231-C6D0

Check PWM Cable Connections

Verify all PWM cable connections at TNC control X116-X119 connectors and inverter PWM input terminals are secure and properly seated.

Power down system before checking connections to prevent electrical shock

Test PWM Cable Continuity

Use multimeter to check continuity on PWM cable pins, particularly PWM+, PWM-, and Enable signals between TNC and inverter module.

Check cable routing for pinching or damage near cable carriers and junction boxes

Verify PWM Signal Integrity

Use oscilloscope to measure PWM signal amplitude (typically ±10V) and frequency at inverter input terminals during axis movement attempt.

PWM signals should show clean square waves without excessive noise or voltage drops

Check Inverter Status LEDs

Examine inverter front panel LEDs for fault indicators - red LED typically indicates power stage fault or DC bus undervoltage condition.

Consult inverter manual for specific LED fault code meanings

Measure DC Bus Voltage

Verify DC bus voltage at inverter terminals is within specification (typically 540-750VDC for 400V systems) using appropriate high-voltage meter.

Use proper PPE and high-voltage safety procedures when measuring DC bus voltage

Test Inverter Enable Signal

Check that inverter Enable input receives proper 24VDC signal from TNC safety relay chain and contactor feedback circuits.

Enable signal must be present before power stage can become ready

Check Motor Phase Resistance

Measure motor winding resistance between U-V, V-W, W-U phases to detect shorted windings that could damage inverter power stage.

Disconnect motor cable from inverter before resistance measurements

Verify Motor Type Parameters

Check MP1410.x (Motor type) parameter matches actual connected motor - 0=rotary servo, 1=linear motor, 2=torque motor, 3=spindle motor.

Access via TNC Setup → Machine Parameters → Axes

Validate Motor Electrical Parameters

Confirm MP1420.x (rated current), MP1430.x (rated voltage), and MP1440.x (rated speed) match motor nameplate specifications exactly.

Incorrect current settings can damage motor or inverter

Check PWM Output Assignment

Verify MP1510.x (PWM output number) correctly assigns axis to physical PWM output connector on TNC control module.

PWM outputs typically numbered 0-7 corresponding to X116-X119 connectors

Check TNC System Status

Navigate to TNC Diagnostics → System Status to check for internal hardware fault messages or PWM module communication errors.

Look for red status indicators in hardware diagnostic screens

Test Alternative PWM Output

Temporarily reassign affected axis to unused PWM output channel via MP1510.x parameter to isolate faulty PWM channel.

Document original parameter values before making changes

Verify TNC Power Supply Voltages

Check +24VDC, +15VDC, -15VDC, and +5VDC power supply voltages at TNC control module are within ±5% tolerance.

Low supply voltages can cause PWM output stage malfunctions