Project Description

Mitsubishi Servo Motor Repair

Every Mitsubishi servo motor presents a unique set of challenges to determine what issues may be at work, causing servo failure. Servotech’s evaluation process is a meticulous combination of steps that have been accrued from years of experience working on the motors.

In order to properly repair your Mitsubishi servo motor, we need to have a good working relationship with the factory. The ability to obtain original technical data sheets allows us to make effective repairs. Without this information, a motor can only be repaired to the point where it “runs”. Just because a motor “runs” doesn’t mean that it has the proper torque, mechanical tolerances, or feedback accuracy. Using this information allows us to ensure that your motor will perform to its factory specifications in your machine.

Our goal is to give you a Mitsubishi servo motor that is not only repaired but has been refurbished back to like new condition. Our repair procedure adheres to these steps:

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1. Evaluation of Your Mitsubishi Servo Motor

Servotech inspects all electrical and mechanical parts on all Mitsubishi servo motors. During our evaluation, we check for:

  • Bearing fits
  • Encoder drive tab alignment
  • Housing fits
  • Worn output shafts
  • Corroded and/or broken flanges
  • Connector, cable, and solder joint condition
Mitsubishi Servo Motor for RepairRepaired Mitsubishi Servo Motor
A typical Mitsubishi when it arrives in the shop, and then after we service it.

2. Servo Motor Repair

We manufacture or repair any problems found during our evaluation. A common Mitsubishi problem on the HC series motor, is the epoxy that holds the magnets to the rotor breaks down and the magnets slip. Customers will experience a motor that runs away or draws high current. Consequently, we perform the following:

  • Re-epoxy rotor magnets, and realign placement of magnetic poles.
  • Remagnetize rotor magnets that have been weakened from heat.
  • Re-manufacture a new Mitsubishi servo motor front flange using the old flange and factory dimensions.
  • Repair all the windings. Both AC and DC servo motors windings are washed, baked and tested.
  • Repair or replace brush holders and Bake-O-Lite insulation tubes on DC motors.
Mitsubishi Servo Motor OscilloscopeMitsubishi Servo Remagnetization
Oscilloscope printout of the BEMF (Back Electromotive Force) from a Mitsubishi servo motor with bad magnets and readout after remagnetization with proper BEMF.

3. Preliminary Testing

Throughout the assembly process each Mitsubishi servo motor repair will be meggered numerous times. Some of our tests include:

  • Serial encoder alignment
  • Tach generator tests
  • Test to confirm there are no grounded electrical parts in the servo motor (megger test).
  • All AC stators are surge tested to at least 1500 volts.
  • After the baking process DC servo motor armatures go through a bar to bar test. This test will show if there are any shorts or opens in the winding.

4. Servo Motor Assembly

After repair and preliminary testing, Mitsubishi motors are rebuilt. Our assembly process improves the internal motor components and protects the bearings more effectively than the factory. Our assembled motors utilize:

  • High-grade sealed bearings – non-sealed bearings often used in Mitsubishi servo motors fall prey to dirt and grease. Once the races of a bearing are contaminated the bearings degrade quickly. Servotech’s sealed bearings facilitate a much longer bearing, and consequently motor life.
  • Double lip shaft seals- these seals keep coolant from getting to the bearings.
  • All new seals, O-rings, gaskets and connectors – ensure that your Mitsubishi servo motor is protected from liquid contamination.
  • Two-part epoxy coating for an added protection – the same coating used on Navy submarines.

5. Final Testing on Mitsubishi Factory Drives

The final step in the Mitsubishi servo motor repair process is to run your motor on a Mitsubishi drive just like the one in your machine. Mitsubishi is constantly upgrading their encoding language and high resolution encoders.

Servotech continuously upgrades its software to be able to test and run all of the latest motors and feedback devices. This allows us to make sure the entire servo motor repair process was done correctly. It also allows us to run the Mitsubishi servo motors to full load, and test their feedback at the maximum rated speeds dictated by the manufacturer.

Mitsubishi Servo Motor CapacitorTesting MRJ2 Mitsubishi Servo Motor Drive
Servotech has state of the art equipment needed to fix Mitsubishi servo motors. Above is our capacitor discharge magnetizer. Below, an MRJ2 Mitsubishi drive in the Final Test Department.