1 Amp fuse Blowing



  • Hi All,

    I made an error on a new build with polarity crossed and blew the 1 and 7.5 amp fuses. I corrected the issue and I'm now having an issue with the 1 amp fuse blows under heater load. It's a dual extruder (converted Cubex Duo) which I'm I am running 2 x E3D V6 hotends. I find I am able to Auto tune the heaters on the hotends, however when I try to heat a tool the 1 amp fuse blows. Any pointers greatly appreciated.



  • the 1amp fuse is for the fans.

    does the fuse still blow if you disconnect all the fans?



  • Hi Veti,

    Thanks for your input. Unfortunately yes the 1 Amp fuse blows even if the fans are disconnected. I've also connected the fans to the always on an they seem to function correctly.



  • and all fan outputs work fine before heating?



  • @Veti

    I've not checked the fan outputs. I have checked the fans operate on the always on outputs and they were fine. The fans also work when I auto tune the Hotends.

    The fuse blows when I request heat to be applied to the hotend whether from manual input or from running the preheat macro.



  • Hi Again Veti,

    I've not checked the fan outputs. I have checked the fans operate on the always on outputs and they were fine. The fans also work when I auto tune the Hotends.

    The fuse blows when I request heat to be applied to the hotend whether from manual input or from running the preheat macro.



  • my thought was along the lines of the pwm fan mosfet being blown. and when for example the part cooling fan turns on, it creates a short circuit.



  • Thanks for the insight really appreciated, I'll look at testing the mosfet.


  • administrators

    Are you certain that you didn't get the fuses swapped? Turning a heater on shouldn't blow the fan fuse.



  • @dc42 Yes, absolutely correct fuses swapped, now running fine. Thanks for your insight, very much appreciated.


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