Talon SRX outputting maximum of 3.5 V

Hey folks,

We are controlling a fairly heavy arm (~15-20 lbs) rotating on a shaft with a 775pro on a VersaPlanetary 40:1 reduction and a Talon SRX. When we started to test it with manual joystick controls, it functioned as expected. However, it stopped moving after a few times moving it from the forward limit switch to the reverse, and after isolating the problem we determined that the SRX would only output a maximum of 3.5 V in either direction.

After replacing it with another SRX and testing it again, we observed the same thing happening after a few successful runs. Our only theory as to why this is happening is back EMF from the arm falling down. We hooked up the leads of the motor to a voltmeter and observed a maximum 4.5V of back EMF.

Has anyone had similar experiences or have solutions for how to fix it (either protecting the Talon or preventing the backdrive when the arm falls down)?

I should also add that the self-test and diagnostics turned up fine on the web dashboard, and the status lights appear as expected