If it's like mine, the DC was supplied from a massive three phase transformer. The winding would need to be about 100Vac so that you end up with around 140Vdc off load. Here's how I did mine, way back when https://mightyshiz.blogspot.com/2017...an-handle.html I welded the cores back up afterwards with the MIG.

One additional component I bought was the braking module http://shop.cncdrive.com/index.php?productID=260. This allows you to decelerate quickly without risking overvoltage damage to the servo drivers. This clamps the voltage at around 180V. I must admit I haven't ever checked to see if it cuts in on my system but I didn't plan to risk my drivers to find out. One braking module would be enough per system.