The Mitsubishi MR-S series, particularly the MR-S12-100B-E01 model, remains indispensable in many production environments. Despite the series being discontinued and officially unsupported, machines equipped with these drives continue to play a critical role in daily operations.

Challenges of a Discontinued Series

A customer recently delivered several units of this model to us for inspection and repair. Due to the age of these drives, a retrofit was not feasible, as it would significantly exceed the planned budget. The customer explained that he had previously opted for repairs from other service providers, but with inconsistent results: sometimes the units functioned temporarily, only to fail again shortly after.

Initially, this uncertainty was reluctantly accepted—a common scenario given the complexity and age of this technology. However, this was clearly not a sustainable solution.

Common Weak Points and Causes of Failure

The Mitsubishi MR-S12-100B-E01 drives are structurally complex. A particular issue is the electrolytic capacitors, which tend to leak due to age. The electrolyte then spreads across the circuit boards and infiltrates the interior of the drive. Without thorough and professional cleaning, subsequent damages are inevitable.

Typical symptoms of such damage include sudden motor vibrations or even burned-out power supplies—problems that cause expensive production downtime, significantly surpassing the cost of proactive maintenance.

Professional Repair and Preventive Maintenance

The effective solution is a thorough preventive overhaul. At our facility, each drive undergoes a specialized cleaning process designed to fully remove all contaminants, particularly leaked electrolyte. Following this cleaning, each unit is rigorously tested with an original motor and appropriate control systems to ensure complete functionality.

Additionally, the device comprises multiple complex circuit boards and supplementary option boards, adding further functionality. These modules require specialized repair knowledge, not available from every provider.

Conclusion: Why Quality Repairs Pay Off

Our customer’s experience clearly demonstrates that short-term savings on repairs rarely pay off. Especially for older models like the MR-S12-100B-E01, investing in a competent service provider equipped with the necessary technical expertise is beneficial in the long run.

Our Appeal to You:

Do not save money in the wrong place! Have your Mitsubishi drives inspected and proactively maintained by experts. This ensures continuous machine operation, prevents costly downtimes, and safeguards your long-term productivity.

To mentioned Mitsubishi Drive: Mitsubishi Servo Drive MR-S12-100B-E01

More details about our Mitsubishi repair services can be found here:
Mitsubishi drive Repair by Industrypart

We regularly repair including boards:
RG201
RG221
RG221C
RG21B
RF312B
BN624A953G51
BN634A229G51
BN634E230G52

📞 Feel free to contact us with any questions about your Yaskawa drive technology.
Our expert team is happy to help!

Technical Specifications

Number of axes: 2 (integrated axis amplifiers for L-axis and S-axis)
Output power: L-axis: approx. 2 kW; S-axis: approx. 1 kW
Supply voltage: 3-phase 200–220 V AC (±10% to -15%) at 50/60 Hz
Intermediate circuit voltage: approx. 280 V DC
Compatible motors: Mitsubishi AC servo motors HA series (e.g., HA100 for the larger axis, HA80/HA83 for the smaller axis)
Regenerative energy: External braking resistor connectable
Optional cards: No additional card required
Weight: Approx. 5.8 kg

Typical Operating Environment

The MR-S12-100B-E01 servo amplifier is mainly used in CNC machine tools from the late 1980s and 1990s. It is part of the Mitsubishi Meldas servo system and is commonly found in Mazak machines with Mazatrol control systems. This 2-axis amplifier controls feed axes (X, Y, Z or rotational axes) and interfaces closely with CNC controls, translating precise commands into voltage and current pulses to drive servo motors. It is commonly installed in earlier CNC machining centers and turning machines.

Functional Description

The MR-S12-100B-E01 is a fully digital servo amplifier that independently controls two servo axes within one device. Each axis features dedicated power electronics and control circuits. Internal signal processing includes current and velocity control loops, receiving setpoints from the CNC control and comparing them to motor encoder feedback. Safety functions continuously monitor operating conditions, shutting down the unit and displaying error codes if limits are exceeded.

Alarm Codes and Troubleshooting