LED Display Not Working on iMac Mid 2010
My iMac has a display problem. Works perfectly well with an external monitor plugged in so I've ruled out the graphics card. It started off just going blank after a couple of hours use. Then it wouldn't come on at all. Just a quick flash when it was booting and nothing after that. I've tried looking at it with a torch to see if it's just the backlight but not able to see anything.
When the LED ribbon cable is connected to the logic board the external monitor works as an extended desktop. When I unplug the cable the external monitor works as the main display.
Thinking it's either the LED that needs replaced or the backlight inverter board but no idea really. Suppose it could even be the logic board itself! Any suggestions on how to narrow the problem down to one thing or the other would be greatly appreciated.