This is one of the questions we are most frequently asked. While a bad drive is certainly a possibility, there are several things you can do to insure you are looking in the right place for the root cause of the problem. Line power: Make sure the drive you are running is actually receiving power. The best way to accomplish this is to measure your supply voltage as close as possible to the drive, ideally right at the L1 and L2 terminals. Proper connection of motor: If the motor leads are not connected directly to the drive terminals, any device external to the output of the drive can be a potential suspect. Most DC motors have an armature resistance that is in the 10s of ohms or less. Measure the motor resistance right at the drive and if you measure an open, the problem is not the drive. Check motor relays, plugs, connectors, conduit boxes, etc. Control Signal: Make sure the drive is actually receiving a command signal to make the motor run. If a speed potentiometer is being uses, measure across the CCW terminal and the center terminal to see if you get a linear increase or decreases in the command signal as you very the position of the potentiometer. If an external command signal is being provided, make sure it varies in the way you'd expect. Enable/Inhibit: Some application may use inhibit or enable commands. Make sure the drive is not being commanded to NOT put out motor voltage. Most drives have inhibit terminals and some have RUN/BRK or Enable terminals. Trim pot adjustments: Some adjustments on the drive can cause motor voltage not to be present. The Current Limit/TQ pot when set too far CCW can cause the motor to stall as soon as it demands current. For testing purposes, the TQ can be set full CW to allow for maximum current if needed. The Maximum Speed trim pot if set too far CCW can also cause the motor voltage to be low, and on some drives, non existent. For test purposes, turn the Maximum adjustment to full CW. Input Voltage Selector Switches: While many of our drives have auto ranging power supplies, some of our drive require you setup the drive to accept either 115VAC or 230VAC.