UMO - Nozzle temp stuck on 130 degrees and flickering controller screen

[MVerel 0]

Hi Guys,

I work at a school where they have had an UMO for a couple of years now (about 5). It was built by a couple of our students, but they never got it to work very well. Over the years students sometimes managed to print stuff, but the printer has never been reliable.

Since I work here (about 1,5 years), I have tried to get the printer to work properly. I have been busy unclogging, recalibrating, rebuilding some of the parts (like the feeder, which was never assembled properly) etc. and finally got the printer to work somewhat reliable.

However, after a couple of prints, the hot end kept leaking and clogging, and the temperature readout would get stuck on 130 degrees. Because the temperature sensor looked damaged I replaced it and put a new hot end in the printer, hoping it would solve both issues. Since then the leakage has reduced to almost nothing and the PLA we use has flowed better than ever. For about three prints that is.

Since then the ultimaker controller constantly says the nozzle temp is 130 degrees. The hot end gets too hot to touch. When I tell the printer to preheat, the bed is heated and registered properly, but the temp. of the nozzle does not increase. After a few seconds the screen of the controller strarts flickering and eventually says "Heating Failed".

Too see what the problem could be I checked the following things:

 

• The firmware is upgraded to the latest marlin version
  
• the connectors on the controller, motherboard on the bottom and on the temperature coupler are secured
  
• when I remove the connector on the temp. coupler the temp on the controller changes to 180 degrees.
  

 

Does anyone have an idea what the problem could be? Thanks for your time in advance.

-Mathijs