IRB 6400 S4 axis 4 error

    I'm looking for some insight into a problem I am dealing with. I have an ABB 6400 that I have been fighting with for a while now.


    It began with intermittent Joint speed errors(always axis 4, NEVER any other axis). I have suspected the encoder cable and possibly the servo itself for a while now, but it has been suggested to me that the issue could be in the cabinet. Possible overheating, dust, etc. (I even changed the SMB on a suggestion, to no avail)


    Now it has reached the point that the robot is not only throwing axis 4 joint speed errors, but every few times it also looses the rev count for axis 4.


    I am thinking of replacing axis 4 servo and upper arm cable, but I need to make an informed decision.


    Thoughts? Suggestions?

    We had a robot that worked for years... until it was transferred to another building, then it started having position creep on axis 1. Short version - cracked cable. Unfortunately, you have two spots where cables get weak - the base and the "elbow".

    What exact year/model is it?
    On the old 6400 its in 99% the cable chain in the socket of the robot, take of one of the covers and look inside, if there are pieces of cable insulation there, its a new cable harness.
    If you suspect the drive unit, just shut down the controller and switch them (6400 uses the same driveunits in all 3 places) Driveunit A2 is for axis 4/2, so switch nr2 drive from the right with number 1 or 3, A0 is the DC-link and not a drive unit. then you can see if the error has moved with the driveunit or is still on axis 4.

    Best regards.<br />RoboGeek<br />ABB Robot Technician.

    So I replaced to upper arm servo cabling (hell of a job if you've never done one..) even had to solder an I/O cable because we were sent a cable with customer connection (which my robot doesn't have).


    But, after all that, and after reprogramming my subroutines (lost rev counters), I am up and running and have seen absolutely no issue with the axis 4 error I was getting. Side note: once I got the old cable out I could tell it was in bad shape.


    Thanks for the input to all that answered. :beerchug:

    Rev counters "shouldn't" be a big problem to reset - usually if you're within 1/8" (3mm) the machine will go back where it should. Sometimes it takes a couple of tries. If you're doing a fine calibration - all bets are off.

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