Jump to content
Ultimaker Community of 3D Printing Experts

The 25mm print head fan is making me crazy!

Recommended Posts

Hi guys!

I just got the UM2 from a friend to use.

I found out that the infamous print head fan is not working.

I checked the wirings....even took off the whole connector and joined the wires together.

I found that before doing that, the fan had like 5% life in it. It turned like a a 1/4 turn from time to time and then stopped totally after i had played with the wires for a while.

I took the mainboard cover off too and checked, that the wires are all attached.


Is it black and red wire coming from the print head supposed to connect to the edge (facing the screen) of the board?

Was it 19-24V or so?

The Yellow-Green wire goes to the pwm connector next to the led connector.

What's the 5V fan connector in the middle of the board for?

I would think that, the Black-Red wire from the head would go there, but am I somehow mistaken here?

Share this post

Link to post
Share on other sites

There are 3 fans on the printhead - not sure which fan you mean. The 2 side fans are wired in series - joined by a jumper wire (usually green). The side 2 fans take 24V in series so they get 12V each. To turn them to 100% is tricky:

select PRINT, then choose anything in the menu to print, then immediatly choose TUNE and scroll down to fans and set to 100%. The printer won't start printing as long as you stay in the TUNE menu. As soon as you leave that menu it will start printing if it is warmed up so you might want to just cut power instead.

The 3rd fan - the rear fan - on some models it comes on when you power on - even before the lights. On newer models (2015) it only comes on if the test head is above 40C. That one is a 5v fan. Typically it runs from a connector near the middle of the board.d

Share this post

Link to post
Share on other sites

You can take a look at the assembly manual (page 65) - but as gr5 said: be aware that the recent changes (from 2015) are probably not included yet.


The side 2 fans take 24V in series so they get 12V each.  To turn them to 100% is tricky:


@gr5: you really should accept that there is a menu option for this since firmware V14.10

"Maintenance -> Advanced -> Set fan speed"


  • Like 1

Share this post

Link to post
Share on other sites

The side fans are working great!

It's the smallest fan in the center that cools the nozzle that buggers me.

I connected the connector to the center of the mainboard, that was fitted to the side of the board to the pin that says "19-24v". I tried to get a voltage reading from the connector on the center, and the whole UM2 shuts down for as long as i keep the wires connected to the multimeter.

Then i connected the wire back to the side of the board, where it was in the first place and it reads around 25 volts.

I just wonder, how in the world could the small 25mm fan ever take that kind of voltage.

Share this post

Link to post
Share on other sites

You may have blown up the fan. That 3rd fan is a 5v fan. I have several and I was planning on selling a quieter version than standard in my store. I've been testing it and it seems to work fine. History: my UM2 was one of the early printers - probably around the 300th printer. It had a very very quiet fan - I even did a video to show people how quiet. Later when I got my UM2go I was annoyed at how loud the fan is. It turns out it is a different part number. Anyway I would like to sell these in my store - if you are in USA then I can send you one for say $5 plus $3 shipping since you will be a beta tester. Complete with connector crimped on. If interested contact me at thegr5store _at_ gmail.com

Oh and the 5v fans I have I accidentally put about 10V into it and it died within about 0.5 seconds. I have about 5 of them.

but be aware that this is not the standard fan - this is the model of fan that came with the early UM2's before they switched. It is about 1/10 as much wind but it seems to be plenty of cooling power as I've printed 30 hour prints with tens of thousands of retractions just fine on my UM2 (still testing on the um2go).

Share this post

Link to post
Share on other sites

Thanks gr5!

I ordered a fan from UK that is made for RC cars. I will test the output from the board with that and then get back to you about it.

I live in Finland, so shipping will be more tho.

I've done a 2 hour print without the fan now, and haven't had a problem (yet)

Still playing around with the temps and other settings.

I'm so new with this.

It seems like the printer was assembled wrong from the factory, as the guy i got this from, has only used it slightly and i know for sure that he hasn't opened the printer and swapped the connector for the fan to the 19-24v pin, where it was connected when i opened the thing.

One weird thing is the front right corner of the machine, that seems to be about 5mm off the table top.

I measured the side panels and the bastard is about that 5mm shorter than the other side panel.

I wonder why the other guy just accepted that when he got the printer in the first place

Share this post

Link to post
Share on other sites

One weird thing is the front right corner of the machine,  that seems to be about 5mm off the table top.


These printers turn from rectangular box like shape into parallelogram shape during shipping.  This often affects the print quality.  if one corner is higher then the 4 bars over head are probably not in the same plane but are in a saddle shape.  When printing large parts and printing the brim or skirt - some times you can't get it quite level because 3 points leveling is not enough.  This can be caused by the rods not being parallel/perpendicular.  this can be fixed by loosening the panels and pushing it back into shape.  Alternatively your rods may all be in the same plane but they may look like a parallelogram from overhead.  This causes square prints to be parallelogram shaped from overhead view.  Again - loosen all the panel screws and push by squeezing on the long diagonal until it is back to square.

Edited by Guest

Share this post

Link to post
Share on other sites

Ok thanks!

I'll try that tomorrow, when i have the time.

All the 20x20 hollow cubes look like they are not straight. The layering is fine etc, but something about them looks wrong.

Also, when looking from the front, the right hand side front corner of the build plate is seemingly higher than the left side after levelling.

So high, that the adjusting screw almost pops out any minute.

I'm still waiting for the new hot end fan to arrive, so i can go on and test that the 5V outlet on the center of the board gives power.

If it's dead, i will need to find a way to get power for the fan somewhere else.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Our picks

    • Ultimaker Cura | a new interface
      We're not only trying to always make Ultimaker Cura better with the usual new features and improvements we build, but we're also trying to make it more pleasant to operate. The interface was the focus for the upcoming release, from which we would already like to present you the first glance. 
        • Like
      • 9 replies
    • "Back To The Future" using Generative Design & Investment Casting
      Designing for light-weight parts is becoming more important, and I’m a firm believer in the need to produce lighter weight, less over-engineered parts for the future. This is for sustainability reasons because we need to be using less raw materials and, in things like transportation, it impacts the energy usage of the product during it’s service life.
        • Like
      • 12 replies

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!