401 servo alarm (VRDY OFF), at turn on, Fanuc OM SOLVED

Eveything was OK with machine, until we have moved it from place to place, just for one meter, by hand, carefully, and cleaned (washer) it, also carefully.

Now when I turn it on (main pow, nc control) and i pull out emergency stop, this alarm appears

401 SERVO ALARM: (VRDY OFF)

And I can't get rid of it, I push reset, it appears again, pull in/out EM STOP, alarm appears again.

Machine is not movable (nor in handle mode).
I have tryed to turn it off and on for several times, but no progress.
And on servo amplifiers there is no alarm code, just " - " as not ready.

I have red lot about this alarm, but it could be anything (wires, relays, amplifier, servo brushes, dirty servo.....?)

And read again my first sentance, it may be important for finding solution.

You may have a limit switch that has stuck open or become shorted by the washing process. Look for limit switches on each axis (in both + and - direction). There are frequently TWO limit switches in each direction. One limit switch simply causes an Overtravel (OT) alarm, and you can then jog in the oposite direction to move off the switch. The second switch is an "Extreme" overtravel switch, and it is designed to protect the ballscrews and stop the servo positively if the first switch should fail, or if the CNC should ignore the OT switch. On some machines, that switch is tied to the 24v E-stop circuit, which will simply make the machine come up "NOT READY". Other machines, however, use the 100vac circuit to enable the servo contactors for that same purpose. If your machine is wired like this, and one of these switches was stuck on, filled with water, or otherwise defective, you will get your 401 servo alarm. Also look for damaged cables from these switches to the CNC, and inspect any connectors you may find along these cables. These extreme overtravel switches are usually wired as "normally closed" and are in series, so actuating any one of them breaks the circuit and shuts down all the servos.

Thanks for help, machine was in "middle" position, far from limit switches.

Actually I have just solved the problem :)

Silly me, we have reconected main power input to tramsformer, and one wire (one phase) was not tightened well, and there were just two phases connected.

(nuts)

Thanx :)

Hi all.
I have the same problem: The alarm " 401" appear on screen when power on, I checked all wires, and can not find the reason. Pls. help me to fix this problem.
Thanks

Pls., Pls. help me.

you have to check the power supply for the axis card it has some pines where you can test 25v 10v -25v or something like that maybe you transformator is broken

Dear robertox
Thanks for your reply, but I checked all the wires and voltage, all it are normally( the machine was work fine before). Is there some thing else?
Did you know how to turn on F148.6, it will turn on Y51.2 then show up the procedure.
Thanks

Remove the cap from each axis motors and remove any brush dust (be careful, it's probably toxic!) and inspect/clean the commutator. While you're at it, check the brush length/condition and replace as required.

I was getting persistant 401 errors on my mill and cleaning out the X and Y motors got rid of them almost completely. I still get the occasional 401 error, but I can usually clear it with one off/on cycle and it's probably because I didn't clean out the Z motor (which is buried in the machine casting).

Dear Scirchen
Thanks for your reply, I'll check it tonorow.

Dear skirchen
I checked already, this is AC motor, do you mean I need to check at encoder? But it's have no too. Pls. help me. Do you have servo amplifier manual( it's code AB-1003-O86), if yes, pls. sent it to me( e-mail: [email protected])
Thanks for your time

Namnp2007,

I'm not 100% sure, but I think that AC motors don't have brushes, so my fix isn't going to work for you. There are lot's of things that it could be; do a google search for "fanuc 401" and you will get lots of results. That's where I got the idea to clean out the brushes .

Fanuc is a good source for the manuals (http://www.fanuc.co.jp/en/contact/index.htm). Plus, their tech department is usually very good about debugging problems over the phone, even if you bought the machine used. I once had a tech on the phone for over an hour; I was checking things on the machine while he was feeding me instructions.

Chris Kirchen

Ok, thanks.

Im geeting the same 401 alarms on my clausing lathe 21i-T control. alarm appears on X, Z, and B axis. Machine has AC motors as well and switches are proxy. othing appears to be stuck to them. Any thoughts or ideas on how i can get this alarm off im all ears

Dear hydrospin
Maybe you need to check some out put relay, when power on, you can hear one "click" sound, that indicated the Amplifier start work, at this time, maybe some relay work too( you can find by LED), but in my case, one of them had bad connection, so machine become down and 401 alarm appear.
Hope to help you.

Dear all

I hope that this file may useful

Quote:

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Originally Posted by congchipham

Dear all

I hope that this file may useful

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Dear congchipham
Thanks for your reply, it's more usefull for us

Hello gents,

what parameter i have to change to increase and decrease the spindle RPM i have a Fanuc OT-C control

Hello

I read carefully this topic.
Don't find any solution for my "401 VRDY OFF "

I have a 0m-C controller and this error appear after 5-10 min from power-on even if the axis is not move.
All the voltage 110V and 220V are OK...The ESTOP circuit are ok...I work with machine only for reference, 5min in program and...401...Can you give some ideas for repair.
Thanks!

Dear DannyB.
Maybe your amplifier was mailfuntion, you have to change it for double check.

Would like to add another solution with error code 401 (fanuc 0M).
Before this error make us to feel sick every day for more than year!!!
On the drive are five relays. Three of them are powered on in parallel.
110V Coil of one of them was burn out. We replaced relay with new one (we used different size relay, original is very rare)
And now our Fanuc works as new!!!
Thanks to everyone (and of course google :-))) who wrote their solution!!!

i have 401alarm on fanuc om.with x,y,z axis.with shorting 7 and 13 pin on z drive connectori get 404 no alarm.

Today also same problem I faced. So found MCC circuit was break . So when this alarm will come then emergency circuit & MCC circuit should be check. Thanks.

I too am having 401 alarm on OT control. Usually at power on. I need to hit E stop and the reset and it usually clears. It must be a relay. I can hear something click if it works correctly. Sometimes I have to do it twice.
Today, had it while running a program, everything stopped and 401 on screen. I cleared it the same way. Very odd, it lost tool position and turret changed to different position than called for on program. Lost a boring bar as is wacked the chuck. Everything seems OK. I zero'd the turret and now it seems fine. This is getting scary. My workshift 0 did not change either.
I did replace the large "motherboard" (PCB A20B-1003-0864-R) on the machine a 5 years back for same reason. I haven't had this alarm for years, but back now.

Next time you get this alarm, check the servo amplifiers in the control cabinet for an alarm number on the 7 segment LED. This should help narrow down what the actual problem is.

Can deal with the alarm, cannot deal with turret position changing. I'll try your suggestion.

Powered up yesterday, no issue and ran machine all day. Today I got the 401 alarm at power up. I had the rear cabinet open and was watching the 7 LED. There is also a green LED above and below all the red ones. None of the red ones light up in 401. However, as it goes through power up, the lower is green lights up and stays lit, then you can hear some sort of relay kick in, that's when the upper green LED lights up. But if it goes into 401, the upper lights, but then turns off, as if the relay didn't catch. Upper green goes on, then out. Hit Estop, then reset button, it then clicked in. Both upper and lower green on, no 401. Again, no red LED's on, ever.
I replaced this entire unit with another one from Fanuc, looks like 3-4 years ago. I believe I was having the same issue back then. Now it's back.

So today, 401 at power up. Same result as above. Top green LED lights for a second, then goes out. Hit E stop, then E stop reset, everything is good. Ran machine for 5 hours in a repeat cycle. Found it in a 401 alarm. Opened door and turret is seated as it should be, but in between two stations. This machine does not have that capability, so I reset Estop as I did in powerup, then zero the turret. Doubled checked, it's good to go, for now.
When powering up and checking back of machine 7 LED, when that top one lights, you can hear a relay clicking in. Relay seems to let loose when it goes out. Find it odd I'm having the same issue with different board, but it took 5 years.
Any thoughts, please reply.

Hello good afternoon I have the alarm 401 servo alarm VRDY OFF present in all the axes of x, z, and head 1 and z, x head 2 of my fanuc 18i-T control I would appreciate if someone can guide me to repair this problem

I haven't had any response to my issue, so I'm just dealing with it.

Yours looks more complicated. Maybe entire board, but it's also 18-T control. I have an O-T control. Try calling hardinge, you might get lucky.

NOTHING TO WORRY IS JUST A SIMPLE SOLUTION. CHECK THE CABLES FOR LOOSE CONNECTION. NEXT CHECK CONNECTION FROM TRANSFORMER INSIDE THE MACHINE PANEL. I TOO HAD THE SAME PROBLEM IN TECHNO WASINO JUST SOLVED IT IN 30 MINUTES BY CHECKING ENCODER CABLE AND ALL CONNECTION. I AM DAM SURE THERE WILL BE LOOSE CONNECTION. CHECK AND REPLY ME SIR MY CONTACT NO : +91 82700 08803 STALLIN.R.K