231-8B30

Check Cable Continuity

Disconnect motor encoder cable and measure continuity of temperature sensor wires (typically pins for PT100/PT1000 sensor) using multimeter.

Ensure axis power is OFF before disconnecting encoder cables

Inspect Cable for Physical Damage

Examine encoder cable along its entire length for kinks, cuts, or damage especially at cable chain entry/exit points and motor connection.

Flex the cable while measuring continuity to detect intermittent breaks

Verify Connector Pin Contact

Clean and inspect encoder connector pins at both motor and control cabinet ends, ensure proper seating and no corrosion on temperature sensor pins.

Replace Encoder Cable

If continuity test fails or physical damage found, replace complete motor encoder cable with Heidenhain specified part number.

Access Motor Parameters

Navigate to MOD function, select 'Machine Parameters', access motor table for affected axis (typically MP7xx series parameters).

Document current parameters before making changes

Verify Temperature Sensor Type

Check motor parameter for temperature sensor type matches actual sensor installed (PT100, PT1000, KTY84, etc.) - typically found in MP7x0 series.

Incorrect sensor type can cause false alarms or inadequate protection

Check Temperature Limit Settings

Verify motor temperature limit parameters are set correctly for the specific motor model - consult motor manufacturer specifications.

Validate Motor Model Parameters

Cross-reference all motor table entries with motor nameplate data and Heidenhain motor database to ensure complete parameter accuracy.

Check Motor Surface Temperature

Use infrared thermometer to measure actual motor housing temperature and compare with normal operating range (typically 40-80°C depending on motor).

Allow motor to cool before handling - hot surfaces can cause burns

Inspect Cooling System

Verify motor cooling fan operation, check air intake filters for blockage, ensure adequate ventilation around motor housing.

Analyze Axis Loading

Review TNC axis load monitoring displays and check for excessive following error, current consumption, or mechanical binding during operation.

Check Mechanical Condition

Manually move axis (with drive disabled) to detect mechanical binding, worn bearings, or excessive friction in the mechanical system.

Measure Sensor Resistance

Disconnect motor and measure temperature sensor resistance at motor terminal box - PT100 should read ~100Ω at 0°C, PT1000 should read ~1000Ω at 0°C.

Use 4-wire measurement method for accurate PT100/PT1000 readings

Test Sensor Response

Apply controlled heat (hair dryer) to motor housing while monitoring sensor resistance - should increase predictably with temperature.

Check Sensor Wiring in Motor

Inspect temperature sensor connections inside motor terminal box for loose connections, corrosion, or damaged wiring.

Replace Temperature Sensor

If sensor readings are erratic or out of specification, replace temperature sensor following motor manufacturer's procedures.

Check TNC Diagnostics

Access TNC diagnostic screens to view raw temperature sensor input values and compare with expected readings for current motor temperature.

Test with Known Good Sensor

Temporarily connect a calibrated PT100/PT1000 simulator or known good sensor to the TNC input to verify input module functionality.

Verify Input Module Status

Check TNC system diagnostics for any reported faults on the analog input modules handling temperature monitoring.

Contact Heidenhain Service

If input module fault is confirmed, contact Heidenhain service for module replacement as this requires factory-level repair.

Do not attempt to repair TNC internal modules - this voids warranty