Well, I could throw out a wild guess.... I don't have one of your model, so I don't know if this is correct, or not....
But my thought is that you'd need a sync (blackburst?) on the sync cable, and a TBC'd input on the sync input.
In other words, I might guess that the model you have probably requires a TBC.
Also, I probably wouldn't plug that DB-9 into a joystick port. It may actually be a serial output for controlling said TBC. Of course, it could be some kind of joystick dongle, too. Unless you can scare up some documentation or start checking what signals it outputs, you're kind of going to be stuck. :-(
My white Vidi Amiga 24RT only has standard inputs/outputs, and doesn't require a TBC, and only plugs to the parallel port. :-/
