01.09.2025 by Viktor Siebert
Yaskawa CACR-SR20BE12G-E Servopack, Technical Analysis and Repair
The Yaskawa CACR-SR20BE12G-E Servopack from a Hurco BMC 40/50/M CNC milling machine arrived in our workshop with the fault description “no function”.
Initial inspection confirmed that the unit was completely dead, no LED indicators, no activity. Once opened, heavy thermal stress marks were visible. The internal power supply had failed, and the transistor module was destroyed. Furthermore, the driver circuitry of the power stage had multiple defects.
This was a complex multi-stage failure. The defective power supply caused chain reactions that damaged both control and power electronics.
Repair process
- Cleaning: Removal of dust, dirt, and residues
- Preventive replacement: Renewal of capacitors, relays, and semiconductors
- Power supply rebuild: Full reconstruction of the internal PSU
- Power stage repair: Replacement of transistor modules and rework of drivers
- Signal verification: Full checklist-based inspection of encoder and control circuits
- Testing: The unit was tested on our Yaskawa system simulator with:
- Thermal load tests under full power
- Repeated start-stop sequences
- Endurance testing over several hours
The Servopack passed all tests and was returned to the customer with a documented test protocol.
Customer benefit
The repair allowed the customer to quickly restore production on their Hurco BMC milling machine without the need for an expensive replacement unit.
Preventive Measures
- Regular cleaning of cooling paths and fans
- Fan replacement every 3–5 years
- Insulation testing of motor cables
- Seal inspection against dust and oil ingress
- Supply voltage and grounding checks
- Continuous temperature monitoring
Conclusion
The Yaskawa CACR-SR20BE12G-E Servopack is a proven and reliable servo drive found in machines such as the Hurco BMC 40/50/M. Even complex multi-stage failures can be successfully repaired with structured processes, extending the lifecycle and reliability of the equipment.
To mentioned Yaskawa Drive: CACR-SR20BE12G-E Servopack von Yaskawa
More details about our Yaskawa repair services can be found here:
Yaskawa drive Repair by Industrypart
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Device Description
| Feature | Value |
|---|
| Model | CACR-SR20BE12G-E |
| Manufacturer | Yaskawa Electric |
| Series | CACR-SR Servopack |
| Input Voltage | 200–230 V AC, 3-phase |
| Frequency | 50/60 Hz |
| Input Current | 12.0 A |
| Output Voltage | 0–230 V AC, 3-phase |
| Output Current | 19.0 A |
| Output Power | 2.0 kW (2.68 HP) |
| Cooling | Forced air cooling |
| Weight | approx. 7–8 kg |
| Type | AC Servo Drive |
Application & Compatible Machines
The Yaskawa CACR-SR20BE12G-E Servopack is used for precise control of AC servo motors in industrial environments. Typical applications include:
- CNC machine tools
- Woodworking machinery
- Packaging systems
- Automated production lines
The repaired unit presented here originated from a Hurco BMC 40/50/M CNC milling machine, where it drives the servo axes with high precision and reliability.
Functional Description
The Servopack provides accurate control of motor speed, torque, and position. It converts incoming mains voltage into controlled output power for the connected servo motor. Key functions include:
- Stable and precise motor supply
- Processing of encoder feedback signals
- Integrated protection functions (overload, overcurrent, overheating, undervoltage)
- Communication with the CNC controller (e.g., Hurco BMC)
Alarm Messages & Troubleshooting
| Alarm | Display | Probable Cause | Corrective Action |
|---|
| A.01 | External current limit error | Fault in external current limit reader | Replace Servopack |
| A.02 | Reference read error | Failure in reference input | Replace Servopack |
| A.10 | Overcurrent/Overheat | Defective transistor module or overheating | Replace Servopack, check fan |
| A.20 | Circuit protector tripped | Protection circuit failure or >55°C | Check cooling, replace Servopack |
| A.30 | Regenerative error | Regenerative resistor disconnected | Inspect/replace resistor |
| A.40 | Overvoltage | Excessive input voltage, faulty regenerative circuit | Check supply voltage, replace unit |
| A.51 | Overspeed | Encoder failure or wrong parameters | Inspect encoder wiring, adjust parameters |
| A.60 | Undervoltage | Input voltage too low, defective diodes | Check mains supply, replace unit |
| A.71 | Instantaneous overload | Sudden overload | Reduce load, adjust parameters |
| A.72 | Continuous overload | Continuous overload or wiring fault | Inspect motor cabling, check load |
Components
| Name | Board designation | Qty |
|---|
| Control board | CACR-SR1B | 1 |
| Power board | CACR-F2TBI-E | 1 |
| Power stage | Transistor module | 1 |