Dead Display, system starts fine
Display went to black.
But starts fine. Machine is reacting on change of speaker volume.
Starts perfectly in terminal mode (but black).
Alt-cmd-R.P reset doesn't work out.
External Monitor attached : nope.
Running iMac as an external Monitor on a macbook: negative (maybe wrong cable, or the function for F1, F2 is disabled in sytem prefs.).
What couldit be:
Display or GPU?
Usually, if a graphic card is saying good-bye, you see some errors on the screen before. But this time not. Just turned black some day when booting.
I've removed the display , yet. Is there a diagnostic method of testing, weather display or graphic card is the problem? Or Backlight?
Is this a good question?