sudden loss of power - RJ2 controller

    Hello,


    I am facing an odd issue on one of my robots and I would like some feedback.

    One of my production robots, an M710i with RJ2 controller is experiencing loss of power in a really strange manner.

    The power loss happens during production cycles as well as idle times.
    The power loss is not exactly a power loss, the teach pendant goes off, the operator panel LEDs go off and the servo amplifier also, but on the PSU board both PIL (green) and ALM (red) LEDs are active.

    If I use the OFF switch on the operator's panel the ALM led on the PSU switches off and the OFF button seems to work as intended cutting the power to the controller. I can the restart the Controller using the ON button and the system boots up as it normally does. After a time period of 10 to 20 minutes no matter if on production or idle, same thing happens.
    There is no alarm recorded.
    There are no signs of over temperature.
    Both system fans are clean and working on the backplane.

    There are no alarms on the Main CPU board and the system otherwise behaves as intended.

    There is no documented case on the FANUC RJ2 Controller maintenance manual to guide me on propable causes and corrective actions to take.

    I could not find a similar thread no matter how hard I tried the search function and that makes me scared a bit. :smiling_face_with_sunglasses:

    Sounds to me like your power supply is failing.

    That is why you lose power after set time, a winding opens or a solder joint separates from heat then as it cools it re forms itself. By the time you restart it things have cooled and it is all good. Reheats and re-fails. Lather, rinse, repeat.

    Just my thoughts.

    Quote from mortoch

    Sounds to me like your power supply is failing.

    That is why you lose power after set time, a winding opens or a solder joint separates from heat then as it cools it re forms itself. By the time you restart it things have cooled and it is all good. Reheats and re-fails. Lather, rinse, repeat.

    Just my thoughts.

    My thoughts were also along these lines but as these parts cost several hundreds of Euro, I can't order a part and charge my company based on a notch or on the fact that nothing else fits as a failure. There should be a way to diagnose abnormalties on the PSU and nothing is documented.

    Quote from ps0f0r

    There should be a way to diagnose abnormalties on the PSU and nothing is documented.

    That's quite a generalized statement.

    OEM document errors relating to potential hardware issues and recommendations to resolve.

    The scenario your describing appears to be a result of failing, as opposed to an error.

    This is where product knowledge, history and common electrical troubleshooting skills come in.

    Yes, old school I know, but 'tapping small signal relays' to 'un-weld' them still works in some cases.


    Your PSU could be going into an 'overcurrent/overload situation' causing an electronic restart internally.

    Not giving any of the CPU logic a chance to strike up and thus produce error codes to investigate.


    As mortoch and HawkME stated, check the fundamentals first,


    In addition, I would (and I accept no liability by writing it):

    - Disconnect ALL external cables to the cabinet including arm, external IO and external safety.

    - ie the controller with just the power coming in and teach pendant connected and power on.

    - If it doesn't make any difference, then it's local to the controller only and probably a hardware issue.

    - Then the PSU would be my first suspect and result in having to get one.

    - If it strikes up, then sequentially power off, plug external peripherals in and power on.

    - See at which point the scenario occurs, then this will give you an idea where to look next.


    Many times I have come across strange scenarios with PSU restarts on different robots where:

    - A missing/low incoming specific phase.

    - Short circuit somewhere external to the controller that the PSU supplies which is being pulled low.

    - External services, lose cables, damage umbilical's.

    - PSU has internal electronic component failure.

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