Replacement Duet PWM Issue

tjb1 · 21 Mar 2018, 21:00

I got my replacement Duet which is a v1.02 board (the original was a v1.03). I updated the firmware to match the old one and while using the same config I am not able to use PWM on the print fan at all now on any of the outputs. I have tried changing F in M106 from 500 down to 10 and while I can PWM down to 50% with it at 10, it makes a very loud ticking at that speed and anything under 100%. The fan quits working even at 99%… Was there a change between 1.02 and 1.03 for the PWM?

dc42 · 21 Mar 2018, 21:23

The only change to the fan circuit in 1.03 was to add the fuse in the feed to the VIN side of the fan voltage selector jumper block. The PWM functionality was not changed.

tjb1 · 21 Mar 2018, 22:42

Is it normal to have to take F down to 10 to get PWM to work below 99%?

dc42 · 22 Mar 2018, 09:05

@tjb1:

Is it normal to have to take F down to 10 to get PWM to work below 99%?

With some types of fan, yes. For example, the heatsink cooling fans supplied by E3D. Most of the fans we use were not designed to be used with PWM, so it's amazing that so many of them do work.