Fuse blows in Process I/O board CA after start-up

  • Hi, customer has R-30iB cabinet with M-900iA/600 robot.


    Today the 2.0A fuse in Process I/O board CA (A16B-2201-0470/10F) blew when robot was going to change tool and PRIO-093 alarm was shown in screen. When we replaced the fuse and switched power on the fuse was blown again right away. We thought that the reason was in EE cable since the fuse didn`t blow at first when we disconnected that, however at some point the fuse was blown also when EE was disconnected. The customer told us that same fuse has blown before sometimes and when they have changed that then it has been working fine again.


    One thing that comes to my mind is that there might be loose wiring somewhere that we couldn`t recognize but is there anything else that would cause this kind of behavior?


    We have A16B-2201-0470/07C I/O board in stock. Can we try to change that?

    Edited 2 times, last by ophakala ().

  • Hi

    Assuming wiring is done correctly and there are not lose wires that can produce short I want to tell you :


    Fuse for the EE is very delicate.

    I've blown many during many years. It doesn't like sudden voltage changes. Just because I disconnected and connected again was enough to blow the fuse.

    I don't remember having a fuse blown with tool changing

    I got to the point that I will turn the power off, work on the EE, connect sensor or other devices and with the EE connected I will turn the power on on the robot.


    Do not try to replace the 2A fuse for something bigger. Bad practice

    Retired but still helping

  • Hi, I was not planning to change fuse to bigger one. Just wasn`t sure if this other I/O board is suitable for that system but Fanuc already told me that it`s okay.


    We tried turning power on when EE was connected and when it wasn`t, the result was same everytime. Do you know if there is something else affecting that fuse besides EE? I couldn`t find a circuit diagram of that.

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