40x28 fan - PWM pin on FAN0 not working
I have gotten to the point where I need to connect the 40x28 4-pin fan to the mainboard (SKR 3).
It's a Delta fan, the PWM wire is blue, and I have connected it to the negative pin on the "FAN0" port.
If the blue wire is not connected, the fan starts as expected at full speed.
If the blue wire is connected, the fan never starts, and any change in PWM on the RatOS interface does nothing.
I have disconnected the Delta blue wire and connected a standard 24V blower fan (known to be working) to the FAN0 connector (red+black) - that fan doesn't turn either.
I measured voltage for the "FAN0" output after manually setting PWM to 100% - it reads 5V instead of expected 24V which is very strange.
At the same time, the heatsink cooling fan on "FAN1" works perfectly.
Tried adding this to override section:
That did nothing to change the situation, still the same behavior.
The picture in the relevant doc (https://os.ratrig.com/docs/guides/4028/) (which I have read several times) only shows an example image for Octopus, not SKR3. My assumption was that I would need to apply the same logic, connecting the fan PWM wire to the negative pin of the standard part cooling fan connector.
Any idea what should I do to change this behavior?
Connecting a 4028 fan | RatOS
4028 server fans are becoming a popular option for part cooling because of their light weight and great pressure and flow rates. In this guide we'll go over how to connect one and use it for part cooling. 4-pin fans usually aren't used in 3d printers, and many boards only provide 2-pin ports, but fear not! There's always a way.
5 Replies
I found the culprit, there are some small components at "FAN0" which are burned, likely from my first unsuccessful attempt of using this board a long time ago.
I will need to configure part cooling fan to use "FAN2" instead (which is used for regulating controller temperature, but I am not using it at all)
in that case 🙂
You'll also have to assign the controller_fan pin to something else, or klipper will complain, so locate an unused pin in the SKR3 pin diagram and do:
that does indeed look like a fried mosfet
Yup. Everything works now, well, the basics, tomorrow I'll do Input Shaper and so on.
This can be closed 🙂
Great đź‘Ť