In this video, we'll guide you through the process of checking some common motor components. We've included the steps below the video so you can follow along. 

As you go, be sure to take clear notes; they’ll be essential if you need to contact our Product Specialists for additional help.

Troubleshooting Motor Components

Before troubleshooting any motor components, first identify the type of motor installed on the machine. Different motor types use different components, so the appropriate troubleshooting steps depend on the motor design.

Step 1: Identify the Motor Type

Determine which of the following motor types the machine uses.

VFD (Variable Frequency Drive) Motor

Typically found on machines with electronic speed control. These motors do not use start capacitors or centrifugal switches.

Proceed to VFD Motor Troubleshooting.

AC Induction Motor

Common on many woodworking and metalworking machines. Depending on the design, these motors may use one or more start/run capacitors and may include a centrifugal switch.

Proceed to AC Motor Troubleshooting.

DC Motor

Typically found on smaller variable speed machines using brushes and electronic speed control. These motors do not use centrifugal switches and generally do not use start capacitors.

Proceed to DC Motor Troubleshooting.

AC Motor Troubleshooting

Capacitor Inspection and Testing

1. Disconnect power by unplugging the machine.
2. Allow the capacitor to discharge by either:
   • Waiting 5 to 10 minutes after disconnecting power, or
   • Carefully discharging the capacitor by shorting the terminals with an insulated screwdriver.
3. Safety: When manually discharging the capacitor, keep your face and body away from the terminals. A spark may occur as the capacitor discharges.
4. Remove the appropriate cover to access the capacitor.
5. Inspect the capacitor for:
   • Bulging
   • Cracks
   • Oil leakage
   • Burn marks
6. Test the capacitor with a multimeter using the capacitance function (preferred) or another approved testing method. Capacitor Inspection and Testing in the video can be found HERE.
7. Replace the capacitor if it is physically damaged or does not test within specification. Use the same microfarad (µF) rating and an equal or higher voltage rating.

Centrifugal Switch Inspection (If Equipped)

Only perform this procedure on motors equipped with a centrifugal switch.

1. Disconnect power.
2. Access the centrifugal switch and contact plate by removing the appropriate motor cover.
   • On many motors, this requires removing the fan cover and cooling fan.
   • Some motor designs are different. On certain models, such as the G0771Z, the centrifugal switch and contact plate are located on the pulley end of the motor instead of the fan end. Refer to the parts diagram or service information for your specific motor if the switch is not located behind the fan.
3. Inspect the contact points for:
   • Burned or welded contacts
   • Excessive pitting
   • Broken springs
   • Mechanical damage
4. Clean minor contact pitting if appropriate, or replace damaged components as necessary.
5. Adjust the centrifugal switch so the contacts just touch, then advance approximately 1/16 inch before tightening.

Test Run

1. Reassemble the motor.
2. Restore power.
3. Verify the motor starts normally and reaches full speed without unusual noises, excessive vibration, or overheating.

VFD Motor Troubleshooting

VFD-controlled motors do not use start capacitors or centrifugal switches.

If a VFD-equipped machine will not start or operates erratically:

1. Verify incoming power to the VFD.
2. Check the VFD display for alarms or fault codes.
3. Record any displayed fault code before cycling power.
4. Inspect wiring between the VFD and motor for loose or damaged connections.
5. Follow the troubleshooting procedure for the specific VFD fault code before replacing components.

DC Motor Troubleshooting

DC motors do not use centrifugal switches and generally do not use start capacitors.

When troubleshooting a DC motor:

1. Disconnect power.
2. Inspect the motor brushes (if equipped) for wear or damage.
3. Check the commutator for excessive wear, burning, or contamination.
4. Inspect wiring and speed control connections.
5. Verify the speed controller is receiving the correct input voltage.
6. Replace worn brushes or damaged components as needed.