A Yaskawa Servopack of type CACR-SR30SB1AS-Y124 arrived at our workshop in a severely compromised condition. From the very first inspection it became clear that this was not a minor issue. The unit could still be powered on, but it immediately tripped into fault mode as soon as any motor load was applied. The diagnosis was unambiguous: a short circuit in the power transistor module (W-phase) combined with a damaged terminal block. In this state, the drive was completely non-operational and could not be used without major repair.

Initial Findings and Fault Analysis

Upon receipt, the Servopack was subjected to a thorough visual inspection. Thermal damage around the transistor module was clearly visible, and the terminal block showed cracks and discolored contact surfaces. An insulation resistance test confirmed the suspicion: a permanent short circuit existed between output W+ and ground. Furthermore, the driver stages for the power section showed instability, indicating secondary failures in the control circuitry.

Disassembly and Cleaning

After disassembling the defective sections, the device was carefully cleaned. Over years of service, deposits of dust, oil, and fine metallic particles had accumulated on heatsinks and circuit boards. These were removed using compressed air, chemical cleaning agents, and ionization. The boards were also chemically treated to eliminate potential leakage currents and restore surface insulation.

Replacement of Faulty Components

The transistor module of the W-phase was replaced with an original part. The terminal block was renewed to ensure long-term mechanical stability. The control board showed defective driver stages, which were repaired. In addition, the power supply circuitry for the control logic was refurbished to guarantee stable voltages.

Special attention was given to the driver circuits of the power stage. Faulty driver ICs were replaced, solder joints reworked, and transition resistances corrected to restore reliable triggering of the transistors.

Preventive Replacement

For a Servopack of this generation, repair is not limited to the immediate failure. Age-related weak points must also be addressed. Therefore, all electrolytic capacitors were renewed to prevent future failures due to capacity loss. Connectors were cleaned and re-soldered in critical areas. If fitted, the cooling fan was tested and replaced to ensure long-term thermal stability.

Testing and Verification

After the repair, the Servopack underwent extensive testing on our servo drive test bench. It was connected to a reference motor and subjected to a range of load cycles.

The testing process included:

• Functional checks of all input and output signals
• Load testing under continuous operation up to rated power
• Thermal testing at 40 °C ambient temperature
• Signal monitoring of encoder feedback, current consumption, and switching times

In addition, a long-term endurance test was carried out, with the unit running for several hours under constant load. Temperature rise, stability, and protective functions were closely monitored.

Documentation and Quality Assurance

Every repair follows a strict documentation and quality protocol. All measured values, replaced parts, and test results were logged. This allows us to provide the customer with full transparency and guarantees that the repaired unit meets operational standards.

Customer Benefit

By restoring this Yaskawa Servopack, an essential drive of a CNC machine could be saved. The repair not only represented a significant cost saving compared to purchasing a new unit but also avoided the downtime and integration issues that a replacement would have caused. Thanks to the preventive measures implemented, the repaired unit is prepared for long-term reliable service.

To mentioned Yaskawa Drive:Yaskawa CACR-SR30SB1AS-Y124 Servopack

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Yaskawa drive Repair by Industrypart

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Technical Specifications:

Application & Compatible Devices

The Servopack was typically used in CNC machines, industrial robots, and automated manufacturing systems.
Compatible with Yaskawa USAME-, USAFED-, USASEM- and USADED-Servomotors.
Controller interface: ±10V speed reference, early Yaskawa CNC and machine controllers.

Operating conditions:

• Ambient temperature 0–+40 °C (operation), -20–+60 °C (storage)
• Humidity 20–80 %, non-condensing
• Vibration-protected installation inside cabinets

Functional Description

The CACR-SR30SB1AS-Y124 Servopack is an AC servo drive for speed control.
Key functions:

• Converts mains voltage into PWM-controlled drive voltage for the motor.
• Processes incremental encoder signals for speed feedback.
• Provides protection with extensive monitoring (overcurrent, overvoltage, undervoltage, overheating).
• Controls external braking and regenerative resistors.
• LED indicators (MP, P, IN) and 7-segment error display for status and faults.

Special features: very precise speed control down to 1/3000 rated speed, fast response under load changes, robust hybrid IC technology.

Alarm Messages & Troubleshooting

Components