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UM2 Electrical wiring questions

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Hello all,

I finally got my UM2 and I am happy, happy, happy, or not!

I am a little disappointed because I notice that Ultimaker still makes some mistakes assembling the equipment . After removing my UM2 from the box I noticed that some screws were not coming completely screwed , and it was not like a 1/4 of turn but rather 5-6 turns. After checking that most of the screws did not come tight , I decided to check and tighten all screws . During this procedure had noticed that some board connectors were disconnected, the ribbon cables were quite twisted and the leds strip was completely detached. The metal plate underneath the heated bed is also scratched . After solving most of these problems I got a question relating to a connector that has the brown and red wires and is not connected to the board . It seems to me that this connector is not to connect and probably will be for dual extrusion porposes, am I right :?:

phew... so much work, it would be preferable if there were a UM2 in kit as in my case before connecting the power already disassembled everything and went back to assemble.

It seems to me that ultimaker have a great product but still having problems on the assembly line and quality control. To me, a robotic engineer, these are minor problems and gave me some joy to solve them, but for sure there will be many unhappy users by observing that the staff of ultimaker not eat spinach and have no strength to tighten screws. :mrgreen:

Thanks in advance for your help


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Yes, there's one extra wire pair that runs from the board to the head and doesn't connect to anything which is, indeed, presumably, for dual extrusion.

One thing to check is the fan on the back of the print head. It should come on immediately upon power-on and stay on all the time. The two side fans should come on together during the print, but not be running before a print starts.


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Thanks illuminarti,

Has always you are in the top of the game, in a superior league. :wink:

In fact i had the rear fan disconnected ?( pink and blue wire), so now that i am sure that the brown and red wire is not to connect i will close the Um2 and fire up and test everything.

Thanks again for your prompt answer


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Note that the pink and blue wire goes to some of the header pins on the back of the board, on the short edge (direct 5V) and not to the nearby and perfectly shaped socket marked 'fan'. That's 24V, and bad things will happen, as I found out.


Ups, You just saved my rear fan, because I made the same mistake as you and just connected to the socket marked as "fan".

Luckily came to the pc to see if there were more responses to the thread because I was 5 seconds of turning on the power. Arrhhh have to disasemble again.

Thanks you save the day and the fan...


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Ahah! I think we probably have the same board (I've never actually taken mine off to see that side of it), but your fan is plugged in to the 'correct' place, while mine (and several other fairly early ones I've heard about) had the fan plugged in to those 'serial' pins... looking at the schematics here:


Those first couple of pins on that serial header are also 5V and GND, so I guess they work just as well. The main thing is not to plug it into the (24V) Fan header on that edge which - on the back side - is just labeled 'Fan'.

Sorry for any panic - and another disassembly - that that might have caused!


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Ahahah! Thanks Ultimaker because you messed up with my printer and I am having a UM2 Kit experience and i am LOVING it.

You are quite right, I was measuring the serial pins and it's also 5V. If the rear fan is supposed to work on immediately upon power-on, so it makes no difference. I will leave mine in "5V Fan" Socket.

Well, this was fun, so back to reassemble...


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