PWM 24v fans?



    • I have a Duet 2 WiFi going into a 24v Artillery Sidewinder. I’ve been working all day trying to get the fans to work and I’ve read about all I can.

    I have my layer fan plugged into Fan0 and when controlling it through the DWC at 100% the most I get is 8v at the fan.

    As for the Hestbreak fan, it’s connected to Fan1 and it doesn’t do anything at all. Both fans work at full blast on the “always on pins”.. but for the PWM only fan0 works and it’s just barely sending 8v...

    I have 24v into the board and all the fuses are good.

    Am I doing something wrong?



  • Please post your config.g.

    Ian



  • @TheLightSpeed said in PWM 24v fans?:

    just barely sending 8v...

    if you have the fan jumper on 24v the positive is directly connected to vin.
    the duet switches on the negative pin.

    so it should always be 24v. did you check for a short?



  • @Veti I don’t see anywhere that explains the jumpers? I didn’t mess with them at all.



  • see
    https://duet3d.dozuki.com/Wiki/Duet_Wiring_Diagrams

    its called v fan jumper select



  • Okay I see it... so I don’t have anything on those three pin jumpers? To use 24v fans should I?



  • Put the jumper between vfan and vin.



  • Thank you! I just ordered a new board because I’m pretty certain I fried this one. Expensive lessons. I would have thought the PWM fans would be default 24v? I think o fried it by having the end stops pinned wrong. I didn’t think to check them and just put them on like the MKS board had them. So I just pinned them correctly. Is there anything else like that? That will fry the board?



  • @TheLightSpeed said in PWM 24v fans?:

    I think o fried it by having the end stops pinned wrong. I didn’t think to check them and just put them on like the MKS board had them. So I just pinned them correctly. Is there anything else like that? That will fry the board?

    This shouldn't fry the board. See https://duet3d.dozuki.com/Wiki/How_to_destroy_your_Duet_2#Section_Methods_that_probably_won_t_destroy_your_Duet

    Short the endstop supply voltage pin to ground. This is a particular favourite of Arduino/RAMPS users, because on those boards it is very easily achieved by plugging in the 3-pin endstop connector the wrong way round. Doing so when using NC endstop switches will short 5V to ground, which is almost guaranteed to fry the 5V regulator on the Arduino. But we thought of that. First, we use polarised Molex-style connectors - although you can subvert that quite easily by plugging un-polarised Dupont-style receptacles into them (you'll need to throw away the polarised mating connectors that we supply with Duets). Second, we changed the pinout, so that the common case of reversing the connector has no effect when a simple microswitch (the most common type of endstop switch) is used. You can get around that by pretending that the only endstop connectors you have are the ones left over from when you were using RAMPS, and you 'forgot' to re-pin them. Buit third, we used a voltage regulator chip that tolerates short-circuits. We even added a circuit to ensure that the heaters are turned off if you short the +3.3v supply (the supply provided on the endstop connectors) to ground.

    Ian


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