Leadshine Mx3660 shunt regulator query

[JAZZCNC]

Capacitors are the smoothing/shunt circuit and the PSU output you require will determine the Capacitance required.
I think the MX3660 uses 60Vdc drives so you'll not want much more than 50V output and if using 4A motors you'll require aprox 8A output for 3 x motors(65% total amps).
So Transformer with 2 x 18Vac secondarys wired in series and 300Va will give you aprox 50V with 8.3A or if require more amps go with 500Va for just under 14A.
With 300Va you'll get away with 2 x 4700uf-80 or 100V Caps wired in parallel but for the little extra they cost I'd go with 3 x 4700uf to give that bit more smoothing.

25A or 35A Rectifier.