Chosen Solution
Hi. So I have a 2011 21.5” iMac. It works perfectly fine except the screen won’t light up but if I connect the iMac to my TV I can see on the TV. So what would be causing my screen not to work? The screen itself is not faulty as I have 3 other lcds which I have tested and they all work. Would this be the digitiser? What would be causing it not to show up? Ps. All the ports on the logic board are fine so it’s not that.
Take a flashlight and set it on the screen at a sharp angle can you see the faint image of your desktop and its icons? If you can that points to the backlight. If you don’t then the LCD its self has a problem. To fix the backlight will require a new LED driver board, Apple P/N 661-5976 and here’s the guide: iMac Intel 21.5" EMC 2428 LED Driver Board Replacement as long as the cables are not damaged. A bad LCD will need either new cables or a new display
