Those 2 fan output connectors are controlled by a transistor (actually probably a mosfet) that can die pretty easily. Especially if you put a heavier than expected load on them. They can die in many different ways. The most common I think is an open (always off) and the second most common is a short (fan always on) but I wouldn't be surprised at all if there are other failure modes for that poor little "transistor".
Even without heavier than expected loads those transistors occasionally fail. Switching the fans on and off 20X per second (normal operation when fans are anywhere from 1% to 99%) can cause them to get pretty hot.
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jaysenodell 18
Check the klipper references (https://www.klipper3d.org/Config_Reference.html) on how to set that pin properly. Effectively that pin is operating with "high" as the default and inverted (ex val = HIGH - val is how that is managed in mcu land). Sometimes this is done with a hardware default (v+ -- fet -- pin with the fet controlled by the pwm pin) in which case you will need to tell klipper to invert the signal. Something like
map(val, high, low, low, high); // stdio map function
Given klipper's open arch you should be able to write a couple lines of python to achieve this with ease.
I"m neither a ultimaker or klipper person, but I do recognize the patterns here. Good luck.
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garthondo 0
Thanks for the suggestion. I was able to invert the pin per your suggestion via a "!" as a prefix when defining the pin name after looking at the config reference. However, the pin now has a voltage of ~15.5v when at 0% and ~16.1v when at 100% when it is supposed to be ~0v at 0% and 24v at 100%. I believe the pin worked fine before I messed with the fan wiring, so I still suspect that it was possible that I damaged it, but not sure. I also looked at some klipper config files for a similar machine (um2) that uses the exact same board and the pin is not inverted. Maybe that extra info about the voltage might be useful to some?
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