401 servo alarm (VRDY off) - Page 2


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Thread: 401 servo alarm (VRDY off)

  1. #21
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    If the transformer was bad it would blow more than one fuse.With the power cables disconnected from the relay and the power off close the relay by hand and measure the resistance across the line contacts.Reading should be very low and same for all three.If not toss the relay.
    What does EE stand for in this degree you have?



  2. #22
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    Hi everyone.

    I have the same problem with my machining center. It has a Fanuc 0m control and the 401 servo alarm (VRDY OFF) message comes right at machine startup. I just bought the machine and the seller said there was no alarms before they disconnected the hydraulic unit. After they reconnected the hyd unit, the message appeared. He said that it's probably because theres air in the oil system but I doubt it. Besides I have let all the air out of the oil tubes.

    The machine starts normally but after a few seconds a relay clicks and this message appears. I measured some voltages from the power unit module and found out that the module does not have power because the main relay does not work, uknow the really big one right after the main power switch and transformer that is driven by the power unit itself. I manually pressed the relay so that all the modules had power but it had no effect whatsoever. The same 401 message appears.

    The servo- or the spindle driver's alarm leds are not lid, but the spindle driver has been changed to a re-built one so im not 100% sure if theres some compatibility problems. But the driver is not broken, it is guaranteed, and there was no alarm when the driver was changed, it appeard later.

    Also no axis limits are pressed because none of the axis are close to the ends and I can hear a relay click by pressing emergency button, and the electric charts say the limit switches are serial connected to the emergency button.

    Any ideas, anyone?



  3. #23
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    Hello. I don't know your particular machine but i can tell you that the VRDY alarm means you dont have the 300 volts on the buss power for the drives. The buss power is the large shinny chrome bars that connect between the drives. Your drives are powered by a power supply. Check your power supply for proper voltages in and out and see if you have a power boot up sequence in your manuals so you will know in what order and when things are powered up in the start up sequence.



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    There are full voltage at the power buss when the main relay is manually pressed. But the relay does not connect by itself. But although there are power at all drives, the alarm still appears.



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    Still having the same problem... A couple of professionals have had a look at the machine but so far no progress.

    I've studied the ladder diagrams and tried to find something that would cause the power module not to connect the main relay. So far I've discovered that all the axis limit switches do work but none of them are pressed, spindle gearbox switches work, emergency button works, spindle and gearbox lubrication works, hydraulics work...

    What I would like to know is that does the power module get some kind of information from spindle or axis amplifiers so that this unleading main relay could be a result of some kind of accessory failure or some other fault? If not, the power module has got to be broken because the only input that it gets via a separate cable is the one from emergency button. And i've measured that it works fine.



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    Default Ground

    Improper grounding can also cause this problem. Does this machine have it's own seperate ground or is it grounded with other machines?



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    It has its own ground, it is connected to the main grid via a 5-wire cable, 3 phases, zero and a ground. Also the phases are in correct order, and just in case I've tried to run the machine also with reversed phase order.



  8. #28
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    Have you checked you servos, power supply and spindle amp to make sure all the boards and cable are pushed in (connected) properly?



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    Yes, I have checked all the connections and every single fuse I could find in the machine. I've also opened the power- and spindle module and inspected if there are any black burned spots in the circuit board or swollen capacitors or something unusual. I found none. :/



  10. #30
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    Could someone with similar milling center test their machines that is the main relay supposed to be connected and the power unit supposed to feed voltage to the crome bars, if the spindle amplifier and axis amplifier are completely disconnected from the power unit?

    This would help me a lot because if there should be power feeded from the power unit, despite if the amplifiers are disconnected, it will narrow my problem down to the power unit itself.



  11. #31
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    The machine is now up and running! Turned out there wasn't anything really busted in the machine, the previous owner had just disconnected the rotating a-axis and this machine needs some kind of blind cable or termination resistor or something like that to the connector that used to lead to optional a-axis servo module. And also he had messed with the parameters and hadn't taken backups so we did need an expert to straighten them out. Who knew that the missing axis caused the main relay to not conduct, I was so sure that the power unit was busted.



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    I'm not really having any luck either; same alarm, both 401 & 402 - x axis and z axis. Above those 2 alarms it also says something like - 1000 something monitoring something:3 . Whatever that means??? I was just there helping the Fanuc 210i-T control, get its memory back (this machine is an old Colchester Clausing Lathe w/a Combi control, built back in 1999); who would have known - you can pull the monitor panel out and connect a keyboard and mouse up to it, to help out... Yeah, so I cleared up the memory problem, but it keeps coming up with these alarms. The Polish guy that works it did a thing inside the back cabinet. By turning off the machine like normal, then pull a jumper in the back cabinet and move it over to the off position, then turn the machine back on (only in back -not the front panel on button), and watch the little code display under the jumper. When four zero's come up, push and hold the button above it. Don't let go until the display reads 2200, (the numbers on the display will read like 100, 200, 1000, etc., until it reaches 2200. Then let it go, turn off the machine, (in back again only), then pull back out the jumper and put it in the on position. Then turn on the machine in back, and then in front like normal. This is supposed to clear the alarms....but it hasn't yet for us. He swears by it!! But maybe that 1000 code means something simple, like I was supposed to take the k.b. and m back off and close up the monitor panel first, before the jumper deal. I don't know yet...I'll go back and try it again tomorrow. You wanna try it? If anyone knows anything or tries this jumper switch, and it works, you guys give me a shout back. I'll check this out tomorrow...G'nite

    Last edited by MrPSr5961; 07-20-2010 at 12:05 AM. Reason: Forgot to put the machine type in.


  13. #33
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    401 ALARM is 'normally' caused when the Fanuc CNC isnot getting the 24 V ready signal send via the ESP switch in the PSM



    402 SERVO ALARM: SV CARD NOT EXIST (sounds like the servo card is faulty)

    Attached Thumbnails Attached Thumbnails 401 servo alarm (VRDY off)-fanuc-alarm-401-001-jpg   401 servo alarm (VRDY off)-fanuc-alarm-401-002-jpg  
    ****************************************************************
    *~~Darwinian Man, though well-behaved, At best is only a monkey shaved!~~*
    ****************************************************************
    *__________If you feel inclined to pay for the support you receive__________*
    *______Please give to charity [url]https://www.oxfam.org.au/get-involved/______*[/url]
    ****************************************************************


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    Smile 401 Alarm

    Hi All

    This is my first post on this site but have been browsing a lot.

    We have 6 fanuc robots(CNC) and resntly had same problem and found power supply -15V rail was not working. It is worth check all the voltages on the power supply card against the 0V line.

    Another choice is servo amplifiers have a loop plug in the bottom and small relay contacts inside to tell cpu that amplifiers are okay. We have found this relay to cause errors and bridge out plug.

    Good luck with your efforts



  15. #35
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    Default servo alarm 401

    dear all

    I've got a Kryle VMC 700C and recently encountered problems with the equipment. The first one was 401-VRDY OFF(servo alarm) , the second one was 1023-magazine failed to index and the third one was 1027-powermate Servo alarm. Through these problems the machine can neither be operated and nor can i know from where could get help on how to troubleshoot those problems.

    Please send your suggestions and advices.

    Regards

    Ashley25



  16. #36
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    Ashley,all I can offer is to concentrate on fixing the 401 alarm and you may find the others go away.



  17. #37
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    Quote Originally Posted by gridley51 View Post
    Ashley,all I can offer is to concentrate on fixing the 401 alarm and you may find the others go away.
    To gridley51

    Thanx Gridley, but it appears that the 401 VRDY OFF is intermittent and constantly when the equipment is powered ON, sometimes it appears and the rest of times it doesn't even show up.

    I've tried testing across the pins 1 and 3 of the cx3 connector on the PSM, and as per the maintenance guide, the contact is shorted, which is PSM OK.

    Please advise for further steps as the equipment's been inactive since long resulting in loss of production.

    Regards

    Ashley25



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401 servo alarm (VRDY off)

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