Howdy,

I have Mach3 (on a dedicated non-internet computer) talking to a C11T via a USB SmoothStepper. Things were fine for a good while but I recently noticed that my spindle speed began to be inconsistent. I hadn't really made any changes that I can remember to possibly cause this. I now replaced the dedicated 12V power supply that is feeding the C11T's 0-10v spindle speed control with a better one because I was previously using a crappy 12v wall wart. But that wasn't the problem. If I start the spindle in Mach at 75% of max, I get the expected 7.5v out of the C11T but the voltage drops down by varying amounts (I guess about 1v on average?) and I hear the spindle speed wandering as a result. It'll go back up to 7.5v at some points but mostly it's wandering between 6v and 7.5v.

Any advice on how to proceed? (I'll also post this question in the CNC4PC forum in case it's breakout board related.)

Thanks in advance,
Tom