SV0603 Spindle IPM Alarm fault in Fanuc drive

SV0603 Spindle IPM Alarm fault in Fanuc drive

Description

SV0603 is the Spindle equivalent of the SV0449 servo alarm. It indicates that the Intelligent Power Module (IPM) for the spindle drive has detected an internal fault. The Spindle IPM handles much higher currents than servo IPMs. The fault protects the hardware from "Shoot-through" (short circuit) or thermal destruction. It appears as "Alarm 12" or "Alarm 8, 9, A" on the spindle drive LED display depending on the model.

Cause

• Spindle Motor Short: The spindle motor windings are shorted to ground due to coolant ingress (very common in milled heads).
• Regen Circuit Failure: The braking energy from the high-inertia spindle could not be dissipated, causing a voltage spike that tripped the IPM protection.
• Drive Failure: The IPM transistor module itself has exploded or degraded.

Solution

1. Megger the Motor: Disconnect the U, V, W cables from the spindle drive. Use a megohmmeter to test the motor insulation. A reading below 50 Megohms is suspicious; below 1 Megohm is a failure.
2. Power Up Empty: With the motor cables disconnected, power on the machine. If SV0603 appears immediately, the Spindle Amplifier is dead.
3. Check Cycle: If it only happens during heavy deceleration, check the regen resistor connections and parameters related to braking.