BZT - A Poor Quality Machine

[JAZZCNC]

How can I adjust the voltage?

You can't without changing the main psu and then this isn't the problem.! If you want to check for piece of mind test the voltage coming out the PSU or going into the drives.
Looking at how crap that machine is I'd guess it will be between 24-36V.

My advise is don't do or change anything untill we see how the drives are setup and how the controller is tuned regards velocity/acceleration.

[fidia]

Ha ha that statement was a brain dump lol. As I said return to vendor is the best way to adjust the voltage or put it on the 380V line for a minute lol