Thread
AB adjustments behind plastic cover on Classic?
So, under that cover panel on the Classic just above the power switch, there are what appear to be two unlabelled adjustable potentiometers or such on the analogue board... I've never known or particularly cared what they are for, but assumed they probably relate to display V- and H-position or some such thing, and now my curiosity has gotten the better of me and I must know. Anybody shed some light?
Brightness is lower I think. Upper is either contrast or focus - I use it to sharpen the display.
That would make a degree of sense also given the lack of external brightness control knob. Cheers! 
Yes, but its controlled via software anyway. So it more of a way to hardware set the max brightness.
Yeh I can't see too many circumstances where the brightness would need to be hard-altered unless an actual compoonent was failing and causing the screen to dim... there seems to be plenty of brightness reserve left at the default halfway point.