ABB S4 + IRB2400 startup problem: Diag: Illegal instruction.

  • I have now replaced the motor to an used one from ebay, but unfortunately still the same noise. The pins of the XP1 connector looks nice also the inside. Also the connector is not getting warm, which I would expect with an loose contact.

  • AD
  • Do all the other axes jog without issue?

    Examine all connections between amplifier and motor.


    Line up the chisel marks on the brake again and make sure the commutation number in the parameters matches. Redo commutation, number should be very close to the previous value.


    To eliminate mechanical issues, is there any way you can you run the old motor outside of the robot and still plugged in to axis 1 cable? Coupling the resolver would be the difficult part.

  • Thanks for your reply.


    I also bought now an additional encoder which I will get tomorrow. I will also try your points tomorrow if replacing the encoder does not solve the problem.

  • And then there was grey smoke.



    Today I replaced the encoder and now the noise is far less then it the beginning, although it is still there. Then I placed the robot in the position with the biggest amount of noise and I noticed that by pulling on the encoder cable the amount of noise was changing. From that point of time I got the feeling that the problem is maybe related to the encoder cable.



    But in the mean time I did something else and then there was a strange smell and grey smoke in the S4 cabinet. The smell came from the relays which switch the power to the motor board. After measuring these the resistance was also high for a relays. Then I hoped that this was maybe the problem and found a temporary solution with a relays which can only switch the 3 phases for the motor supply so the other signals are still switched with the old relays. Unfortunately the same amount of noise is still present with this temporary solution. So for this I also have to find a more permanent solution.



    So currently I am searching in the direction of the encoder cable. I am thinking of creating a temporary cable directly to the board. If this solves the problem: how is the cable going through the robot from the base to axis 2? It looks like the motor cables are going through a cable sleeve but these encoder cables are going through the middle joint directly.

  • The burned contactors is K1 or k2 indeed. But I will replace all 4 contactors. I will also check the shielding of the encoder cable.


    Do you know how the cable is going through from axis 1 to the SMB. Is there a drag contact or something else? I see a cable carrier for the motor cables but for the encoder cables it looks like it’s going just through the bearing. But I cannot see everything.

  • A few days ago I have replaced the contactors, this did not solve the problem in the servo however was necesary because of the smoke,


    Today I made a temporary cable from the encoder to the SMB. This is a sub-d 15 (encoder) -> IDC (SMB), which currently does not go through the bearing but is going from the outside to the SMB. This did solve the problem.


    This week I will replace the connector from the original cable as the above is only temporary. Hopefully this will solve the problem because replacing the complete cable will be dificult.

    Edited once, last by rib ().

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