The current version of CoCoVGA is known to be compatible with revision B Color Computer 2 mainboards and US Tano Dragons. This page will help you identify your Color Computer 2 to determine whether CoCoVGA will work in your system.
Color Computer 2 Rev B Mainboard
From the outside
A rev B board CoCo 2 can be most easily identified from the outside by the channel select switch above the TV output and a vertically mounted modulator (metal box) which can easily be seen through the top grille, just to the right of center.
From the inside
If you are able to open your CoCo 2, it is possible to confirm the board model by looking for REV B on the bottom left corner of the board, somewhat obscured by the keyboard. Also, you should see a 6847 to the left of a vertically mounted RF modulator, a metal box that converts the 6847 output to be viewed on channels 3 or 4.