Initial Situation and Fault Description.

The Yaskawa Servopack CACR-5R5-PD1VDS01 was delivered with an unusual fault description. When the mains supply was switched off via R S T, the internal status indicator did not turn off as expected. When the supply was switched on again, the unit consistently reported alarm A.33 during startup. As a result, the machine could no longer be released for operation because the servopack did not initialize correctly and the axis could not be enabled safely.

This behavior already indicated that the issue was not limited to a classic power or supply fault. Instead, it pointed to a problem in the interaction between control logic, internal power supply, and the connected brake electronics. Especially in older CACR servopacks, the brake electronics are closely linked to internal monitoring functions, so deviations in this area can easily trigger follow-up alarms.

Incoming Inspection and Initial Diagnosis

After the incoming inspection, the servopack was first visually examined. The housing and cooling areas showed no external damage, but age-related signs such as dust accumulation in the ventilation areas were visible. The next step was an electrical pre-check on the test bench.

When the mains supply was deliberately switched off via R S T, the behavior described by the customer could be reproduced clearly. The display remained active, indicating faulty discharge behavior or backfeeding within the internal power structure. After switching the supply back on, alarm A.33 appeared immediately. In the context of this servopack, this alarm is associated with a malfunction related to holding and brake functions.

This combination is typical when the brake electronics no longer operate cleanly and residual voltages or implausible signal states feed back into the control logic.

Technical Analysis of the Brake Electronics

In the next step, the servopack was opened and the internal assemblies were systematically inspected. Special attention was given to the brake control assembly, as it supplies the motor brake and controls its timed release and monitoring.

Measurements showed that the brake electronics no longer provided stable switching states. In the powered-down condition, a residual voltage remained that was not discharged within the specified time. When the unit was powered on again, the internal logic interpreted this condition as an incorrect brake release, directly triggering alarm A.33.

The root cause was aged and electrically unstable brake electronics that could no longer reliably perform their defined function. Such effects usually develop gradually and often become visible only after power interruptions or emergency stop events in machine operation.

Repair Measures and Overhaul

The defective brake electronics were completely reconditioned. The repair was not limited to restoring basic functionality but included targeted preventive refurbishment. Age-sensitive components were renewed, contact points were inspected, and the internal voltage paths were stabilized.

After the repair, the servopack was thoroughly cleaned to remove dust and deposits that can cause long-term thermal and electrical issues. The unit was then reassembled and put back into operation on the test bench.

Multiple cycles of power on, power off, and re-energizing were performed. The shutdown behavior was clean, the display switched off correctly, and the startup process was free of alarm messages. The brake electronics once again operated synchronously with the internal control logic, and alarm A.33 no longer occurred.

Final Functional Test

The final functional test included both electrical and logical checks. The servopack was operated under nominal conditions, including multiple brake cycles and simulated power interruptions. All protection and monitoring functions responded as expected.

Particular attention was paid to the timing sequence of brake release, servo enable, and voltage discharge. These sequences are critical for machine safety and were fully restored after the repair.

Conclusion

The Yaskawa CACR-5R5-PD1VDS01 showed a classic age-related failure pattern in which defective brake electronics led to a reproducible alarm A.33. Through targeted diagnosis, professional repair, and preventive overhaul, the servopack was fully restored to reliable operation. This case clearly demonstrates the importance of systematic analysis and in-depth understanding of internal interactions in older drive systems.

Technical Specifications

Application Environment and Typical Uses

The Yaskawa CACR-5R5-PD1VDS01 is typically used in older CNC and special-purpose machines where robust analog servo drive technology is required. Common applications include machine tools, machining centers, packaging machines, and custom-built systems with controlled axes.

The unit is designed for applications requiring precise speed and torque control and reliable control of a motor holding brake.

The typical environment is a control cabinet with forced ventilation. Due to the thermal design, clean cooling paths and sufficient airflow are essential.

Functional Description

The CACR-5R5-PD1VDS01 is an analog-controlled AC servo amplifier designed to drive Yaskawa servo motors with incremental feedback. It provides motor power, processes command signals from the machine control, and evaluates encoder feedback signals.

A key component of the system is the integrated brake electronics. These control the motor holding brake in a defined timing sequence relative to servo enable and monitor correct operation during power on and power off. Faults in this area can directly trigger alarms because safe axis release cannot be guaranteed.

In addition, the servopack includes internal protection functions such as overcurrent, overvoltage, undervoltage, and overtemperature monitoring. These mechanisms ensure the drive is safely shut down under critical conditions.

Alarm Messages and Troubleshooting

Assembly Overview