Series Overview:

The Mitsubishi MDS series covers a large array of drive units, starting with the older MDS-A series and working its way up through the MDS-C1 series. Within the MDS series, there are - servo drives, spindle drives, and power supplies; creating a full system apart from the control side of things. Each type of unit comes with a 7-segment display readout for quick and easy troubleshooting and diagnostics when required.  Servo and spindle parameters are loaded in by the NC upon starting up and can be edited through the associated NC screens.

The servo sizing begins at 0.1kW and goes up towards 15kW while coming in a single or dual-axis variant. Utilizing the same feedback interface, the need for individual detector PCBs has been eliminated and streamlined to conserve space and resources.

The spindle sizes start at 0.4kW and go upwards of 55kW, while offered in normal, high-speed, and IPM motor styles. Though most spindle units have the converter and inverter sections within one frame, the MDS series breaks that down and includes the converter in the Power Supply unit while the actual spindle drive focuses on the inverter portion. This allows for smaller overall unit size and conserving of a good amount of space within the electrical cabinet in most cases.

The power supply units start out at 3.7kW and cap out at 37kW; 37kW is only offered from the B series and onward. Unlike the conventional way of each servo and spindle unit having their own independent converter section, this was put into an integrated power supply for the common use between all units in the system. The MDS series offers two types of power supplies, one which regenerates to the line and one which regenerates through a resistor network in order to dissipate excess energy. Due to the nature of resistive regeneration, when this unit (MDS-A/B-CR) is utilized, an AC reactor is not required.

The MDS series does carry on into the MDS-D series, but that isn’t a product which is currently supported through Precision Zone – though we are in the process of being able to offer support on these within the near future. Below you will find a standard wiring diagram for the system along with some common areas of failure with this type of system.

(Standard Connection Diagram)


Common Failures – Alarm Codes and Troubleshooting Steps:

Across the board, a few of the most common alarms that come up on the MDS series of drive units are over current conditions, low/high voltage conditions, and parameter/communication type alarms.

The overcurrent condition, accompanied by a 32 or 3A showing up on the 7-segment display, occurs when an excess amount of current has been detected as flowing through the power module. Most often, this is caused by the failure of the output modules (PTMs), low insulation found in the motor or cable, or some mechanical binding that is preventing smooth movement and a higher load on the motor occurs. Megging of the motor is a good way to check the motor and cable condition in order to ensure the problem has not stemmed from there.

Voltage alarms are accompanied by a 10 on the 7-segment display for under-voltage and a 33 for over-voltage conditions. Verification of incoming voltages is one of the main areas to check for these types of problems.

An alarm code 37 will appear if an initial parameter error occurs. This occurs when the drive can’t load and initialize parameters upon powering of the NC which sends parameters to the drive at power. This can be due to a faulty drive unit unable to interpret the data or a communication error from the NC to the drive that isn’t allowing the data to be transferred. With the 37 code will be a parameter value which points to the parameter currently in question or at fault for the alarm. Verification that it is set correctly can be done first and if all checks well, a cable swap can be done to try and further verify cabling is not an issue.

For additional support or inquiries, feel free to contact us by phone at 800-551-4420 or online through Our free technical support team can assist with any further questions that may arise.