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Power down the machine completely and lock out electrical power per safety procedures.

Always follow LOTO procedures. High voltage present in amplifier circuits.

Inspect all FSSB cable connections at the CNC control, each amplifier input/output, and verify cables are fully seated with locking tabs engaged.

Examine FSSB cables for physical damage, pinching, or excessive bending especially near connectors and cable entry points.

If damage is found, replace the FSSB cable with genuine Fanuc cable of correct length and type, then power up and verify alarm clears.

Check that incoming AC power is present and correct voltage at the amplifier power input terminals using a multimeter.

Verify correct voltage rating (200V or 400V class) before measurements. Lethal voltages present.

Inspect all fuses on the servo amplifier (control fuses and power fuses) and replace any blown fuses with exact same type and rating.

Observe amplifier LED indicators during power-up - verify power LEDs illuminate and check for any fault indication LEDs on the amplifier front panel.

If no LEDs illuminate or fuses blow immediately upon re-power, the amplifier has internal failure and requires replacement or repair.

Note which axis alarm is reported for and verify the amplifier axis address rotary switches match the expected axis number per machine documentation.

Access CNC parameters 1020-1023 (servo axis assignment) and verify the axis configuration matches the physical amplifiers installed.

Incorrect parameter changes can cause machine damage. Record original values before any changes.

Verify parameter 8102 (FSSB device configuration) matches the actual number and type of devices on the FSSB chain.

If a recent amplifier replacement was done, confirm the new amplifier is the correct model and firmware version compatible with the CNC control version.