Heater test tripping protection circuit



  • So I'm a little lost on this one... I'm just starting to test the printer and everything was going well, motors work, thermistors work, etc but when I try and set a temp on the bed heater everything turns off. Board shuts down, PSU turns off... everything. I can turn it off and on again and things are fine but I have no idea why it's doing it. I don't believe I have anything wired wrong, it's pretty simple. Perhaps I have something configured wrong in the firmware? I'm really not sure.

    any ideas?



  • Can you give some more details? Is the heater AC? DC? How is it wired? What PSU? What duet board? Firmware version?

    Definitely double check your wiring.


  • administrators

    What bed heater is it, and what PSU are you using?



  • I think my issue is the heater is 12v and I have everything setup as 24v but just incase, it's a duet maestro, 24v psu (don't recall the name but like a meanwell) firmware is whatever the board came with, not sure at the moment... 2.0.? I think that's right. Everything is DC as far as I know. It's wired to the bed heater terminal on the duet, ground to ground and positive to positive.


  • administrators

    @screwyluie said in Heater test tripping protection circuit:

    I think my issue is the heater is 12v and I have everything setup as 24v but just incase, it's a duet maestro, 24v psu (don't recall the name but like a meanwell) firmware is whatever the board came with, not sure at the moment... 2.0.? I think that's right. Everything is DC as far as I know. It's wired to the bed heater terminal on the duet, ground to ground and positive to positive.

    That could certainly explain it. If your bed heater is a typical PCB bed heater about 200mm square, then at 12V is will take around 10A. At 24V it would draw 20A, and unless your 24V PSU is rated above 480W, that's more than the PSU can handle. So the PSU overload protection is probably cutting in.

    Some PCB bed heaters are dual voltage, and can be wired for either 12V or 24V. These types have 3 connection terminals. If yours isn't like that, you will need to get a 24V-compatible bed heater.



  • thanks for the reply... that's kinda what I figured. unfortunately my 24v bed is in chinese shipping limbo... I just had this one laying around hoping to do some testing but I guess that's not gonna work and I'll have to wait.



  • You could test printing PLA which can be done without a heated bed, and you might be able to run your heat bed off a 24/12v converter if you have one (which needs to be rated for your load) to bridge the time until your 24v heat bed arrives.


Log in to reply