SRVO-068 DTERR alarm on every axis

    I've got a SRVO-068 DTERR alarm on every axis right now. Group 1 Joints 1-6.


    We're currently in the process of buying a used S430-iw and we are getting it set up in our shop to try it out. We've never used industrial robots before so we're learning as we go.


    It had been sitting for a couple of years before we moved it, so when we first powered it up we got a SRVO-062 BZAL alarm and replaced the batteries. We remastered the robot and then realized that it was facing into the wall so we unplugged all of the cables from the robot, spun it around, and plugged everything back in. When we powered it back up we had all those alarms and we can't even jog the robot.


    We called Fanuc Support and they said to check the RP1 cable which we did several times. Continuity is good between both ends of the cable and we couldn't see any wires disconnected from the back of the giant plug in the robot base.


    We've tried a lot of little adjustments like tightening the shield clamps in the cabinet even though those weren't touched between the robot working and not working. We've tried making sure the cables aren't a rat's nest so there not interference in the pulsecoder cable. And at this point we're all out of ideas.


    Does anybody know what's going on here?

    Welcome to the forum.

    Lets start with something common to all 6 PulseCoders.

    Is this an 'A' style cabinet or 'B' style cabinet?

    Is the controller end of the PulseCoder feedback cable RP1 connected to CRF1 on the servo amp top board?

    If 'B' controller, verify no bent over pins at RP1 connection on base of robot. Could be shorting out the 5VDC power to the PulseCoders.

    Since it happened after moving the robot, also check cables going to J2 & J3 PulseCoders as they sit at the end of those motors where they can easily damaged. If shorting out the 5V, it could effect all 6 PulseCoders as they all use the same 5V.

    I don't know if it's an 'A' style cabinet or 'B' style cabinet. But here's a picture inside and out.





    CRF1 is the large connector in the top left corner of the clear plastic cover, right? If so, I double checked it an it seemed well seated and the error didn't go away after adjusting it.


    There were no obviously loose wires in the back of RP1 in the base of the robot.


    There were no obviously bent pins on the front of the RP1 connector in the base of the robot.


    As a small side note, is RP1 the only one of the four connectors in the robot that isn't asymmetrical and can go in either way? There's a missing pin towards the top right and I've made sure that matched with the missing pin in the cable, but it's possible it went in the wrong way one of the times we were testing it.




    And let me just be sure, the pulsecoder cables are the ones going into the red part on the ends of the motor, right? If so, those weren't even touched when we spun the robot around. Could I pull one of the connectors off and test for 5V there?


    Thanks for the response. You've given me a few extra things to troubleshoot.

    It is a B-style cabinet. Looks like the Control Reliable (RS-1) version used by GM back in the day.

    Normally in a B-cabinet, the robot-to-controller cables went from the base of the robot directly to the servo amp and I/O in the controller.

    The Control Reliable cabinet has the robot-to-controller cables plug into the base of the controller and another internal set makes the connection to the servo amp and I/O. This allowed GM to quickly replace the robot-to-controller cables without opening the controller door. This also adds another connection point at the base of the controller that needs to be verified.

    Before you get too far, try resetting the PulseCoder thru the Master/Cal menu. Search the forum for the procedure. Do you still get the DTERR alarm after a reset of the PulseCoders?

    If so, go ahead and measure the for the 5V at any one of the motor PulseCoder connectors (going to the red cap). Here is the pinout for the connector, it is the same on all 6 motors.


    Thanks for those suggestions. Those were some trouble shooting steps I haven't tried yet.


    I tried resetting the pulsecoders in the Master/Cal and it didn't clear the DTERR alarms.


    I also tried measuring 5 volts on pulsecoder connectors and couldn't find any voltage on the 5V and 0V pins from the pinout, or between any other pins for what it's worth.


    I guess that means it's shorting. I see if I can find that.

    We got a professional to come look at this yesterday. I don't feel so bad at all the time I spent on this because it still took him several hours, so I wasn't crazy.


    Ultimately we discovered that the insert in the Harting connector for RP1 was a little bit broken and when we thought the cable was well plugged in and locked, it was actually being pushed into the hood so the pins weren't actually making contact.


    We couldn't tell anything until we took the connector apart and plugged the insert in by hand and the robot worked all of a sudden. That's how we isolated the issue to a bad connector. In hindsight, the connector could probably plug in both ways because it was just pushing into itself and it really can only go in one way.

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