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  1. #1
    Join Date
    Oct 2012
    Posts
    24

    Fanuc 6T-B alarm 402:servo Alarm

    hi good evening,


    someone have an idea of this kind of alarm? i already skim my manual or machine catalog but i never find this kind of error in alarm list or diagnostic section .. i already googled it in google well, it says 4th axis alarm or overload.. we tried already to change the servo card but still no joy. someone here can point out where is this located this 4th axis?

  2. #2
    Join Date
    Jan 2011
    Posts
    350
    Well what axis are displayed on your screen?

  3. #3
    Join Date
    Aug 2007
    Posts
    793
    most likely a thermal (overload) relay tripped
    usually this relay disposed under velocity control unit
    check mechanics by hand
    see page 38 of maintenance manual

  4. #4
    Join Date
    Oct 2012
    Posts
    24
    @Botha.y- no axis display just like that 402: servo,
    @guhl- ive reset all thermal overload but still no joy... and then thats what ive research in google "402:servo" 3-axis, 4-axis overload signal is on. Refer to diagnostics 722 or 723 for details and unfortunately there is no 722 or 723 in diagnostic manual... and the axis i have here are "X,Z,C,T, 2nd spindle and AC main spindle" but there is a one card that id like to know, one that is mount at the door..above of the relay panel. i want to know what card is..which in my electrical diagram not exist too..

  5. #5
    Join Date
    Aug 2007
    Posts
    793
    what about thermal contact in servo transformer?

  6. #6
    Join Date
    Oct 2012
    Posts
    24
    ok this is what happened now, when i start the machine it just boot and the hydrualic start. the additional problem is i cannot reset the alarm or move any axes due to this 402:servo alarm. when i check all cards, servo amplifier, well all are in Green or go status. and with its thermal contact we reset it all...

  7. #7
    Join Date
    Aug 2007
    Posts
    793
    i don't understand have you fixed yourproblem ot not?

  8. #8
    Join Date
    Oct 2012
    Posts
    24
    no still same problem , i just explained it in my previous post what really happened

  9. #9
    Join Date
    Jan 2011
    Posts
    350
    For Fanuc 6:
    Servo 404
    The READY signal (VARY) of the X, Y or Z axis velocity control does not turn off even though the READY signal (PRDY) of the position control has turned off
    The READY signal (VARY) of velocity control already on even though the READY signal (PRDY) of the position control is off yet at power on condition

    So it's a general stop condition, something stops your main contactor from triggering? Might be the emg stop line is cut somewhere that gives you this alarm, never worked with a 6T but I'm guessing there might be a EMG message that might appear at the bottom of the screen when emg stop is pressed?

  10. #10
    Join Date
    Mar 2005
    Posts
    816
    Believe it should say EMG or *EMG.

    400 series errors are usually servo or amplifier related.

    Middle digit will tell you which axes has the error.

  11. #11
    Join Date
    Aug 2007
    Posts
    793
    Quote Originally Posted by leiryll View Post
    ok this is what happened now, when i start the machine it just boot and the hydrualic start. the additional problem is i cannot reset the alarm or move any axes due to this 402:servo alarm. when i check all cards, servo amplifier, well all are in Green or go status. and with its thermal contact we reset it all...
    I didn't understand meaning of these words in common context and don't understand still, sorry
    you don't need schematics of the machine for this problem, just maintenance manual for Fanuc 6
    when Fanuc 6 says "overload" he means thermal effect of current and this effect forces some thermal contact
    these drives don't calculate I2t, therefore look for manual and then look for contact
    these contacts are in thermal relays, transformers, may be inside the motor

  12. #12
    Join Date
    Feb 2006
    Posts
    58
    If it happens on power on, check the connection between CAV on the master PCB and CN1 on the control PCB. Also double/triple check the contactor on the relay.

    Basically if your contactor is not tripped, it means your cable is loose/broken or your thermal relay needs to be replaced.
    Check the resistance between terminal 51 and 52 on the transformer. That will tell you whether the contactor is closed or not.

    They big question is WHEN did you get the alarm? What was the machine doing right before it alarmed? That'll really help narrowing down where the problem is.

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