The subject matter of this specification can be embodied in, among other things, a positioning device that includes an actuator assembly configured to actuate an output shaft based on an input signal, and a position sensor assembly. The position sensor assembly includes a position sensor configured to detect a position of an input shaft not directly coupled to the output shaft, a first input receiver configured to receive the input signal, a first output transmitter configured to provide an output signal based on the position of the input shaft, and a second output transmitter configured to provide another output signal indicative of a failure of at least one of the input shaft and the output shaft. A moveable member is coupled to both the output shaft and the input shaft and is configured to alter the positional configuration of the input shaft and to be actuated by the output shaft.