JRK not registering max and min feedback

Hi, I have 2 Pololu Jrk 12v12 USB Motor Controller with Feedback that are not registering feedback when I try to set them up. When I try and calibrate the feedback it seems to register the absolute max and min values as expected and then sets the max and min to the same value bar one point. (the pot has been moved through at least 100 deg) I have checked the pot;s and they are ok sending a variable voltage back when in different position. When I open up the graph and look at the feedback plot it does not move with large movements of the motor arm but if I shake/ vibrate the arm I can just make out a very small amount of movement on the line, not sure if this help to explain anything. The 3rd JRK I have on the rig is working fine, but these two seem to have exactly the same issue.

Help and guidance greatly appreciated


It sounds like there is either a bad connection from the feedback signals to the jrks, or the FB pins on your jrks were damaged in some way.

Can you double check that when you look at the feedback using the plot built into the Jrk Configuration Utility, you have it set to display “Feedback” and not “Scaled feedback”? If it is set to “Feedback” and you do not see it change when your feedback potentiometer moves, can you try measuring the voltage on the FB pin with a multimeter when the feedback potentiometer is at the each extreme?