In case you arent familiar with Dave Rigotti's boards (Hobby CNC), here is a link.
HobbyCNC EZ Driver Board Combo | HobbyCNC
The now discontinued HCNC Pro was my first controller. Still runs well.
The 4th 6 pin connector was probably for expansion of a possible 4th axis. We all think we need it even if we never use it. All it would need was the DB25 for the input and the outputs for the stepper.
Take good pictures of that tach circuit and post it in the electronics section and hope Al the Man responds. He will know if it is possible to interface the signal with your new controller and how.
A lazy man does it twice.
In case you arent familiar with Dave Rigotti's boards (Hobby CNC), here is a link.
HobbyCNC EZ Driver Board Combo | HobbyCNC
The now discontinued HCNC Pro was my first controller. Still runs well.
A lazy man does it twice.