Chosen Solution
Hi, I have an iMac 2011, 21,5" EMC 2428. Right after the boot chime, the backlight goes on for a short period and then stays off forever. It seems that the LED backlight isn’t working anymore, because if you use a flashlight you can see everything on the internal screen. There is an interesting situation where a backlight appears in a short time when it is woken up. I have opened system to check the onboard diagnostic LED’s 1 ~ 4, all are turned on. Has anyone encountered the same situation? Thanks. Richard
You’ll need to replace the backlight LED driver board iMac Intel 21.5" EMC 2428 LED Driver Board following this IFIXIT guide: iMac Intel 21.5" EMC 2428 LED Driver Board Replacement Update (01/08/2019) What does the NVRAM require to hold its settings?
I would start there.
Hello, It’s possible that it is a bad AMD graphics chip as well. If your iMac has the HD 6970 or HD 6950 this a really common failure, Unfortunately there were never updated cards for this machine to fix the GPU defect. If there is no image it’s likely the GPU. You should check if you have an image on the screen, by using bright light held against the LCD panel. You should be able to see something on the screen if the panel is getting an image I would definitely look at replacing either the backlight driver board.
Hello, same problem here. The iMac works with external display and also do detect its internal display. Tried to change the backlight inverter board but same problem. Now even with the flashlight I can see nothing. Can be really the GPU?
