Fan Oscillation RPM
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I have a RatRig CoreXY printer using Duet 3 Mini 5+, and my 4028 fan slooowly oscillates during normal use. If i am printing it will go frmo 2500 RPM to 3500 RPM over a 10 second period, then back and forth over and over. This only happens when the hotend is on and printing. even if i pause a print, the fan behavior continues to oscillate.
The fan has its own 12 volt PSU, but its negative goes to a spare heater connection negative on the main board. and its tach and control pin connect to the 1LC toolboard. this oscillation behavior happened even when i used the main board fully and did not have a toolboard.
The fan is AVC 4028 12V 1A DBTB0428B2G 15,000 RPM from Amazon, its not the SanAce from RatRig. The SanAce seems like a much higher quality fan.
i've been running a few weeks, i dont notice any burning or wiring issues. the wire gauge of the fan seems small i'd guess 29-32 gauge...just guessing. the wire OD measures 0.8mm but i dont know the ID.
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@rogerpodacter Which "spare heater connector negative" are you using? On Duet and (pretty much all) printer control boards fan/heater outputs switch the negative line line (to provide pwm control), so there is a good chance that this connection is not connected directly to the negative supply. I would move that connection so that it is directly connected to the power supply and see if you still have the problem.
