Testing a servo amplifier with a multimeter

At Industrial Automation Co, we pride ourselves on providing the industrial parts our customers need when they need them. Sometimes, customers are uncertain if their problem is with their motor, drive, or power supply. Often, you can detect a faulty drive with nothing more than a multimeter.

  1. Apply all necessary lock-out procedures before powering down your machine.
  2. Wait 10 minutes after turning off power to dissipate any stored electrical energy before touching the machine.
  3. Disconnect all cables from the drive and remove it from the machine.
  4. Set your multimeter to resistance mode (ohms).
  5. Check the resistance from the ground pin to each of the following: U, V, W, DC+, and DC-. The meter should read OL (overlimit) for all terminals to ground. If there is a short, the drive is faulty and needs repair or replacement.
  6. Set the meter to diode mode. Put the red probe on the negative DC bus (DC-) and the black probe in turn on U, V, and W. You should see a diode drop of 0.4-0.8V and the three readings should all be within 10% of each other. Readings outside that range indicate a bad power module inside the servo drive.
  7. Repeat step 6 but with the black probe on DC+ and the red probe in turn on U, V, and W. Again, all readings should be between 0.4 and 0.8V and within 10% of each other.
  8. Repeat steps 6 but with the red probe on DC+. All readings should be OL (over limit).
  9. Repeat step 7 but with the black probe on DC-. All readings should be OL.

Any readings outside that range indicate a faulty drive. Reach out to us at 877-727-8757 and we will be happy to provide you a quote for repair or replacement.

A drive may still have a fault even if it passes all these tests. If you are having trouble with your equipment, give us a call and our team of engineers will be happy to help.