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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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My iMac doesn't turn on, fans spin

I have an iMac 2011 21.5 that when you press the power button, the chime sound plays, but nothing is displayed, I tried to leave it there, and the fans go like normal, but nothing appears on the screen, it's not the screen, nor the SSD (I think), because I tried to boot from an external hard drive and, the chime plays, but again, nothing appears on the screen, yet I know that the screen works because, before the problem started, the screen worked perfectly (I didn't dissasemble it) but the iMac normally restarted because of a problem and it became unresponsive, i tried resetting the MLC but it doesn't work! Help!

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From the sounds of it the displays backlight has failed. To validate that’s the case press a bright flashlight against the display at a sharp angle you should see the faint image your desktop icons. If you do that’s tells us that’s the issue.

There are two possible common causes, either the iMac Intel 21.5" EMC 2428 LED Driver Board has failed or the backlight power cable has been damaged or disconnected as described in step6 here iMac Intel 21.5" EMC 2428 LED Driver Board Replacement.

crwdns2886500:0Replace the circuit board assembly that powers the display backlight in a Model A1311 Late Mid 2011 21.5" iMac.crwdne2886500:0

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iMac Intel 21.5" EMC 2428 LED Driver Board

$29.99

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Thanks! I'll check when I get the suction cups for the screen!

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@bgest - No need to open the system with the test to validate things. Just aim the flashlight into the display it acts as a backlight of sorts. Let us know what you discover before you open the system.

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It doesn't work, only 1 and 2 diagnostics leds power on

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@bgest - Where you able to shine a light into the display to help isolate the issue?

If with the display fully connected when you looked at the onboard Diagnostics LED, then the GPU board will need to be inspected for possible Capacitor failure, if nothing found then it’s likely the GPU board will need replacing.

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