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Cooling fan connection issue

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I found a connection issue that affect the cooling fans power on a UM2 I got last week.

The issue seems to be located at the head of the printer where the main wire line goes in. If I turn the wire around the Bowden the connection is restored. The wires that connect directly to the cooling fans are ok and the rear fan is always working.

IMG 2866 Segment 0 x264


I'm pretty sure this is the cause of so many issues I'm having with warping and overhangs. Has you can see the new print in progress is much cleaner when I make sure the fans work.

IMG 2867 warping

I know the fans are getting on after 0.5mm height but are they supposed to always stay on at 100% during the print (based on cura settings)? What is the normal behavior of the cooling fan?

How should I go and takle use in order to fix the connection issue?




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Depending on the slicing settings in Cura, the fans have a "fan speed min" and "fan speed max" (advanced settings menu "Expert" -> "Open Expert Settings"). If you set 0.5mm then the two side fans will gradually start spinning until they reach 100% speed at 0.5mm. However the settings for min and max are a bit more involved - check the tooltip help.

But the fans should stay on after they have reached full speed. The slow start you see in the video is normal. Sometimes the impulse is not strong enough to overcome the bearing resistance from the fans. I had it a few times where I had to manually nudge the fans to start spinning.

Which problems do you experience with the cable connection? Do the fans stop spinning mid print?


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Ok, then the connection is faulty. I'd suggest you should try to pinpoint the location where the connection is broken. If it is a broken wire, this can be easily repaired (although re-soldering might be tricky depending on the location on the wire). Did you check the white molex(?) connectors? Are they seated properly?


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It really seems located at the connection of the main wire line and the print head so if the molex connector is at that place it could be the cause.

I'll look into it more tonight. I noticed the faulty connection this morning just before leaving for work.


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To test fans without printing anything, go to the PRINT menu, select that and select any print. Then quickly select TUNE menu and it will not print until you exit print menu (you can hit power switch when done). Then go to the fan control in TUNE menu and set to 100%. They should come on full speed.

When done you can either exit PRINT menu and quickly abort print (but it will probably print a little) or you can just kill the power.


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