low voltage from duex2 fan/led headers

  • My 12v fans dont run quickly when connected to the duex2 when set to 12v. When I connect them directly to a 12v source, I get much higher speeds. The LEDs dont sem to care. Im getting a hair above 10v and that's good enough for LEDs.

  • Moderator

    @Mentaluproar Do you have a short, thick, ground cable going between the Duex and Duet? Without it, signalling between them may not be optimal. See https://duet3d.dozuki.com/Wiki/Duex2_and_Duex5_Features#Section_Wiring

    Otherwise, post a picture of your boards and wiring, your config.g and response to M115.


  • The duet and Duex2 are right next to the power supply with decently think wires directly to it, but I recognize the ground should be chained between boards and will correct that. That being said, when it was just the duet board, it also drove fans slower than direct connections. I’ll post more info when I get home, but the wiring isnt likely to be easy to get from just the pictures.

  • Okay, so I corrected the ground wiring to the duex. The problem persists. Out of curiosity, I put a multimeter between the fan voltage select pins on the duex. 5V pins read 1.1v. 12v pins read 6.85. Vin read 18. It's a 24v system. I'm not sure if this information is actually useful, but it was interesting.

  • Also under the heading of 'interesting' is that I have the same issue. The only thing different for me is that when I tried to measure the header voltage I managed to short the lines out with the probes and the magic smoke left the driver 😞
    For obvious reason I have abandoned (until the FET is replaced) to measure fan voltage.

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