This month’s product spotlight falls on the Mitsubishi MDS Spindle drives, and to be more specific, on MDS-A-SP and MDS-B-SP series, which are offered in sizes starting from 0.4kW and up to 55kW. They offer a number of features that make it easy and effective to use the drives within a system.

An easy to read display allows for quick alarm reading, for troubleshooting and routine monitoring of each unit. The converter, which was conventionally built into the spindle, is now located within the power supply unit. This allows the spindle unit to be smaller in size and also much lighter than older versions.

Through the use of a high-speed CPU, speed response is improved and allows for quick maneuverability. Additionally, spindle parameters can all be loaded from the NC side, thus allowing enhanced operability.

Common Failures – Alarm Codes and Troubleshooting Steps

When it comes to Mitsubishi MDS-A-SP and MDS-B-SP spindle drives, there are quite a few different alarms that can be displayed on the 7-segment display. We will review the most common ones.

Alarm A.32

One of the most frequent alarms on this type of unit is A.32 which refers to an overcurrent flow detected through the power module. One of the first checks that can be done once this alarm occurs is disconnecting the motor leads (U, V, W) from the drive and check each output phase of the drive to the ground for any short in the circuit. If this passes and there is no short between ground and each leg, it can then be attempted to run with the motor disconnected and verify if the A.32 alarm still occurs or if a different alarm comes up. In many cases, if the A.32 reoccurs after disconnecting the motor leads, there is an internal fault that usually requires further evaluation and repair. When this alarm occurs, regardless of the previously mentioned test results, it is always recommended to meg the motor using a megohmmeter which checks the insulation as well as checking the resistance between each phase combination. More details on this can be found here and in the video below.

Alarm A.37

In addition to A.32, another frequently seen alarm is A.37. This distinguishes an initial parameter error and in most cases can be viewed on the control screen, which will designate a parameter number with the alarm code. This designated parameter can be checked in the control unit and verified to be properly set. If not set properly at the time, setting this to the correct value and then power cycling the machine can help alleviate this alarm from the drive. If the parameter is properly set and the unit is not able to be reset to pass that A.37, it has commonly been found that board level components within the unit are faulty and further evaluation or repair is required.

A full list of alarms and error codes can be found here. Please note that certain codes pertain to different units. This is designated by the SV, SP, and CV columns found in the document.

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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