U
Energy Supply Stop (ECM)
Fanuc · αi Series AC Servo Motor and Spindle
What does U mean?
A potential difference across a capacitor module is more than 300V, indicating an energy supply issue or abnormal voltage condition.
Repair Steps
- 1
Measure the voltage across the capacitor modules to confirm it exceeds 300V.
- 2
Check the input power supply to the ECM for stable operation.
- 3
Verify the internal charging and discharge circuits of the ECM for proper voltage regulation.
Verified technical data. Last updated: March 2026
Source: Fanuc αi Series AC Servo Motor and Spindle