63 ALARM — Auxiliary regeneration error

Check the appearance of the regenerative resistor on the back of the power supply unit. If the resistor is completely clean and no cutting oil, mist, or dust is adhered, the auxiliary regenerative transistor is faulty; replace the power supply unit. If dirt or oil is present, proceed to cleaning and electrical checks.

Turn OFF the main power and wait at least 15 minutes for the capacitors to discharge. Visually inspect the heat dissipating fins at the back of the unit for clogging or contamination by cutting fluid or dust. Clean the fins and the regenerative resistor surface thoroughly.

Using a multimeter, check the electrical continuity between the power supply terminal block (P, N, R, S, T) and the surface of the regenerative resistor. If continuity exists (a short circuit is detected), the internal transistor is permanently damaged. Replace the power supply unit.

If the resistance value from the previous check is infinite (∞) (normal insulation), take protective measures on the machine to prevent cutting oil, mist, or dust from reaching the drive unit's rear heat sink and regenerative resistor.

Restore power to the machine and monitor the operation. If Alarm 63 immediately recurs upon powering ON despite the unit being clean and having infinite resistance to the surface, the internal circuitry of the power supply unit has failed. Replace the power supply unit.

If none of the above steps resolved the alarm, contact authorized Mitsubishi service.