SV6

Disconnect Power Cables

Power down the machine and disconnect the L and M axis motor power cables at the amplifier output terminals (U, V, W). Ensure lockout/tagout procedures are followed.

Label cables before disconnection to avoid mix-ups during reassembly.

Ensure machine is fully powered off and locked out to prevent electrical shock.

Test Insulation Resistance

Using a megohmmeter set to 500VDC, test resistance between each phase (U, V, W) and ground, and between phases. Resistance should be at least 1MΩ; lower values indicate a short.

If resistance is borderline, retest after cleaning connectors to rule out contamination.

Do not use a standard multimeter for this test as it cannot detect high-voltage insulation breakdowns.

Inspect Cable for Damage

Visually inspect the entire length of the cable for cuts, chafing, coolant damage, or pinching in machine panels. Replace the cable if any damage is found.

Check areas near moving parts or sharp edges where cables are most prone to wear.

Wear protective gloves when handling potentially damaged cables to avoid cuts or contamination.

Isolate Motor from Cable

Disconnect the motor power cable at the motor end to test the motor windings directly. Ensure the machine is powered off and locked out.

Take a photo of the connection before disconnection for reference during reassembly.

Verify no residual voltage is present before touching motor terminals.

Test Motor Winding Resistance

Use a megohmmeter at 500VDC to test resistance between each winding phase (U, V, W) and ground, and between phases. Resistance below 1MΩ indicates a short.

Compare results with motor specifications if available to confirm normal resistance values.

Do not apply excessive voltage during testing as it may further damage windings.

Replace or Repair Motor

If a short is confirmed, the motor must be replaced or sent for rewinding by a qualified technician. Document the fault for warranty or maintenance records.

Check for signs of overheating (discoloration or burnt smell) as an indicator of winding failure.

Do not attempt to operate the motor if a short is detected, as it may cause further damage or fire.

Power On Without Motion

Reconnect all cables and power on the machine without commanding any axis motion. Observe if the SV6 alarm triggers immediately.

Monitor the amplifier status LEDs for additional fault codes during power-up.

Ensure emergency stop is accessible in case of unexpected behavior.

Check Amplifier Fault History

Access the CNC diagnostic screen or amplifier fault log to check for related hardware errors or over-current events prior to the SV6 alarm.

Record all fault codes and timestamps for reference when consulting with Fanuc support.

Do not reset alarms repeatedly without addressing the root cause, as it may mask other issues.

Replace Amplifier

If the alarm triggers at power-on and no cable or motor faults are found, the amplifier's output stage is likely failed. Replace the amplifier with a compatible unit and test operation.

Verify the replacement amplifier's firmware matches the original to avoid compatibility issues.

Amplifier replacement should only be performed by trained personnel due to high-voltage risks.

Power Off and Lock Out

Shut down the machine and follow lockout/tagout procedures to ensure safety before manually inspecting the axis.

Double-check that all power sources are disconnected, including auxiliary circuits.

Failure to lock out can result in unexpected machine movement and serious injury.

Manually Move Axis

Attempt to move the L and M axes by hand or with a manual crank (if equipped) to check for excessive resistance, binding, or unusual noise.

Compare resistance to other axes or historical norms to identify abnormal stiffness.

Do not force movement if significant resistance is felt, as it may damage components.

Inspect and Clear Obstruction

Inspect the axis for debris, misaligned components, or damaged bearings. Clear any obstructions and lubricate as per manufacturer specs before retesting.

Check way covers and seals for debris buildup that might not be immediately visible.

Wear protective gear when clearing debris to avoid injury from sharp edges or contaminants.

Disconnect and Inspect Connectors

Power off the machine, lock out, and disconnect motor power cables at both amplifier and motor ends. Visually inspect connectors for contamination, bent pins, or corrosion.

Use a magnifying glass to spot small debris or cracks in connector insulation.

Ensure no power is present before handling connectors to avoid electrical shock.

Clean Connectors

If contamination is found, clean connectors with electrical contact cleaner and a non-abrasive brush. Ensure no residue remains before reconnection.

Use compressed air to remove loose debris before applying cleaner to avoid pushing contaminants deeper.

Do not use water or non-electrical cleaners, as they can cause further damage.

Retest After Reconnection

Reconnect cables securely and power on the machine to test if the alarm persists. If it does, proceed to other potential causes like cable or motor faults.

Torque connector screws to manufacturer specs to ensure a secure connection.

Double-check polarity and pin alignment during reconnection to prevent shorts.