Basically, I just wanted to replace the gear reducer of the mount with synchronous belts. However, the reduction ratio of 4.88 was difficult to obtain. This report cannot be configured in the original electronics. No question of approaching this value, the precision of the pointing and the tracking would have been felt.
So I had to replace the electronics.

I turned to an Astro EQ  which is fully configurable, and designed to work with EQMod .

It accepts all motors provided they have a nominal voltage less than or equal to 12V, with a current per phase less than or equal to 1A (the internal current limitation is adjustable on the motor drivers). The connection to the PC is via USB.

Just one thing that I don't like is the motor outputs on RJ-11 plugs. I prefer Tiny XLRs for this use.