Q. Do you have a converter that can output the screen from my laptop (from the VGA port) to an arcade 25" Wells Gardner? both inputs on the Wells Gardner monitor are negative if that helps.
A. There's a GBS board but the best bet is to use drivers to simulate 15 khz then get a J-Pac board
Q. Is there any special cabling for this connection?
A. You can either use the soft15k utility to get 15KHZ working, or buy an Arcade VGA video card. Then pipe the VGA video through a J-Pac and it'll be done. Here is a link to the card: http://www.arcadeinfo.de/showthread.php?8170-International-Overview or the Arcade VGA5000 https://www.ultimarc.com/avgainf.html