ive got a pretty old mini-cabinet and my arcade monitor looks like its made by JVC in 1985. 20",its an old tv from the looks of it

it had moon cresta installed in the box.
The picture's pretty good but this is my first project and i am still having teething troubles!.
I cant find the v.size pot or centering, all it seems to have is one marked `screen` and ` focus ` and three pots on the neck board, i guess these are the r-g-b gun pots?. some of the picture is cut off on the top and bottom.
i am using an arcade vga card and j-pac in my pc, also at certain resolutions in mame games the screen just rolls, maybe too high for the monitor?.