07.09.2025 by Viktor Siebert

We received two identical Yaskawa SGMGH-03A5A-SE16 motors from a machining center both had failed simultaneously. These motors are part of the former Siemens-Yaskawa venture and have not been supplied by OEMs for several years. For customers, this often creates a critical bottleneck situation.

Both motors showed encoder errors and bearing failures. The breakdown occurred during production, resulting in machine downtime.

Typical Damage Patterns

• Oil and coolant ingress into the motor housing
• Defective encoder signals (sporadic errors, later complete failure)
• Bearing noise and stiffness
• Corrosion on connectors

Repair Process

1. Disassembly and thorough cleaning of housing and windings.
2. Bearing replacement using high-quality sealed precision bearings.
3. Replacement of seals and connectors to prevent future coolant ingress.
4. Oven drying of windings to remove residual moisture.
5. Encoder replacement (UTSAH-B17BE) including programming and fine adjustment.
6. Signal inspection on the Star Ecas20 test bench, checking torque, speed, and feedback signals.
7. Full load testing under operating conditions, following strict checklists (insulation, signal quality, noise, temperature).

After the repair and testing, both motors were successfully reintegrated into the machine factory-level tested and ready for production again.

ormation about the mentioned Servopack and Servomotor:

• Yaskawa AC Servo Motor SGMGH-03A5A-SE16
• Encoder Yaskawa UTSAH-B17BE

More information about our Yaskawa repairs can be found here.

📞 Feel free to contact us if you have any questions regarding your Yaskawa drive technology. Our experienced team is always ready to assist you.

Technical Specifications

Parameter	Value
Motor Type	Yaskawa SGMGH-03A5A-SE16
Power Output	300 W
Rated Torque	1.96 Nm
Rated Speed	1500 rpm
Rated Current	2.6 A
Rated Voltage	200 V AC
Frequency	50/60 Hz
Insulation Class	F
Protection Rating	IP65 (with properly mounted seals)
Weight	approx. 3.5 kg
Encoder	Yaskawa UTSAH-B17BE (absolute)
Manufacturer	Yaskawa Electric, Japan

Application Environment & Compatible Devices

The motor is typically used in CNC machining centers and special-purpose machines, particularly in tool changers, feed axes, and precision positioning tasks.
It is compatible with Yaskawa SGDH (Sigma II) and SGDV (Sigma V) servo drives.
Due to its design origin from the former Siemens-Yaskawa venture, these motors are no longer supplied as new OEM parts, making repairs the only reliable and sustainable solution for customers.

---

Functional Description

The SGMGH-03A5A-SE16 is a precision AC servo motor designed for dynamic motion control.
Together with the UTSAH-B17BE absolute encoder, it provides high-resolution position feedback for demanding applications that require accuracy, repeatability, and reliability.

---

Components

Component	Description
Rotor	Permanent magnet rotor, designed for high dynamics
Stator	Three-phase winding, Class F insulation
Encoder	UTSAH-B17BE absolute encoder
Bearings	Precision ball bearings, grease-lubricated
Housing	Aluminum die-cast with protective coating
Connectors	Power and encoder connectors, oil-resistant
Seals	Radial seals against oil/coolant ingress
Brake (optional)	Depending on motor variant

Alarm Messages & Troubleshooting (Sigma II relevant)

Alarm Code	Alarm Name	Description / Cause	Corrective Action
A.02	Parameter Breakdown	Abnormal EEPROM data in amplifier	Reset parameters, replace amplifier if persistent
A.03	Main Circuit Encoder Error	Power circuit detection abnormal	Inspect main circuit, repair amplifier
A.05	Motor/Amplifier Combination Error	Servo motor and amplifier capacities mismatch	Use correct motor-amplifier pair
A.10	Overcurrent / Heat Sink Overheated	Excessive current through IGBT or heat sink overheating	Check load, cooling, replace power stage if necessary
A.30	Regeneration Error	Faulty regenerative circuit or resistor	Inspect/replace regenerative resistor
A.32	Regenerative Overload	Energy exceeds regenerative resistor capacity	Use correct resistor, adjust deceleration
A.40	Overvoltage	DC bus voltage excessively high	Check power input, supply stability
A.41	Undervoltage	DC bus voltage too low	Check power supply, incoming AC
A.51	Overspeed	Motor speed excessively high	Inspect feedback, parameters, load
A.71	Overload (High Load)	Motor operated at torque well above rating for several seconds	Reduce load, check bearings, inspect axis
A.72	Overload (Low Load, continuous)	Motor operated continuously above torque rating	Reduce continuous torque, improve cooling
A.81	Absolute Encoder Backup Error	Backup supply for encoder failed, position data lost	Replace battery/power supply, reinitialize
A.82	Encoder Checksum Error	Abnormal encoder memory checksum	Replace encoder
A.83	Absolute Encoder Battery Error	Low battery voltage for encoder	Replace encoder battery
A.84	Absolute Encoder Data Error	Abnormal absolute position data	Replace encoder, check cabling
A.86	Encoder Overheated	Encoder internal temperature too high	Improve cooling, replace encoder if damaged
A.C8	Absolute Encoder Clear Error	Encoder multi-turn data not cleared/set correctly	Reset/initialize encoder
A.C9	Encoder Communication Error	No communication between drive and encoder	Replace encoder or cable
A.Cb	Encoder Echo-back Error	Encoder communication data mismatch	Replace encoder, check connectors
A.CC	Multi-turn Limit Disagreement	Encoder and amplifier multi-turn data mismatch	Reset/reinitialize encoder