Duet 3 Mini5+ Heat Pad



  • Hello guys,

    I would like to confirm a doubt I have about connecting the heating pad in the duet3 mini5+. Will the bed heat up with the connection below? Or is a "jumper" between Vin (Power In) and V-Out0 (Out0) necessary?

    test_heat.png



  • Thats fine.
    You will want to think about adding a thermal fuse to the bed etc.

    You don;t have to use Out0 though, you could just as easily use one of the fan outputs and save Out0 for something like LED lights etc



  • Yep, can confirm - that will work and exactly as @jay_s_uk wrote - definitely get a thermal fuse, especially if you want to use a Fotek (in case it's a fake and there's loads of those around).



  • I would not use a fan output for a heated bed SSR. If the board comes up weird/with a broken config, the default fan outputs will spin up at 100% which would put the SSR at full power, quickly heating up an AC bed. Here is a photo of someone who had that happen (with klipper though) and the bed got full power for only three to four minutes:

    image of a print beds magnetic surface bubbling from excesisve heating

    There was no permanent damage in this case, but still a scary moment for the person it happened to. A thermal cutoff fuse should be in place either way.



  • @oliof that would also happen with a hotend output as well wouldn't it?
    They are all just mosfets after all.



  • No, the hotend/heater outputs don't go to 100% on startup as a safety feature to avoid cooling interruption to the hotend.



  • @oliof ah yes, forgot about that. I don't think all fans do it though do they. I have a feeling it might just be F1. Don't know if its the same on the mini 5+ and duet 3 though as the outputs are that flexible



  • Since at least on the 1LC toolboard the fans go full blast until CAN is synchronized and the config is uploaded, I expect the Duet3 family to have a failsafe default setup to run until they see a valid config.g ... but I might just test tonight with the Duet 3 mini that's on the workbench anyways.


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