Fanuc Parts Specialists

T: +49 (0) 7158 984130  /


Fanuc Alarm 401 V Ready Off / DRDY Signal off

The dreaded Fanuc 401 alarm is the bain of many a CNC service engineers more memorable machine faults to deal with. Technically if the power magnetic circuit / electrics powering the drives; mainly the servo amplifier are good, then the servo amplifier could be causing the 401 alarm.

Check the following items and / or conditions:

  • Are the drives / amplifiers powering up at all?
  • Has an emergency stop been canceled?
  • On ALPHA series drives does the last servo drive in the rack have the terminating JX1B fitted ?
  • Any issues with the MCC contact of the PSM, check that sequence also.
  • Has some alarm been issued on the servo, spindle or power supply module ?

Note: 401 dependent on generation of drive or control can be caused by a multitude of issues.

Fanuc Parts Specialist:

If your Fanuc control system displays a 401 alarm then we can help by assiting with diagnosis and the supply of parts or repair of drives, motors and control systems. Further we can supply amplifiers if required.

DNC carries thousands of Fanuc parts in stock ready to ship today:

1 Day Shipping In EU

with UPS / Fedex / DHL

Part Warranty

Offered in the country of usage

100% Secure Checkout

PayPal / MasterCard / Visa