320-07DB

Access MC housing fan location

Power down system and locate the MC housing cooling fan, typically mounted on the servo amplifier cabinet or drive module.

Ensure complete power isolation before accessing electrical enclosures

Inspect fan for physical obstructions

Check for debris, cable interference, or damaged fan blades preventing normal rotation. Manually rotate fan to detect bearing roughness or binding.

Fan should rotate smoothly with minimal resistance when turned by hand

Measure fan electrical continuity

Using multimeter, verify fan motor winding continuity and check for proper voltage supply at fan connector when system is powered.

Typical MC housing fans operate on 24VDC or 230VAC depending on drive configuration

Replace defective fan assembly

Install replacement fan with identical specifications and reconnect feedback cables to restore proper RPM monitoring to the TNC system.

Verify fan operation visually

With system powered, confirm the MC housing fan is actually rotating at normal speed despite the alarm condition.

Maintain safe distance from rotating equipment

Check RPM feedback signal wiring

Inspect feedback sensor cables for damage, loose connections, or corrosion at the fan connector and control input terminals.

RPM feedback signals are typically low-voltage and sensitive to electromagnetic interference

Test feedback sensor output

Using oscilloscope or frequency meter, verify the RPM sensor generates proper pulse signals proportional to fan speed at the TNC input terminals.

Expected signal frequency typically ranges from 50-200 Hz depending on fan speed and sensor configuration

Replace RPM feedback sensor

Install new tachometer or Hall sensor assembly and verify proper signal generation before clearing the alarm condition.

Measure fan supply voltage

Using digital multimeter, check actual voltage at fan motor terminals during operation and compare to nameplate specifications.

Voltage should be within ±10% of rated value for proper fan performance

Check power supply loading

Verify the fan power supply is not overloaded by other consumers and measure ripple voltage to ensure clean DC power delivery.

High ripple voltage can cause erratic fan operation and premature motor failure

Inspect power supply connections

Examine all connections from power supply to fan motor for loose terminals, oxidation, or voltage drop across connection points.

Voltage drop should not exceed 0.5V across any single connection point

Replace or repair power supply

Install replacement power supply unit or repair faulty connections to restore proper voltage delivery to the MC housing fan motor.

Access TNC servo parameters

Navigate to MOD function, select servo parameters, and locate fan monitoring configuration settings in the MC drive parameter set.

Fan parameters are typically found in the thermal monitoring section of servo drive settings

Verify fan RPM threshold settings

Compare programmed minimum RPM values against actual fan specifications and measured operating speed to identify parameter mismatches.

Minimum threshold should be set 10-15% below nominal fan operating RPM

Check fan monitoring enable status

Verify fan monitoring is properly enabled and configured for the correct feedback sensor type (tachometer, Hall sensor, or voltage feedback).

Disabling fan monitoring removes thermal protection and should only be temporary

Update servo parameters

Correct fan monitoring parameters according to installed hardware specifications and save configuration to TNC memory.

Inspect fan and housing cleanliness

Examine fan blades, housing, and air intake/exhaust areas for dust buildup, oil contamination, or debris accumulation affecting airflow.

Use appropriate PPE when cleaning contaminated equipment

Clean fan assembly thoroughly

Remove accumulated contamination using appropriate solvents and cleaning methods without damaging fan balance or electrical components.

Use compressed air at low pressure to avoid damaging fan bearings or electronics

Verify air filter condition

Check and replace cabinet air filters that may be restricting airflow and causing increased back-pressure on the MC housing fan.

Clogged filters can reduce fan efficiency by 30-50% even with normal electrical operation

Test fan performance after cleaning

Restart system and monitor fan RPM to verify cleaning restored proper airflow and eliminated the alarm condition.