. What did you discover?
