Video Output external but not Internal
Hi here is the scenario - I have two of these macs here with exactly the same problem. We can get display to an external monitor but not to the internal LCD. The machine works perfectly on an external monitor - just nothing on the internal.
We have changed everything except Logic Board - VGA, PSU, Cables, RAM, Inverter. PRAM & SMC Reset.
Mobo LED'S show all except 4 which from what I read is normal - this should only light if there is a temp problem.
I've trawled and trawled and cannot find anything - The fact that I now have two here in the space of 2 months makes me think there is an answer to be found. The first mac was built May 2011 and the second Mac January 2012 so a big gap in manufacturing.
If anyone has any suggestions I would be grateful.
Is this a good question?