[spitfire3287]

Hello to all!
I have had a hard time with my machine. Throughout the past six months it would randomly throw an alarm....

401 SERVO ALARM : X AXIS VRDY OFF
401 SERVO ALARM : Y AXIS VRDY OFF
401 SERVO ALARM : Z AXIS VRDY OFF

.... Everytime it has done all three simultaneously.
It would do it at random spots in the middle of a cycle on various different parts. I would always just reset the alarm and go about my business because it would do it at most once in a 40 hour week.
Now the real problem. It does it on startup. I cannot move it with the handle, or jog. roughly 5 seconds after the controller starts up it throws the 401 in all 3 axis. I have tried P Cancel as it starts up, but to no avail.
Has anyone out there experienced this problem? If so could it be a loose wire? If so Why would it trip all three axis at the same time?I have checked all connection that I think may be the cource of it, but all are tight... The machine is a Chevalier 2443 VMC if it helps any at all..

[Deltic_Engine]

I had similar problems with a Fanuc/GN6Mb but it was because
there was too much of a voltage drop during certain operations
such as when the spindle spools up or down, or when taking
heavy cuts or starting fast rapids.

IF you are handy (and safe) with a voltmeter, check your voltage
on the 3-phase leads coming into the machine.

The voltage on the 3 leads must be within a certain amount
of each other, plus the average reading must match whatever the
power supply on the machine is set for. (240~250, 208, etc.).

If the power being supplied to the machine is marginal because of
the total draw on your tap from the power company, the machine
can sense the voltage drop when the machine is under load and
throw the 401 alarm on all axis.

Sometmes one lead is weak (say, 5 volts lower voltage than the other two).
If this is the case, you can try swapping the leads (several possible combinations)
and test each combination by operating the machine.

I have a 10hp VMC (3-Phase) being powered by a 30hp Rotary Phase Converter off of a 115V Power Input
If you also are using a converter you may have one weak lead
as described above. It is a typical trait for Rotary Converters but
as long as your electronics are not tapping the weak lead and the
converter is large enough (rated 3X the HP) things should be OK.

Make sure all 3 axis are off of the limits when you power up,
otherwise the alarms might persist.

[yanjue]

Verify the emergency stop circuit and all safety device on your machine.

When an emergency condition occur, the controller disable all axis and show you alarm 401.

[avtechmachine]

401 Servo alarm, I think you should make sure the optic cable plug in properly
Ahn Vuong

[DHYSTA]

If your machine's servo drive is 3-axis drive, get one for replacement.. also check alarm history screen, there may be another alarm occured momentarily just before 401..

[spitfire3287]

How do I get the table off of the limits? Z and Y are at zero right now, but without the servos turning on I cant jog anything....

[Deltic_Engine]

On my Fanuc Black-Cap servos, I remove the rear cap
of the servo and there is an allen screw on the end of
the exposed shaft that can be turned.

[spitfire3287]

For anyone who is curious, I found the root of the problem. the "4th/5th axis neglect" button was faulty. Any vibration would make an unnecessary connection and throw the 401 alarm.... Who would have thought?