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Diagnosing Servo Motor Issues: Electrical or Mechanical?

Diagnosing Servo Motor Issues: Electrical or Mechanical?

Diagnosing servo motor issues can be challenging, especially when determining whether the issue lies within the electrical system or the mechanical components. Malfunctions lead to production downtime and costly repairs if not diagnosed accurately and promptly. 

Therefore, understanding the distinction between electrical and mechanical issues is essential for prompt and effective troubleshooting.

Servo Motor Electrical Problems

Servo motor circuit board

Electrical issues are often the first suspect when troubleshooting servo motor problems. These problems can stem from various sources, including power supply issues, wiring faults, feedback device failures, or problems within the motor controller.

Here are some common symptoms indicating electrical problems:

No Movement or Erratic Movement

If the servo motor fails to move or exhibits erratic behavior, it could indicate an electrical issue. This may be due to a loss of power, incorrect voltage, or a fault in the wiring connections.


Excessive heat generated by the servo motor can be a sign of electrical problems such as overloading, incorrect current, or a short circuit. Overheating can lead to insulation breakdown and component failure if not addressed promptly.  Some technicians are also surprised to learn that overheating can result from an improperly aligned encoder, even if there are no problems with the motor windings or magnets. A misaligned encoder causes the drive to believe the motor shaft is constantly in the wrong position and produces excessive torque in trying to find the correct position. This video explains this problem in more detail. The problem can be avoided by having certain resources for servo motor encoder alignment:

Fault Codes or Error Messages

Many servo motor systems are equipped with diagnostic features that display fault codes or error messages when electrical issues occur. These messages can provide valuable insights into the nature of the problem, such as overvoltage, undervoltage, or communication errors.

Servo Motor electrical wiring

Intermittent Operation

Intermittent operation, where the servo motor works sporadically or inconsistently, is often indicative of loose connections, faulty wiring, or intermittent power supply issues.

To diagnose electrical problems in a servo motor system, technicians typically perform a series of tests, including voltage measurements, continuity checks, and inspections of wiring connections. They may also use diagnostic tools such as multimeters and oscilloscopes to analyze electrical signals and identify abnormalities.

12 Steps to Reduce Servo Motor Repair Costs

Servo Motor Mechanical Problems

While electrical issues are commonly associated with servo motor problems, mechanical issues can also arise and affect performance. Mechanical problems are largely related to issues with the motor shaft, bearing, or couplings. These components may be dirty, worn,  or damaged causing them to no longer properly function.

Here are some signs of mechanical issues:

Excessive Noise or Vibration

Unusual noises or vibrations emanating from the servo motor can indicate mechanical problems such as worn bearings, misalignment, or mechanical resonance.

Difficulty in Movement

If the servo motor struggles to move smoothly or encounters resistance, it may be due to mechanical issues such as binding, friction, or mechanical overload.

Increased Current Draw

Mechanical problems can increase the load on the servo motor, leading to higher-than-normal current draw. Monitoring the motor’s current consumption can help identify mechanical issues such as binding or excessive friction.

Physical Damage

Visual inspection of the servo motor and its associated components may reveal signs of physical damage, such as bent shafts, cracked casings, or worn gears, indicating potential mechanical issues.

Servo Motor Part

To diagnose mechanical problems in a servo motor system, you may perform visual inspections, conduct mechanical tests such as torque measurements, and check for proper alignment and lubrication of moving parts.

A note of caution: Make sure to record the current alignment of the feedback device before disassembling the motor for a closer inspection of its internal components.

8 Tips for Troubleshooting Servo Motor Problems

Servo Motor Testing

Determining whether a servo motor problem is electrical or mechanical requires a systematic approach. By carefully analyzing symptoms, conducting tests, and inspecting components, technicians can accurately identify the root cause of the issue and take corrective action.

Reliable servo motor diagnosis tools can help quickly determine the root of the problem and confirm or eliminate that the issue lies with the servo motor. We invite you to learn more about servo motor diagnosis solutions from Mitchell Electronics, Inc. and how we can help keep your machines running.