Thanks Martin,

But it worked before, the small extruderfan was running good. I just changed the FW for the z-steps. Could the x44 output have been killed?

Its a 24v fan.

/C

Hm, maybe there are "special" fans which work directly on a PWM output without low pass filter? I don't know.

I can only speculate. Maybe some "random" thoughts can help you:

1. Are you sure it worked at different speeds? I would expect a fan (even an "ordinary" one which needs a low pass filter) to work when the PWM is set close to full speed.

2. Hence try out if the fan works if you set it to 100%. In that case there should be no PWM, the output should be permanently on.

3. Maybe you accidentally changed the PWM frequency as well. Maybe the fan works only if the frequency is correct. Can you try the various options? This should be configurable through the menu, at least in case of the community firmware.

4. Of course it is possible to destroy such output. The direct MOSFET-driven output should be a lot more robust than the X24 12V fan output, because that one has the weak Z diode which is known to break (mine is already broken). But those outputs can also provide a lot more current, which can potentially be dangerous. It is probably advisable to have some fuse in the loop to protect the board from damage if a short circuit happens. I can't tell how fast the output would die in case of a short circuit, or if maybe the mainboard would be kind of "self protected", because a short circuit will cut off the power to the microcontroller as well (power supply will detect over current and shut off). That depends mainly on the strength of the PCB traces, connectors and solder joints. The MOSFETS are pretty strong, they are rated up to 100 Amps. That is referring to proper cooling which is not the case, but heatup takes a while, so you would have to have a shortcut of many seconds before they might get damaged.

5. You have 3 more outputs which are in principle identical: X19, X42 and X45. If one of them is free, you might try it as a replacement. That will need a firmware change, but you already had to do the firmware change to use X44 instead of X24, right?

Martin,

Thank for info. I swapped x44 to x42 and changed in FW. All is now working. PWM to 255. No clipping sound either. Must have damage the x44.

Again, thanks all!

Then I strongly recommend adding a fuse