14.06.2026 by Viktor Siebert
Repair of a Yaskawa UAJPEE-08DK2KU Induction Motor after Brake Failure in a Machine Tool
Introduction: A Real Service Case
A customer from the machine tool industry contacted us because of problems with a tool changer that was operating irregularly and occasionally losing its position. The machine was equipped with a Yaskawa UAJPEE-08DK2KU three phase induction motor from the Yaskawa Juspoint III positioning system.
Since the tool changer performs a critical function within the machine, rapid action was required. The motor was removed and sent to our workshop for inspection.
Initial Diagnosis
During the incoming inspection, it became apparent that the motor was heavily contaminated. Oil residue, dust and coolant contamination had accumulated on the housing and connectors over many years.
Electrical testing initially revealed no abnormalities in the motor windings. The insulation values were also within the acceptable range. However, the mechanical inspection revealed increased bearing wear.
Particular attention was drawn to the installed SNB 0.5ZG-01 holding brake. The brake no longer released reliably and showed electrical irregularities.
Actual Root Cause
After complete disassembly, the root cause could be clearly identified:
• Defective brake coil inside the SNB 0.5ZG-01 holding brake
• Brake lining still in good condition
• Electrical fault inside the coil winding
• Age related material fatigue
• Increased bearing wear
• Worn shaft seals
• Aging effects on the encoder
The actual braking mechanism was still mechanically usable. The failure was caused exclusively by the damaged magnetic coil.
Repair Measures
The following work was carried out:
| Measure | Description |
|---|
| Disassembly | Complete motor disassembly |
| Cleaning | Industrial deep cleaning of all components |
| Repainting | Complete housing repainting |
| Brake | Replacement of defective brake coil |
| Bearings | Preventive replacement of all bearings |
| Seals | Replacement of all shaft seals |
| Encoder | Installation of a new encoder |
| Adjustment | Precision encoder alignment |
| Connectors | Cleaning and inspection |
| Final inspection | Electrical and mechanical testing |
Final Testing and Return Shipment
After completion of all repairs, the motor was tested on our test bench.
The new encoder was precisely adjusted to the required reference position. The brake function was then tested under different operating conditions.
After replacement of the coil, the brake function was fully restored. Encoder feedback values were also stable and accurate.
Following a successful endurance test, the motor was approved for shipment back to the customer.
Customer Feedback
“The tool changer is operating reliably again. We were particularly pleased that the entire brake assembly did not have to be replaced and that an economical repair was possible.”
Information about the mentioned Servopack and Servomotor:
More information about our Yaskawa repairs can be found here.
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Technical Specifications
The following specifications are based on the Yaskawa Juspoint III manual. The UAJPEE-08DK2KU is a three phase induction motor specifically designed for the Juspoint III positioning system.
| Specification | Value |
|---|
| Manufacturer | Yaskawa |
| Model | UAJPEE-08DK2KU |
| Motor Type | Three phase AC induction motor |
| Rated Power | 0.75 kW |
| Rated Current | 4.4 A |
| Rated Torque | 3.98 Nm |
| Maximum Torque | 11.06 Nm |
| Rated Speed | 1800 rpm |
| Insulation Class | Class B |
| Encoder | Optical encoder, 1000 pulses/rev |
| Protection Class | IP44 |
| Ambient Temperature | -10 °C to +40 °C |
| Humidity | Maximum 90% RH |
Operating Conditions
| Parameter | Value |
|---|
| Ambient Temperature | -10 °C to +40 °C |
| Humidity | Maximum 90% RH |
| Installation Altitude | Standard industrial environment |
| Application | Machine tools |
| Protection Conditions | Dry industrial environment |
Integration with Other Equipment
The motor operates as part of the Yaskawa Juspoint III positioning system together with the following components:
| Device | Function |
|---|
| Yaskawa Juspoint III | Positioning system |
| Juspeed-F X3000 | Vector inverter |
| Point Module | Positioning controller |
| PLC | Machine control |
| CNC Controller | Machine tool control |
| Optical Encoder | Position feedback |
Functional Description
The UAJPEE-08DK2KU was specifically developed for the Yaskawa Juspoint III positioning system. The system combines a vector inverter, a positioning controller and an encoder. This allows tool changers, magazine axes and pallet changers to be positioned with a precision similar to conventional servo systems.
The motor receives command values from the Point Module. The encoder continuously monitors the actual position. The system supports automatic positioning, homing operations, jog operation and various positioning modes.
The integrated holding brake ensures that the axis remains securely positioned even when power is removed.
Alarm and Error Codes
The following alarms originate from the original Yaskawa Juspoint III documentation.
| Alarm | Error Name | Meaning | Reset | Corrective Action |
|---|
| 0 | Driver Alarm | Inverter fault | Yes | Check inverter |
| 1 | PG Fault | Encoder fault | Yes | Check encoder and wiring |
| 2 | Emergency Stop | Emergency stop activated | Yes | Remove cause |
| 3 | Setup Missing | No setup after power on | Yes | Perform setup |
| 4 | Zero Point LS Error | Reference switch not detected | Yes | Check switch |
| 5 | Zero Return Error | Homing failed | Yes | Check reference sensor |
| 6 | Undefined Station | Invalid station selected | Yes | Check parameters |
| 7 | Operation Mode Error | Invalid operating mode | Yes | Correct mode selection |
| 8 | Offset Setup Error | Offset fault | Yes | Check offset parameters |
| 9 | LS Position Error | Reference switch too close to Z pulse | Yes | Readjust position |
| A | Offset Range Error | Offset outside allowable range | Yes | Adjust parameters |
| b | Backlash Error | Backlash compensation fault | Yes | Correct parameters |
| c | Station Order Error | Station sequence incorrect | Yes | Reconfigure stations |
| d | ABS Memory Error | Absolute memory fault | Yes | Check memory |
Preventive Measures for the Customer
| Measure | Recommendation |
|---|
| Bearings | Inspect every 5 to 8 years |
| Encoder | Monitor signal quality regularly |
| Brake | Measure coil current periodically |
| Seals | Replace during every major overhaul |
| Connectors | Annual visual inspection |
| Cleaning | Remove dust and oil contamination |
| Repainting | Maintain corrosion protection |
Conclusion
This repair case clearly demonstrates that a brake failure is not always caused by worn brake linings. In this case, the brake lining of the SNB 0.5ZG-01 was still fully functional. The root cause was solely a defective brake coil.
By replacing the coil, performing preventive replacement of bearings, seals and encoder, and carrying out precise encoder alignment, the Yaskawa UAJPEE-08DK2KU was fully restored to operational condition.
The machine can now operate reliably again, and the tool changer is able to maintain its position safely and consistently.