And I just found the problem. I had connected the fan to a JST connector for ease of disconnection. On each side of the connected, I had extended the cable. I mist have got distracted and on one side put heat shrink over the join, but forgotten to apply heat.

Obviously, I didn't notice -- the heat shrink looked like it was in place but had exposed a short.

I'll shrink the heat shrink and then move to a fan output on the Duex!

Trying Safari and the images look like they're working.

And the fan

The MOSFETS do look damaged from the photo.


As for the fan, its a 5015 fan that was included in the printer kit from RatRig so I didn't choose it. It is marked pegnda Technology with no part number (in English anyway) as shown in the photo.


Does anyone have a recommendation for a 5015 fan that won't destroy the MOSFETS?

Fans aren't something I'm used to thinking about. My previous printer (now dismantled with the new one) was running on a RAMPS board which TO220 packaged MOSFETS which presumably can handle much more current than the surface mount ones on the Duet. I'll have to be more careful in the future.

Hi,

I have a Duet2 and Duex5 and am pretty new to the Duet world. I suspect I may have blown two fan outputs on the Duet -- I have no idea how I could have done this and would like some help to determining how this might have happened and how to prevent it from happening again.

I had a part cooling fan connected to fan0 which had been working correctly on my new printer for about a week, and then I noticed it wasn't working. The fan was spinning very slowly and did not change its speed regardless of the fan speed setting. I tested the fan on one of the always on outputs and it worked fine.

I then tried the fan on the duex.fan3 output and fan2, both of which worked. I ended up using the fan2 output and the fan was working correctly for about a day. I noticed that the fan was not spinning partway through a print -- It was working at the start of the print, but had completely stopped by the end. I was using PrusaSlicer's automatic part cooling, so the PWM duty cycle was changing throughout the print. I again checked that the fan worked with an always on output.

I had read on another forum post that the MOSFET can be damaged if the fan outputs are short circuited. I inspected the fan wiring and there does not appear to be any exposed wiring on the cables that could short. I would also think that a short would be apparent when connecting to an always on output. My config.g is attached.

What should I check on my hardware to confirm that it's not damaging the board? Is there a possibility that the outputs are not damaged and I've configured something incorrectly? What tests can I run to determine whether the MOSFETS are truly blown?

I'm not too concerned yet as I still have plenty of outputs on the duex5, but at the rate I'm going, I may destroy these within a week!