MR-J2 Overview

The Mitsubishi MR-J2 Servo Amplifier Series is suited for use in high-power-rate, ultra-low-inertia, and high-frequency applications. The series comes fully equipped with the latest advanced features, including Mitsubishi’s unique servo lock anti-micro-vibration function, real-time auto-tuning and automatic motor recognition.

Inclusion of an absolute encoder as standard equipment helps to reduce time and enhance reliability by eliminating homing sequence and other sensors. With Mitsubishi’s original absolute mode, an absolute system can be configured using conventional I/O even with pulse-train output control. The MR-J2 comes equipped with a torque control function, users can switch between control modes: position/speed and speed/torque. Micro-vibrations in the servo-lock state are suppressed through a unique method developed by Mitsubishi, providing the construction of stable systems. With real-time auto-tuning, the unit is automatically adjusted to the optimal setting without any need for the gain adjustment unique to servomotors. Model adaptive control provides the realization of a highly responsive and stable system. The MR-J2 comes with RS232C serial communications as a standard feature, enabling users to connect a personal computer using the setup software provided, users can display a variety of monitoring data, perform batch entry and saving of parameters, use graph functions, and perform test operation.  Incorporating motor identification information into the encoder means that the servo amplifier can automatically recognize the drive motor. When the servo amplifier detects a mismatch, an alarm is triggered, eliminating the possibility of an error and the need for setting parameters.

Common Failures

Most common Alarm on Mitsubishi MR-J2 Servo Amplifiers is Alarm 32 Overcurrent. This alarm can be triggered by issues with motor, motor cabling, or issue with the amplifier itself. There are two tests that can be done to isolate the problem, insulation and output section tests.

Testing for weak insulation in the motor and motor cable will require a megger, a standard multimeter will not be able to perform this test. For step by step information on using a megger visit the YouTube link below. Typically motors under 300 Mohms should be sent in for repair.  A standard multimeter may be used to measure the resistance across each pair of legs, U-V, U-W, and V-W. The resistance should be low and the same across each leg.

Even if you Find a problem with the first Test it is highly recommended to test the amplifier output section as in some instance’s amplifiers can be damaged along with the motor. To test the output section, remove Motor U, V, and W Cables with the power off from the amplifier. Next, power up the Amplifier and try to recreate the process that the amplifier alarmed out with alarm 32. If amplifier alarms out with alarm 32 and motor is disconnected there is a bad component and Amplifier will need to be sent in for repair.

At Precision Zone, we guide our clients toward the best decisions that serve their business needs. If you have specific repair or replacement questions, get in touch with our expert customer support team at 800-551-4420 or

Written by:

Marketing & Creative Director at IcarTeam, and supporting afiliated businesses,
including Precision Zone, Precision Education Integrators and Alfra Tools.
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