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.
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