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Mitsubishi MDS-B-SP-260 Spindle Drive Unit Hauptansicht
03.07.2025 by Viktor Siebert
Signs That Your Spindle Drive Needs Maintenance. Case Mitsubishi MDS-B-SP-260 Spindledrive

Loss of Power: “I can no longer machine heavy parts.”

A long-time customer contacted us with a clear issue: his Mitsubishi MDS-B-SP-260 spindle drive had lost performance over the years. At first, the problem was subtle. But eventually, the machine was no longer able to process heavier workpieces with the usual power and precision—a clear indication that the drive was no longer delivering full output.

First Countermeasures: Program adjustments and reduced feeds

The customer initially tried to compensate by adjusting the machining programs. Feeds were lowered, cycle times were extended, and cutting parameters were softened. This worked for a while—but the performance gap kept growing.

Red Flag: “Overload” errors occurring more and more frequently

Soon, the “Overload” alarm became a daily issue—appearing multiple times per shift. This kind of error typically indicates:

  • Deterioration of power electronics
  • Overload of aging internal components
  • Thermal buildup or fan failure
  • Capacitor degradation

In many cases, it also reflects unstable current regulation—an early warning sign that preventive action is needed before major damage occurs.

Smart Decision: Repair before total failure

Fortunately, the customer made the right decision and contacted us before things got worse. He requested a professional overhaul before the spindle drive caused a full production stop or damaged surrounding equipment like the motor or power supply unit.

Our Preventive Repair Process: Standardized, tested, documented

We’ve developed a structured and proven repair process for MDS-B-SP-260 drives, based on many years of field experience:

Visual Inspection & Analysis

  • Check for visible damage, thermal wear, and signs of previous repairs
  • Review the fault history (if available)
  • Inspect fan function, terminal connections, and interface ports

Electronic Diagnostics & Component Replacement

  • Replace all known wear-prone components—regardless of their current status
  • Exchange of capacitors, relays, IGBT modules, gate drivers, and opto-couplers
  • Cleaning and resealing of heat-conducting surfaces
  • Fan replacement or overhaul

Load Testing on Test Bench

  • Functional testing under 200 V / 3-phase simulated load
  • Simulated real-world operation with overload pulses
  • Temperature, voltage, and current monitored throughout

Final Inspection & Documentation

  • Isolation resistance check, ripple current test, and leak current measurement
  • Full documentation of replaced parts and performed actions
  • Drive serial number logged for traceability

Our Tip: Don’t wait for the next error

Spindle drives like the MDS-B-SP-260 are the heart of your CNC machine. Declining performance or recurring errors are not minor annoyances—they’re your system’s early warning signals. Acting quickly can save downtime, reduce costs, and prevent catastrophic failures.

To mentioned Mitsubishi Drive: Mitsubishi MDS-B-SP-260 Spindle Drive Unit

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

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

Technical Specifications – Mitsubishi MDS-B-SP-260

ParameterSpecification
ModelMDS-B-SP-260
Drive TypeAC Spindle Drive Unit
Rated Output Power26 kW
Input VoltageDC 270–311 V (from power supply unit)
Input Current115 A DC
Input AC (for fan etc.)0.2 A, 1-phase, 200–230 V, 50/60 Hz
Output Current97 A
Output Voltage3-phase, 200 V, 0–833 Hz
CoolingForced air cooling (internal fan)
InstallationPanel mounting in control cabinet
Dimensions (H×W×D)380 × 150 × 300 mm
Weight10.0 kg
Manual ReferenceBNP-B3759B (Specification Manual)
Compatible Power SupplyMDS-B-CV-260 (DC power supply unit, 260 V, 97 A compatible)
Environment (Operation)0–55 °C, 90% RH or less, no condensation, indoor use only
Environment (Storage)−15 to +70 °C, dry, dust-free storage

Alarm and Warning Messages – Mitsubishi MDS-B-SP-260

Alarm No.Abbr.NameDescription
12ME1Memory error 1A checksum or RAM error occurred in the spindle drive control card ROM
13SWESoftware process errorSoftware process did not finish within the set time
17ADEAD errorThe AD converter did not function correctly during initialization
21NS2No signal (spindle encoder)No signal input from spindle encoder or abnormal signal level
23OSEExcessive speed deflectionSpeed command and actual speed deviation exceeded specified limits
31OSOverspeedMotor speed exceeded 115% of the maximum set speed
32PMOCPower module overcurrentCurrent exceeding the set value flowed into the IPM of the drive
34DPCRC errorCRC error occurred in communication data from the NC
35DEData errorNC movement command exceeded limit during position control
36TETransmission errorPeriodic data transmission from NC was interrupted
37PEParameter errorA parameter value exceeding the tolerable range was set
38TP1Protocol error 1Protocol error in NC communication (frame level)
39TP2Protocol error 2Protocol error in NC communication (information level)
40KE1TK unit change errorChangeover signal procedure was incorrect using the TK unit
41KE2TK unit communication errorCommunication with TK unit was incorrect
44CAXEC-axis changeover alarmCoil changeover alarm when using H coil for C-axis control
46OHMMotor overheatOverload or cooling blower stop caused thermal protection to activate
50OLOverloadMotor current exceeded the set overload time constant
52ODExcessive errorPosition tracking error exceeded specified limits in the loop control
5CORFEOrientation feedback errorOrientation pulse value was outside the set range at orientation complete
60–7FRefer to power supply section for related alarms
82NSPPower supply no signalBreakage or misconnection of cable from power supply detected
E1WOLOverload warningMotor current exceeded 80% of detection time constant
E7NCENC emergency stopEmergency stop signal received from the CNC

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