Fan Issue

  • Hello all!

    I am experiencing a rather perplexing issue. There are 3 fans wired to the FAN0, FAN1, and FAN2 ports on the Duet Ethernet. All 3 fan ports will work correctly with two fans, however a 3rd fan will not turn regardless of which port I try. The fan will spin up for a brief moment and then stop spinning. I am running fairly large fans:

    I believe the issue is related to the fan, however I would like to be sure that I have missed anything before I order another fan.



  • there is a max amp of 2A for the fans.

    3 of those would exceed it.

  • That may explain part of the issue! However the fan still won't operate if it is the only fan plunged into any of the 3 ports. Would that lead you to believe the fan is bad?

  • Moderator

    You may need to experiment with different PWM frequency (F parameter) values in the M106 command. Those are some pretty hefty fans. I would imagine they require full power to spin up from a dead stop, so maybe add a few seconds of blip time with the B parameter as well.

    Does it work if it's connected to the always on fan port? How bout connected directly to VIN?

    What version of Duet PCB do you have? Perhaps you've blown the fan fuse or mosfet.

  • The fan will not work if it's connected to any of the other fan ports including the always on port. I haven't tried directly powering the fan by VIN, the duet is in an enclosure and it's a pain to rearrange things.

    I believe the board is revision 1.04. Again, the board is in an enclosure and it's a pain to see what the silk screen on the board reads.

    The printer is using larger fans since we're running a pellet extruder and we need to move lots of air quickly to cool parts. 5mm wall width at 1mm high means LOTS of heat retained in the print.

  • Moderator

    If it's a 1.04 board there is a blade fuse for the fan ports. Check if it's popped after you've verified the fan is actually working by connecting it to VIN.

    Once you've got that rectified you can test to see if the fan can work at all by modifying the frequency and blip.

    That still doesn't solve the problem of being above the Amp draw for the fan ports. Lower draw fans or an external mosfet maybe?

  • @phaedrux Given the hassle with wiring something new into the Duet, I'll go with lower draw fans. They might set me back a few bucks but it's not a big deal.

    Also the blade fuse isn't bad, so I think I'm in the clear!

    Thanks for the help! Also, I love your avatar. Hyper Light Drifter is one of my favorite games.

  • Moderator

    @kzamani said in Fan Issue:

    I love your avatar. Hyper Light Drifter is one of my favorite games.

    Ha. Thanks. Mine too, if only I didn't suck at it so much.

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