Print cooling fan will not turn off


Have been printing a while with my Wilson II from Marty’s kit. no modifications done to it other than boosting the voltage on the power supply to get more heat, and adding some insulation to the bed. Right now I try to use octoprint to turn off the print fan with either M107 S0 or M106 S0 commands and neither will turn it off. clicking the button issues the command but then doesnt turn it off either.

I’m really stumped here. I soldered an RC connector to the fan so that I can unplug it when i’m printing ABS but it’s not the ideal solution. It did use to turn on and off before using cura’s fan settings, and octoprint, but it’s stopped.

Would anyone have any other places to check the board, or any other tricks?


Where have you got the fan connected to?

If its a PICA it is FET4

If you have changed the firmware you may have to check the Pin definitions in the firmware


I have the stock pica board, and the fan is connected to the fet4 connector as described. Have not updated the firmware (too chicken at the moment heh).

my fet4 connector looks a bit different than the one pictured. mine is a white connector rather than the standard female jumper connector. i’ve tried disconnecting it and reconnecting it, doesnt solve the problem. wondering if I should update the firmware to give it a shot or not, but hard to imagine that it’s a firmware issue. I’m almost wondering if the transistor that fan is connected to has latched into the on position in some way. no way to tell if that’s the case though


This the First PICA I think I just pulled the pic from Marty’s post on the release. You probably have the latest board.

If you can turn the fan on and off from the LCD by going into Temperature and changing the number and it works… then it’s an Octoprint thing.

I haven’t played with Octoprint but is this the issue.