Serious fan problem

[veedee 4]

Hi Guys,

I Have a very serious problem here. One of my ultimakers one just stopped working randomly. After I disconnected and reconnected the power cord, the printer works again, BUT, the print-head fan is now constantly spinning at maximum speed, I can't control the speed anymore and it turns on at full speed right after I flip the printer's master switch.

Can someone help me with this problem?

 

[anon4321 16]

Sounds like the darlington pair transistor that controls the fan was shorted. Sometimes they fail closed and the fan runs at full as soon as power is applied.

The question is why? Check for shorts in the cable going from the control board to the hotend especially the connectors.

You will need to unsolder and replace the BD679

Lots of posts on this. See https://www.google.com/search?q=www.google..com&oq=www.google..com&aqs=chrome..69i57j69i65j0l2j5l2.4034j0j4&sourceid=chrome&es_sm=122&ie=UTF-8#q=site:umforum.ultimaker.com++BD679

 

[veedee 4]

Solved, Thanks! I indeed had to replace te broken bd679.