Ok, I'm going to guess: Is the "board" the CPU board? ROM Board? etc?
If the same board works in neither Stargate or Robotron, check several things like:
a) battery corrosion
b) it's not a Williams CPU that's not compatible with those games
c) bad crystal
d) low +5 to the chips
e) bad processor
f) bad ribbon cables between the boards
g) bad decoders
etc...