Model A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor

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iMac not booting up at all when connected to power cord

I have a iMac mid 2011 27" with the power cord plugged in.

Pressed the power button multiple times it doesn't want to boot up. I tried unplugging and replugging the cord again and still doesn't want to boot up. There is nothing on the screen. It's completely black blank.

I was wondering if it was the power cord or the system itself. If it's the system (especially the logic board) I can forget about it.

But, what can do from there?

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Can you give us the exact model here. Apple has made quite a few different versions. To help you look at the bottom of the foot to find the serial number then plug it into here: EveryMAc - Lookup. Then paste your systems URL here for us to see.

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As long as you're sure the power cord and the outlet its plugged into are good. I would suspect the power supply is having problems. Here's the IFIXIT guide: iMac Intel 27" EMC 2429 Power Supply Replacement.

But, before we jump here after you remove the display you should spy the diagnostics LED's, which are located near the memory slots often a piece of black tape is covering them. Here's the diagnostic chart on what they mean:

  • 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.

For now lets focus on LED 1 & LED 2 to see if the logic board is getting power at all and working correctly.

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