31.03.2025 by Viktor Siebert
Yaskawa SGDH-50AE Servopack: overhaul, assemblies and alarms
The Yaskawa SGDH-50AE Servopack belongs to the Sigma-II series. At industrypart, a complete overhaul of this model involves more than replacing a single failed component: our previous workshop report describes replacing more than 30 components. This article explains the main assemblies, a systematic approach to diagnosis and the meaning of relevant alarm displays. It discusses the overhaul of this model; no specific customer complaint with an individual alarm code is documented for this report.
Technical specifications
| Item | Specification |
|---|
| Manufacturer | Yaskawa |
| Model | SGDH-50AE |
| Series | Sigma II / SGDH |
| Device type | AC servo amplifier / Servopack |
| Power class | 5.0 kW |
| Supply class | Three-phase, 200 V |
Source for model, power and voltage class: Yaskawa, SOLID-SGDH-50AE. These model specifications do not replace checking the nameplate and the particular unit configuration.
Documented assemblies
| Assembly | Designation in the component overview | Quantity |
|---|
| Control board | SGDH-CA30xx | 1 |
| Power board | SGDH-CB50Ax | 1 |
| Capacitor board | Not specified | Not specified |
| Power section | SGDH-50 | 1 |
These designations are taken from the supplied component overview. The character strings “xx” and “x” are retained as provided; they do not establish a particular board revision. Configuration and compatibility must be checked on the individual unit before replacement.
Fault patterns and systematic diagnosis
The original workshop report identifies internal power supply failures, failed output stages and encoder driver faults as possible fault patterns for this model. These areas work together: the internal supply provides operating voltages, the output stage supplies the motor and the encoder signals provide feedback for control. A fault can therefore affect several functions.
| Area | Diagnostic context |
|---|
| Internal power supply | Supply faults can affect control electronics and signal processing. |
| Power output stage | An overcurrent alarm helps narrow the investigation but does not by itself prove a particular component has failed. |
| Encoder and feedback | The encoder, cable, connectors and amplifier interface must be considered together. |
An alarm display is a starting point for troubleshooting. Examination of the equipment is needed to determine whether the cause lies in the Servopack, connected components or operating conditions. The reference below does not describe additional findings on an individual customer unit.
Sigma-II alarm reference: selected relevant alarms
This table paraphrases the meanings in the Sigma II User’s Manual. It is a selection from the supplied document, not a complete list for every firmware and option variant. Display notation, including “b”, “C” and “d”, is retained.
| Display | Meaning from the alarm document, paraphrased |
|---|
| A.02 | Invalid EEPROM parameter data |
| A.03 | Abnormal power-circuit detection data |
| A.04 | Parameter outside its permitted range |
| A.05 | Motor and amplifier capacity mismatch |
| A.10 | IGBT overcurrent; see temperature-related note below |
| A.30 | Regenerative circuit or resistor fault |
| A.32 | Regenerative energy exceeds resistor capacity |
| A.40 | DC bus voltage too high |
| A.41 | DC bus voltage too low |
| A.51 | Motor speed too high |
| A.71 | High-load overload lasting several to several tens of seconds |
| A.72 | Overload during sustained excessive loading |
| A.73 | Dynamic brake resistor overload |
| A.74 | Inrush-current limiting resistor overload due to frequent power cycling |
| A.81 | Absolute encoder supply lost; position data cleared |
| A.82 | Encoder memory checksum error |
| A.83 | Absolute encoder battery voltage low |
| A.84 | Invalid received absolute position data |
| A.85 | Encoder speed too high at power-on |
| A.86 | Encoder overheated |
| A.b1 | Speed reference input A/D converter fault |
| A.b2 | Torque reference input A/D converter fault |
| A.bF | Servo amplifier system fault |
| A.C1 | Uncontrolled motor operation detected |
| A.C8 | Absolute encoder clearing or multi-turn limit setting error |
| A.C9 | Amplifier-to-encoder communication fault |
| A.CA | Invalid encoder parameters |
| A.Cb | Incorrect encoder communication echoback |
| A.CC | Encoder and amplifier multi-turn limits differ |
| A.d0 | Position error exceeds the Pn505 limit |
| A.E7 | Option unit detection error |
| A.F1 | Main power supply phase missing |
| CPF00 / CPF01 | Digital operator-to-amplifier communication error |
Check applicability: for A.10, the document also mentions heat-sink overheating and marks the temperature-related meaning with a 30 W to 1 kW limitation. A.7A carries the same power limitation. This temperature interpretation is therefore not applied unconditionally to the 5.0 kW SGDH-50AE. According to the table, A.-- indicates normal operation, not a fault.
Warnings and configuration-dependent additions
| Display | Context |
|---|
| A.91 | Overload warning preceding A.71 or A.72. |
| A.92 | Warning preceding regenerative overload alarm A.32. |
| A.33 | AC/DC input type does not match the configured mode; available from firmware Ver. F according to the supplement. |
| A.E0 / A.E1 / A.E2 | Option board missing or not responding, timeout or synchronisation/watchdog error; requires the relevant option. |
| A.E5 / A.E6 | MECHATROLINK synchronisation or communication error; configuration-dependent. |
The supplement also covers special cases for linear scales, linear motors and other option boards. It limits A.76 to 22–55 kW amplifiers, so this code is not presented as an alarm for the 5 kW SGDH-50AE. A.94 and A.95 are option-generated warnings. Diagnosis must always use documentation matching the unit, firmware and installed options.
Source: supplied file “Sigma2_Alarms_CompleteList-6.pdf”, Sigma II User’s Manual, Chapter 9, section 9.2.3, pp. 9-41 and 9-42; warnings in section 9.2.4, p. 9-43. Supplement “Sigma II Alarms”, S2_Add_Alarms.doc, dated 30 January 2001, file page 4. The manual extract does not identify its revision.
Repair and preventive overhaul
Our previous SGDH-50AE report describes a complete overhaul involving replacement of more than 30 components, checks of individual functional stages and simulation of load scenarios. The required scope depends on condition, configuration and diagnosis. This does not establish a fixed replacement list for every unit received.
A professional overhaul considers both active faults and the condition of other assemblies. Preventive maintenance can help identify ageing and wear early and reduce unplanned downtime. It cannot establish a fixed extension of service life. Specific measurements, test duration and load profiles for an individual unit are not documented in this report.
Video: SGDH-50AE overhaul
The existing video provides an insight into preventive overhaul at industrypart.
Device views
Yaskawa SGDH-50AE Servopack – device view.
Yaskawa SGDH-50AE Servopack – front view.
Yaskawa SGDH-50AE nameplate.
Repair enquiry for your Yaskawa Servopack
Does your Servopack report a fault or need a preventive overhaul? Send us the full model designation, a nameplate photograph, the alarm display and a description of when the fault occurs. industrypart supports you with diagnosis, repair and preventive overhaul of industrial drive electronics.
Yaskawa SGDH-50AE AC Servopack in our shop
For more information about our repairs of Yaskawa Sigma-II servo amplifiers, visit our Yaskawa Sigma-II repair service page.