Need help wiring in a HY VFD to my machine...!

[12volt]

Hi all,

so I inherited a Bionica 8x4, 2.2kw spindle CNC router when I bought a business.. Its been working great guns for the last couple of years. Recently the VFD popped, I bought a new one, same model.

Matched the wiring, and we can get the spindle to turn on. All good so far.

But we can't get the attached Mach3 PC to alter the speed of the rpm. Which it could before. I've attached a photo that's of the original box wiring i took for reference.

The part that's confusing us...aside from it not working....is that all the googling we do, makes us think there should be at least a third wire going to the top line, and not just the blue 'n brown coming from the control board (which runs to a relay and effectively turns the unit on and off it seems) so we don't understand how MACH3 was able to control the spindle speed in this set up, and can't find any references to a set up like this to guide us.

Any help?