b

Current Control Circuit Malfunction (ECM)

Fanuc · A20B-2101-0390 αi series AC Servo Motor and Spindle

What does b mean?

The circuit responsible for controlling the current within the ECM has malfunctioned. This is a critical internal fault affecting the ECM's ability to manage power flow.

Repair Steps

  1. 1

    Inspect the control board of the ECM for visible damage or component failure.

  2. 2

    Check power supply rails to the current control circuit.

  3. 3

    Consult ECM diagnostics for specific sub-component failures.

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Verified technical data. Last updated: March 2026
Source: Fanuc A20B-2101-0390 αi series AC Servo Motor and Spindle