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Okuma MIV02-1-B1 Servo Drive Unit Hauptbild
11.10.2025 by Viktor Siebert
Repair of an Okuma MIV02-1-B1 Nr. 1006-2212 Servo Drive Unit with axis vibration and noise issue

The customer reported:

“When braking, the motor makes a squealing noise. Replacing it with another unit solves the problem. With the MIV02-1-B1, the Z-axis hums on startup until the control shuts down. No alarm appears on the drive.”

During testing, the unit powered up normally but behaved abnormally under load.
As soon as the axis feedback loop became active, strong mechanical resonance appeared.
Such symptoms on Okuma MIV drives typically indicate feedback loop irregularities or gate control malfunctions.

After full disassembly, the following work was carried out:

  • Cleaning of dust, oil, and metal residues from cooling channels
  • Inspection of all boards for discoloration and cold solder joints
  • Measurement of gate signals and comparison to reference data
  • Replacement of aged components in control and power circuits
  • Verification of internal voltages (+5 V, ±12 V, +24 V)

After completion, the unit was tested in a full-axis setup with an OSP U100 controller and BL II motor.
The previous noise and vibration were completely eliminated.
The axis ran smoothly, with stable torque and temperature readings.
After a 6-hour endurance test, the drive was released for customer use.


Preventive Measures for the Customer

  • Clean cooling ducts and fans regularly (every 6 months)
  • Inspect connectors for oil and dust contamination
  • Check Servo Link and encoder cables for bending or wear
  • Perform regular insulation measurements between motor and power lines
  • Replace fans every 2 years
  • Verify grounding and potential equalization when replacing drives
  • Keep a backup of servo parameter files (Servo Data File)

Conclusion

The Okuma MIV series is highly reliable but sensitive to communication or voltage fluctuations.
Regular maintenance and preventive replacement of thermally stressed components help to avoid downtime and costly failures.

Price and Delivery Time for Okuma MIV02-1-B1 Nr. 1006-2212 Servo Drive Unit

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Technical Specifications (Device Data):

ParameterValue
Model designationMIV02-1-B1
Part number1006-2212-028-083
ManufacturerOKUMA Corporation
Device typeAC Servo Drive Unit (MIV Series)
Rated voltage283–325 V DC (supplied by MPS/MPR Power Supply Unit)
Rated currentapprox. 11 A
Output powerapprox. 2 kVA
Control logic voltage+24 V, ±12 V, +5 V
CoolingForced air cooling (top-mounted fan unit)
Weightapprox. 7.5 kg
Dimensions (H×W×D)approx. 330 × 90 × 250 mm
Insulation classB
Protection classIP20
Compatible controllersOKUMA OSP U / E / P / U10 / U100
Manual referenceOkuma Inverter Unit (MIV) Manual 4742-E P-17 ff.

Operating Environment & Compatible Equipment

The MIV02-1-B1 is used in OKUMA CNC machines, typically in combination with OSP U or P controllers.
Typical applications:

  • Axis control in vertical and horizontal machining centers (e.g., MX-45VAE, LB15II, MA-400HA)
  • Operation of VAC or BL servo motors (e.g., VAC II 5/7.5, BL II D series)
  • Communication via Servo Link (optical data transmission)
  • Power supplied through MPS/MPR-35 or 40 Power Supply Units

The drive is designed for ambient temperatures between 0–45 °C and humidity up to 85% RH (non-condensing).


Functional Description

The MIV02-1-B1 is an inverter module used for servo motor control.
It converts the DC voltage from the MPS/MPR power supply into three-phase AC voltage, supplying the motor with precise variable frequency and amplitude.

Control signals are transmitted via the Servo Link system (L and M side).
A 7-segment LED display indicates operation, warnings, and alarm states.
Internal voltages (+24 V, ±12 V, +5 V) are continuously monitored.
The MIV drive performs torque, speed, and position control based on feedback from magnetic or optical encoders.

Key protection features include:

  • Overcurrent, overvoltage, and overtemperature protection
  • Motor and inverter overload protection
  • Watchdog and CPU supervision
  • Communication monitoring (Servo Link, Encoder Link)

Alarm Messages & Troubleshooting

CodeError DescriptionCauseSolution
01Power Supply Unit ErrorVoltage loss or power supply failureCheck input voltage, replace MPS/MPR unit if necessary
03DC Bus Voltage ErrorDC bus voltage too high or too lowCheck supply voltage, replace MIV or MPS/MPR unit
04Motor Power Line OvercurrentOvercurrent in motor circuitInspect motor and inverter for short circuit
05Inverter OverheatInverter temperature too highCheck fan and ambient cooling
06Inverter OverloadLoad exceeds specificationReduce cutting torque, check MIV condition
10Encoder Communication ErrorEncoder communication failureCheck encoder cable and connectors
12Encoder Initialization ErrorEncoder initialization failedReplace encoder or communication cable
17Magnetic Encoder ErrorSignal fault from magnetic encoderCheck encoder or cable, verify Servo Data File
20Motor OverheatExcessive temperature at motor or encoderCheck thermal sensor and cooling airflow
21Servo Link Communication ErrorCommunication failure with NCInspect Servo Link cable and FCP board
28DIFF OverExcessive position deviationInspect mechanics, test MIV and motor
32Speed Deviation Too LargeDeviation between commanded and actual speedCheck load torque, replace MIV if required
33Collision DetectionAxis collision or mechanical blockageCheck mechanics, adjust NC torque limiter
34Emergency Stop Time OverMachine failed to stop within preset timeCheck braking parameters and servo data file

Components

AssemblyDesignation / CodeFunction
Control boardICB1 / E4809-770-107-F / 1006-2101Central logic and communication control
Power boardIVPB02Power transistor and PWM stage
Connection boardE4809-045-209ALinks control and power sections
Power moduleMIV0303Main inverter module, energy and current path

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