8

Low-voltage of Capacitor Module (ECM)

Fanuc · Alpha i Series AC Servo Motor and Spindle

What does 8 mean?

The voltage across the Capacitor Module of the ECM has dropped below its minimum operating voltage. This can indicate an insufficient charge or a problem with the charge circuit.

Common Causes

  • The voltage across the capacitor module drops below the minimum required for operation.
  • Capacitor module internal failure or degradation.
  • External load drawing excessive current from the module.
  • Battery or power source supplying insufficient voltage.
  • Faulty voltage sensing circuit for the capacitor module.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Measure the voltage across the Capacitor Modules.

  2. 2

    Check the ECM control module's charging circuit and its input power supply.

  3. 3

    Ensure continuous power supply to the ECM is stable.

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Verified technical data. Last updated: March 2026

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Source: Fanuc Alpha i Series AC Servo Motor and Spindle