How to Test Stepper Motors

Stepper motors are common in many hobby projects, such as robots and radio-controlled tanks. Through a series of pulses to the motor, a mechanism has the potential to be controlled with great precision. Proper control by the user depends upon properly functioning stepper motors. From the technical perspective, this means that all sets of motor windings must be usable. Ensuring a properly-functioning stepper motor requires a testing process with a minimum of equipment and some basic information specific to that model of stepper motor.

Review the specification sheets. This model-specific documentation will indicate which pin supplies the common voltage for all the windings, and which pins are connected to specific motor windings.

Make sure the stepper motor wiring harness is accessible. If it is already plugged into a driver circuit, then unplug it. Whether the motor is out of the box or removed from a circuit, make sure that all the connector pins are exposed to enable testing the motor windings.

Set up the digital multimeter. Following the directions supplied, then plug in the probe test leads. Turn on the multimeter and select the highest resistance range possible.

Check each set of motor windings. Insert one of the probe test leads into the common voltage pin connector and the other into one of the winding pin connectors. A good motor winding is indicated by a resistance reading of infinity from the digital multimeter display. This usually reads as "OL" for overload. Check all the other windings using this procedure. Remove the probe leads and turn off the multimeter when you are done testing each winding.

Operate the stepper motor with the driver circuit. Plug the stepper motor wiring harness into the receiving connector on the stepper motor driver circuitry. As per the directions supplied with the motor driver, vary the pulse widths over a broad range to verify the stepper motor works. If you need the motor plugged in to continue using it, then leave it connected. Otherwise, disconnect it from the wiring harness to remove it.