SRVO-135

Identify the affected amplifier

Check the alarm detail on the teach pendant: Press MENU → ALARM → F1 [TYPE] → select SERVO. The alarm will indicate which axis amplifier is affected (e.g., Axis 1, Axis 2). Note the axis number and corresponding amplifier location in the cabinet.

The alarm history may show if this alarm occurred previously on the same axis, indicating progressive fan deterioration rather than sudden failure.

Power down and access the servo amplifier

Perform proper lockout/tagout procedures. Power off the controller completely and wait 5 minutes for capacitors to discharge (10 minutes for high-power amplifiers). Open the cabinet and locate the amplifier corresponding to the faulted axis. Amplifiers are typically labeled with axis numbers on the front panel.

High voltage remains present inside servo amplifiers even after main power is off. Wait the full discharge time and verify with a multimeter before touching internal components.

Inspect the internal fan operation

Locate the internal cooling fan, typically mounted on the side or rear of the amplifier module. Visually inspect for physical damage or debris. Attempt to manually rotate the fan blades with a non-conductive tool. If the fan does not spin freely or feels rough, the bearing has likely failed.

Some amplifiers have multiple fans. The FSAL alarm specifically refers to the control circuit fan (usually smaller) versus the power module fan which may trigger different alarms.

Verify fan electrical connection

Check the fan motor power connector for proper seating. The fan typically connects to the amplifier PCB via a 2-pin or 3-pin connector (3rd pin is tachometer feedback). Inspect connector pins for corrosion or damage. Verify continuity of the fan motor windings if accessible (typically 50-200 ohms resistance).

If the connector has three wires, the third wire provides tachometer feedback to the amplifier. A broken tach wire will trigger the alarm even if the fan is actually spinning.

Replace the fan motor or amplifier

Order the correct replacement fan from Fanuc (provide amplifier model number from the label). If the fan is user-replaceable, install the new fan ensuring correct polarity. If the fan is integrated into the amplifier assembly, the entire amplifier must be replaced. After replacement, power up and verify the alarm clears and the fan runs normally.

Most R-30iA/R-30iB βSV/αSV amplifiers use standard 40mm or 60mm 24VDC fans that can be cross-referenced, but using genuine Fanuc parts ensures proper tachometer signal compatibility.

Perform visual inspection of air pathways

With power off and proper lockout applied, examine the amplifier's cooling vents and fan area. Look for dust buildup, plastic bags, wire ties, or other debris. Check both the intake (typically bottom or side) and exhaust (typically top) pathways for blockages.

In dirty manufacturing environments (grinding, cutting, composite materials), amplifier fans can become completely clogged in 6-12 months without proper cabinet filtration.

Clean the fan and air pathways

Use compressed air (regulated to 30 PSI or less) to blow out dust from the fan area and vents. Hold the fan blades stationary while blowing to prevent over-spinning the motor. Use a soft brush for stubborn accumulation. Ensure no debris falls into other cabinet components.

Never spin fans rapidly with compressed air as this can generate voltage back into the amplifier circuitry and damage sensitive components. Always hold the fan stationary during cleaning.

Check cabinet filtration system

Inspect the main cabinet air filters (typically located at the bottom of the cabinet). Clogged cabinet filters reduce overall airflow and increase internal temperature, putting additional stress on amplifier fans. Replace filters if visibly dirty or per maintenance schedule (typically every 3-6 months).

Upgrading to higher-quality pleated filters or adding a positive pressure purge system can significantly extend amplifier fan life in harsh environments.

Test fan operation after cleaning

Power up the system and verify the fan spins freely without obstruction. The alarm should clear if blockage was the only issue. Monitor amplifier temperature through the servo monitor: MENU → NEXT → SYSTEM → F1 [TYPE] → SERVO. Check temperature readings remain within normal range (typically below 50°C).

If the alarm clears but recurs within weeks, the environment requires more frequent maintenance or improved cabinet sealing and filtration.

Measure fan motor supply voltage

With power on and proper safety precautions, use a multimeter to measure DC voltage at the fan motor connector on the amplifier PCB (typically 24VDC). If voltage is absent or significantly low (below 22VDC), the amplifier's internal fan power supply has failed.

High voltage AC and DC bus voltages are present inside the amplifier. Only measure at the clearly identified fan connector pins. Do not probe other areas of the amplifier without proper training.