How to Test Servos

Testing a servo motor is important in making sure it is working correctly. Servo motors are most commonly used in control systems that are meant to be automatic, such as cruise control systems in many modern vehicles. Sometimes servo systems do not work correctly and need be tested for problems. This should be done to prevent any damage to the motor which could result in costly repairs.

Instructions

1

Turn off the power to the machine the servo motor is connected to. If this is a car, remove the battery plugs so there is no power running through the vehicle from the battery. Put on a pair of rubber safety gloves in case any sparks occur while working.

2

Test the motor for any system shorts. Check the ground wire of the servo with the mega ohmmeter. Place the positive lead wire from the mega ohmmeter on T1 (phase one) and the negative lead on the ground wire. Repeat this for the T2 and T3 phases, making sure the lead wires are not touching anything else around the motor.

3

Check the reading on the mega ohmmeter. Each measurement should read around 600 to 2,000 mega ohms. Readings much lower or of zero indicate a short in the system.

4

Test the cable for any shorts. Remove the cable from the motor and inspect it for damages. As with anything electrical, connector pins or wires touching together may cause shorts. Distance these pieces by hand if anything is touching.

5

Check to make sure there is an open circuit in the system. Place the ohmmeter between T1 and T2, T2 and T3 and T1 and T3. The measurement on the ohmmeter should read between 0.3 and 2 ohms. A lower reading, or one of zero, indicates a short.

6

Test the motor brushes. Locate the motor brushes by removing the caps from around the motor. These are usually circular items that may be colored. The brushes are located under the square block protected by the caps. Worn brushes should be cleaned using a cloth. Wipe the entire area until clean to remove dirt.

7

Reattach the battery plugs if the servo motor is on a vehicle. Return power to the motor and it is now ready for use.