10.10.2025 by Viktor Siebert
Repair of a Yaskawa SGDH-15AE Servopack with Alarm A.84 Absolute Encoder Data Error
A long-term customer from the machine-building sector reported an axis failure with alarm A.84 “Absolute Encoder Data Error”. The fault occurred intermittently and caused repeated production stops. Since it was unclear whether the issue came from the motor or the drive, both components, the Yaskawa SGDH-15AE Servopack and the SGMPH-15A1A-YR11 servo motor, were sent to us together.
During the incoming inspection, the fault could be reproduced on our in-house Sigma-II test bench. By swapping with a reference unit, the motor was confirmed to be fully functional, which clearly indicated a defect within the Servopack.
After thorough cleaning and visual inspection, the control board was tested and repaired. A preventive overhaul was carried out on the entire unit: all assemblies were checked, thermal interfaces renewed, cooling system cleaned, and the power stage tested.
The repaired Servopack then underwent several test cycles, first unloaded, then under full load with a 1.5 kW test motor. Over several hours of continuous operation, the device remained fully stable. Encoder communication was constant, and no further alarms occurred.
At the customer’s request, the associated servo motor was also overhauled. The bearings showed signs of wear and were replaced, and the encoder was inspected, cleaned, and recalibrated.
After final testing, the entire drive system passed all inspections. The motor and drive combination operated flawlessly again.
Thanks to targeted diagnostics, experience, and preventive maintenance, the customer avoided unnecessary replacement costs and significantly improved long-term reliability.
Preventive Measures for the Customer
- Regular cleaning of the Servopack and its surroundings
- Fan inspection and replacement at fixed intervals
- Check connectors for corrosion and secure fit
- Visual inspection of heatsinks and airflow paths
- Inspect encoder connections during each motor service
- Preventive replacement of capacitors and seals every 5–7 years
Conclusion
This case demonstrates the importance of structured diagnostics and professional test setups.
With systematic analysis and preventive overhaul, a costly device replacement was avoided and system reliability sustainably improved.
Further information such as price and delivery time for:
Yaskawa SGDH-15AE Servopack
More details about our Yaskawa repair expertise can be found here: Yaskawa SIGMA II repairs by Industrypart
Similar models we regularly repair:
SGDH-15AE-OY
to mentioted Servo Motor: Yaskawa SGMPH-15A1A-YR11 Servomotor
Device Data
| Specification | Value |
|---|
| Model | Yaskawa SGDH-15AE |
| Series | Sigma II Servopack |
| Manufacturer | Yaskawa Electric Corporation, Japan |
| AC Input | 3-phase 200–230 V AC ±10 %, 50/60 Hz |
| Input Current | 9.5 A |
| AC Output | 3-phase 0–230 V AC, 0–300 Hz |
| Output Current | 11.6 A |
| Rated Power | 1.5 kW |
| Protection Class | IP1X |
| Operating Ambient Temperature | 0 °C – 55 °C |
| Cooling Method | Air-cooled (with integrated fan) |
| Weight | approx. 2.4 kg |
| Dimensions (H × W × D) | approx. 177 × 90 × 150 mm |
| Approvals | CE, TÜV, UL, cUL |
| Order Number (O/N) | R12432-124-17 |
| Serial Number (S/N) | D0085D3260810017 |
| Country of Origin | Made in Japan |
| Manual Reference | Yaskawa Sigma II User’s Manual (SIEP S800000 54) |
Application Environment & Compatible Equipment
The SGDH-15AE Servopack from Yaskawa’s Sigma II series is widely used in precision CNC machinery, automation systems, and robotics applications.
Typical use cases include machine tools, packaging systems, electronic assembly lines, and automated handling units.
The unit operates reliably within an ambient temperature range of 0–45 °C and 20–80 % relative humidity.
It is compatible with a range of Yaskawa AC servo motors, particularly the SGMPH series, such as the SGMPH-15A1A-YR11 model.
Depending on configuration, the drive supports both Pulse Train and MECHATROLINK communication interfaces for integration into multi-axis CNC or PLC systems.
Alarm Messages & Troubleshooting
| Code | Alarm Description | Cause | Remedy |
|---|
| A.02 | Parameter Breakdown | Faulty EEPROM data | Reinitialize parameters; check control board |
| A.05 | Motor/Amplifier Combination Error | Motor and amplifier capacities do not match | Configure correct motor type |
| A.10 | Overcurrent / Heat Sink Overheat | Overcurrent or cooling issue | Inspect cooling system, test power stage |
| A.30 | Regeneration Error | Regenerative circuit malfunction | Check regenerative resistor and transistor |
| A.32 | Regenerative Overload | Excessive regenerative energy | Replace or test regenerative resistor |
| A.40 | Overvoltage | DC bus voltage too high | Verify input power supply and brake circuit |
| A.41 | Undervoltage | Insufficient DC bus voltage | Check incoming power and connections |
| A.51 | Overspeed | Motor speed exceeded rated limit | Inspect encoder feedback and control signals |
| A.71 | Overload (High Load) | Motor overloaded for several seconds | Inspect axis mechanics; reduce load |
| A.84 | Absolute Encoder Data Error | Invalid data received from encoder | Inspect encoder and cable connection |
| A.C9 | Encoder Communication Error | No signal between motor and amplifier | Check encoder cable, connectors, and feedback circuit |
| A.F1 | Power Line Open Phase | Missing phase in main supply | Inspect input wiring and fuses |
Components
| Assembly | Part Number / Designation | Function |
|---|
| Control Board | DF0200245-D0 Rev.D0 | Signal processing, communication, regulation |
| Power Module | DF0200124-B0 Rev.B0 | IGBT output stage for motor drive |
| Power Supply Section | – | Provides regulated voltages for control and power stages |
| Regenerative Resistor | internal / external | Dissipates energy during braking |
| Heatsink & Fan | – | Thermal dissipation |
| Connection Terminal Block | – | Interface for motor, power, and control connections |