Black screen - works sometimes
I use ifixit so much and always find my answers here but now I'm stuck.
I've got an 27 inch core2duo late 2009. After booting the screen turns black (so I see the apple logo and then the screen turns black, the machine stays on and I hear the HDD). I tried the LCD on a different iMac also late 2009 and then I got it booted but after a few seconds it turned black again but you hear the HDD run. I exchanged the LVDS cables and they both do the same. I know the LCD issn't completely broken because it sometimes works...
Question is: whats causing the LCD to turn black after a few seconds?