The Yaskawa CACR-SR30BB1AM Servopack arrived with fault code “F” displayed at power-on.
According to the customer, the drive shut down during production and could not restart afterward.

Upon inspection, the DC link voltage measured only 65 V DC far below the normal level. A visual check revealed burned traces in the regeneration section. The high-power resistor (3 kΩ / 300 W) was open, causing uncontrolled feedback and overvoltage stress on the circuit.

Additionally, one of the power transistors showed discoloration and shorted collector-emitter terminals, confirming a severe overcurrent event. The general fault “F” indicated simultaneous protection triggers (overcurrent and overtemperature).

The repair began with complete disassembly, cleaning, and visual inspection of all PCBs.
The following components were replaced as a preventive measure:

• All power transistors and freewheeling diodes
• The regeneration resistor
• The gate driver IC
• All main electrolytic capacitors in the DC bus
• The heat sink temperature sensor
• All connectors and re-soldered joints

After reassembly, the Servopack was tested with a Yaskawa USAFED-30C servo motor. The current control loop operated stably, the protection circuits responded correctly, and the rated no-load speed was reached precisely.

A four-hour endurance test followed, cycling between acceleration and braking up to 2500 rpm. The unit maintained stable operation, the housing temperature stayed below 65 °C, and the LED indicators confirmed normal status.
The repaired drive was shipped with a detailed test report and measured data.

Service and Preventive Recommendations

1. Clean fans and heat sinks every six months.
2. Inspect the regenerative resistor for overheating and tighten terminals.
3. Replace electrolytic capacitors after seven years of operation.
4. When fault “F” appears, first check DC link voltage and then read the 7-segment display.
5. Never exceed 230 V AC line voltage, as it can trigger overvoltage shutdown.

Conclusion

The fault “F” on the Yaskawa CACR-SR30BB1AM indicates a general alarm condition that often involves combined power and control faults.
Through expert refurbishment including replacement of aged components, cleaning, and reconditioning of the regeneration circuit the unit was restored to full working condition.
It now operates fully within Yaskawa’s original factory specifications and is ready for long-term service in industrial environments.

To mentioned Yaskawa Drive: Yaskawa CACR-SR30BB1AM Servopack

More details about our Yaskawa repair services can be found here:
Yaskawa drive Repair by Industrypart

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Technical Specifications:

Application Environment and Compatible Devices

The CACR-SR30BB1AM Servopack was developed for precise speed control in CNC and automation systems. Typical applications include machine tools, turning centers, grinding machines, and industrial robots.
The unit operates with Yaskawa USAFED-30C or USAMED-30B servo motors and, with its 6000-pulse encoder feedback, ensures stable torque control even at low speed ranges.

It is designed for indoor installation, protected from direct sunlight, oil vapor, humidity, and dust. Mounting is done vertically on a control cabinet wall, ensuring proper ventilation (minimum clearance 10 cm above and below).

Functional Description

The CACR-SR30BB1AM Servopack is part of Yaskawa’s M·F·S·D Series and serves as an AC servo amplifier for speed control.
Its internal structure consists of three main sections:

1. Power Stage (Inverter Section):
   PWM-controlled transistor modules convert the 3-phase AC input into variable AC output for the motor.
2. Control Section (Logic Board):
   A microprocessor-based system monitors all protection circuits (overcurrent, overvoltage, temperature, open phase).
   Inputs include reference voltage, servo-on signal (S-ON), and torque limits (P-CL, N-CL).
3. Regenerative Circuit:
   Handles energy feedback during deceleration through a transistor and a high-power resistor.

Communication is achieved through connectors 1CN (signal) and 2CN (encoder).
In the event of a fault, the unit displays codes via the 7-segment LED, while operation status is indicated by green LEDs (MP, P, IN).

Alarm Messages and Troubleshooting

Components