I'm pretty sure its a mini pot, but I'm afraid to turn it! Oh what does it do!?
Bottom left hand corner labeled tc1
(http://home.freeuk.net/markk/Consoles/snes-mb-modif-big.jpg)
I don't want to turn it and not get it back to the right setting if its gonna jack it up. :unsure:
From its position, I would guess it's a variable capacitor. Looks like it's probably for trimming the crystal oscillator next to it (little can thing). It's there to allow the frequency of the oscillator to be adjusted towards the frequency it should be.
Not sure why this would be needed though, as the colour encoding is done elsewhere on the board. The colour carrier is about the only thing I can think of that is frequency critical.
yeah, i reckon youre right about it being a variable cap.. but also like you, i dont know why it would be where it is
TC1 would seem to stand for 'trimmer cap' It's probally a load cap for the crystal.