Quote Originally Posted by irving2008 View Post
Can you turn down the power supply? Mine goes down to 32 and up to 40v. it could be that back-emf from the motor had damaged the chip by spiking the supply - I'd limit that board to a 30v supply if it has regulators on-board unless they have an additional dropping zener diode in series. On my board you can see spikes of 65v on deceleration, so I have a snubber (basically a 36v zener and a low ohm resistor) across the supply. Another solution, shown in the attached schematic uses a transistor to the same effect...
Hi Irving,

That snubber circuit is very interesting... It's just what I need. I'm running one of those 50V power supplies that Kip found in "unregulated" mode at 43V. My drivers will smoke at 50V, so I'm nervous.
Can you point me towards any online material that would help size the components to dissipate the sort of spikes I'm likely to see?

Sorry to hijack! (maybe Irving's tip will save a few more driver boards... :)

Tom