How To Tell The Difference Between a Servo Controller and a Servo Drive or Amplifier?

servo amplifier repairs

Have you ever noticed that the terms servo controller, servo drive, and servo amplifier are often used interchangeably?  This can be confusing!

Here is the explanation in very basic terms:

  • Technically, the Servo Drive (also called a Servo Amplifier) provides power to the Servo Motor. The Servo Controller provides the specific command to action. For example: Move 10 feet at a rate of 20 feet per minute. The Servo Amplifier takes that signal and provides the necessary power for the necessary time to accomplish that task. It does this while constantly monitoring the feedback from the Encoder. It has enough onboard control circuitry to interpret control and feedback signals.
  • Here’s where it gets a bit trickier – the Servo Amplifier and Servo Controller are sometimes incorporated into ONE device. This is likely the reason why these two terms get interchanged. Generally, they are independent units – one for control, and one for power and feedback.


anilam servo amplifier repairs

For example, this recently repaired Anilam servo amplifier SA 301A  (Drive) provides power to multiple servo motors (multiple axis).

anilam servo controller repairs

The above Anilam servo amplifer (Drive) is connected to this repaired Anilam controller CC 516F  that provides the commands for each axis used.

Now that we’ve cleared that up, you might have more questions!

What if they get damaged? Are they Repairable?

In this example, both of these units were repairable. Typically, the servo amplifier has a slightly higher repair success rate than the servo controller, but both are often repairable. The controller is more complicated and often contains several levels of OEM proprietary programming. The amplifier, if not catastrophically damaged, has a higher rate of repair success. It is always best to get a qualified industrial electronic repair service to evaluate your damaged servo amplifiers (drives) and servo controllers when considering whether to repair or replace.

Do you have questions or concerns about your servo controller or servo amplifier, or do you think it may need service? If it’s still under warranty, contact your OEM. If it is out of warranty, contact an independent industrial electronic repair center. They should offer free evaluations for your servo controller and, if needed, a free quote for repairs. They should also provide repair reports and a good warranty that covers both parts and labor.

About the Author: ACS Industrial is an independent industrial electronic repair center providing repair services for servo amplifiers and servo controllers of all types and most all manufacturers including Anilam repairs, as well as servo drive repairs, AC/DC drives, VFD drives, servo motors, encoders, printed circuit board repairs, monitors and touchscreens, PLCs, test equipment, and much more. Our customer service team is available to answer your questions and help solve your industrial electronic repair concerns. Legacy equipment can be repaired! RUSH Service is available. You can reach them by calling 800-605-6419