80

Power down and lockout machine

Turn main disconnect OFF and follow lockout/tagout procedures before opening control cabinet.

High voltage present in control cabinet - ensure proper lockout procedures

Locate temperature sensor cable

Open control cabinet and locate the temperature sensor cable, typically a small 2-wire connection near the I/O board or mounted on cabinet wall.

Sensor is usually mounted on the back wall of the cabinet away from heat sources

Inspect cable connections

Check both ends of sensor cable for loose connections, corrosion, or physical damage. Verify secure connection at I/O board terminal strip.

Use contact cleaner on corroded terminals before reconnecting

Test continuity

Using multimeter, check continuity through sensor cable and measure sensor resistance (typically 10K ohm thermistor at room temperature).

Access diagnostics screen

Navigate to CURRENT COMMANDS > DIAGNOSTICS and look for temperature sensor input status to verify sensor reading.

Normal cabinet temperature should read between 20-40°C depending on ambient conditions

Measure sensor resistance

Disconnect sensor wires and measure resistance across thermistor. At 25°C, resistance should be approximately 10K ohms.

Ensure cabinet is powered down before disconnecting sensor wires

Perform temperature test

If sensor shows continuity, gently warm sensor with heat gun while monitoring resistance - it should decrease smoothly as temperature increases.

Replace sensor if faulty

Install new thermistor sensor in same location, ensuring proper mounting away from direct heat sources but in representative air flow.

Verify sensor functionality

First confirm temperature sensor and wiring are good by measuring proper thermistor resistance values.

Always verify sensor before suspecting I/O board to avoid unnecessary replacement

Check I/O board connections

Inspect all connections to I/O board, particularly the temperature sensor input terminals for loose or corroded connections.

Substitute known good sensor

Temporarily connect a known good thermistor to the I/O board temperature input to isolate whether issue is sensor or board.

Replace I/O board if confirmed faulty

If good sensor still triggers alarm, I/O board analog input circuit has failed and board requires replacement by qualified technician.

Check cabinet ventilation

Verify cabinet cooling fans are operating and air filters are clean. Check for blocked ventilation openings.

Cabinet fans should run continuously when machine is powered - listen for fan operation

Monitor ambient temperature

Verify shop ambient temperature is within specification (typically below 40°C/104°F) and cabinet is not in direct sunlight or near heat sources.

Inspect servo drive heat sinks

Check servo drive heat sinks for dust buildup and verify heat sink fans are operating properly.

Allow adequate cool-down time before handling heat sinks

Clean and service cooling system

Clean cabinet air filters, verify fan operation, and ensure proper air flow through cabinet before restarting machine.