1201

Power Down and Access Drive

Turn off main power, wait 5 minutes for capacitor discharge, then remove the electrical cabinet door to access the servo drive modules.

High voltage present - verify power off with multimeter before proceeding

Visual Fan Inspection

Locate the affected axis drive (check alarm history for specific axis). Inspect the internal cooling fan for physical damage, debris, or seized rotor.

Use a flashlight to check for oil leakage from fan bearings or accumulated debris on fan blades

Manual Fan Test

With power off, gently spin the fan blade by hand. It should rotate freely with slight resistance. Binding or grinding indicates bearing failure.

A healthy fan will coast for 2-3 seconds when spun manually

Replace Drive Fan Assembly

Order Haas part number for the specific drive model. Disconnect fan connector, remove mounting screws, and install new fan with proper orientation for airflow direction.

Check Fan Operation

With power on (cabinet door open), observe if the drive fan is physically spinning. If fan runs but alarm persists, suspect tachometer circuit failure.

Keep hands and tools away from moving fan blades

Inspect Fan Connector

Power down system and check the fan connector on the drive for loose pins, corrosion, or damaged wires. The tachometer signal is typically on pins 2-3 of the fan connector.

Use dielectric grease on connector pins when reassembling to prevent corrosion

Measure Tachometer Signal

With fan running, use oscilloscope to measure AC voltage across tachometer pins. Should see 2-5VAC square wave at fan frequency (typically 50-100Hz).

No signal indicates failed tachometer; erratic signal suggests loose connection

Replace Fan or Drive Module

If tachometer circuit in fan has failed, replace entire fan assembly. If drive's tachometer input circuit is damaged, drive module replacement required.

Inspect Air Filters

Check electrical cabinet air intake filters for clogging. Replace filters if visibly dirty or airflow is restricted through cabinet ventilation.

Hold filter up to light source - if you can't see through it clearly, replace it

Clean Drive Heat Sinks

Use compressed air to blow out accumulated dust from drive heat sink fins and fan intake areas. Work from inside cabinet outward to avoid pushing debris deeper.

Use low pressure air (30 PSI max) to avoid damaging electronic components

Check Cabinet Temperature

Verify electrical cabinet ambient temperature is below 104°F (40°C). Check that cabinet cooling fans are operational and cabinet doors seal properly.

Use infrared thermometer to check drive heat sink temperatures - should be <140°F during operation

Verify Ventilation Clearance

Ensure minimum 6-inch clearance around electrical cabinet for proper airflow. Check that cabinet is not installed in direct sunlight or near heat sources.

Check Drive LED Status

Observe the servo drive status LEDs. Red or flashing LEDs may indicate power supply issues affecting fan operation before the 1201 alarm triggers.

Consult the drive label for LED status code meanings specific to your drive model

Measure DC Bus Voltage

Using appropriate safety procedures, measure DC bus voltage at drive terminals. Should read 325VDC ±10% for 240V input systems.

High voltage measurement - use proper PPE and follow lockout/tagout procedures

Check Input Power Quality

Verify incoming AC voltage to drive is within ±10% of nominal. Check for voltage imbalance between phases (should be <2% difference).

Use power quality analyzer to check for harmonics or voltage spikes that can affect drive operation

Inspect Power Connections

Check all power connections to the drive for tightness, corrosion, or overheating. Loose connections can cause voltage drops affecting fan operation.

Perform Drive Self-Test

Access drive diagnostics through NGC control (if available) or drive-specific diagnostic procedures to check internal fault status and fan monitoring circuit.

Some drives have internal diagnostic modes accessible via jumper settings or button sequences

Swap Drive Test

If multiple identical drives are present, swap the suspect drive with a known good unit to isolate whether fault follows the drive or remains with the axis.

Ensure drives are identical part numbers and parameter settings are transferred

Check Drive Firmware

Verify drive firmware version is current and compatible with NGC control version. Outdated firmware may have fan monitoring bugs.

Document current parameters before firmware updates in case restoration is needed

Replace Drive Module

If internal drive fault is confirmed, replace the servo drive module with identical Haas part number. Transfer parameter settings and perform axis calibration.