Jump to content

Recommended Posts

Posted · Mark 2 expansion board with reversed diodes!

Recently I was wondering why of my freshly built Mark 2 printer the hotend fan and the model fan of the 2nd hotend won't work.

Today I have taken the time to analyse it. Started by putting the printer to its side, opening the Mark 2 expansion board box and measuring the outputs of the board. Finding that there was no voltage on the fans. I noticed that the expansion board was rather hot on one side. My thermal imaging camera (flair one) said it was actually 80 degrees C hot. I saw it was the 1k resistor near the 6 pole header coming from the control panel board. Weird!

So I unplugged the expansion board and took it to the desk to check what's wrong.

Resistors were ok. One of the transistors had a short, the other at least no proper diode voltages. So it seemed the transistors were dead. But why?

Umm. Shouldn't the diodes be the other way around if they are freewheeling diodes. Checked the schematic. Checked the diodes.

 

Yes, they were mounted the wrong way!!

I bought the board completed, so the manufacturer mounted the diodes the wrong way and that seems to have killed the transistors....

 

So I reverted the diodes, mounted new BC817 transistors, reassembled the printer ... and ... it works, the fans are alive!


@DidierKlein, who is assembling your boards? :-)

  • 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 5.9 stable released!
        Here comes Cura 5.9 and in this stable release we have lots of material and printer profiles for UltiMaker printers, including the newly released Sketch Sprint. Additionally, scarf seams have been introduced alongside even more print settings and improvements.  Check out the rest of this article to find out the details on all of that and more
          • Like
        • 5 replies
      • Introducing the UltiMaker Factor 4
        We are happy to announce the next evolution in the UltiMaker 3D printer lineup: the UltiMaker Factor 4 industrial-grade 3D printer, designed to take manufacturing to new levels of efficiency and reliability. Factor 4 is an end-to-end 3D printing solution for light industrial applications
          • Heart
          • Thanks
          • Like
        • 4 replies
    ×
    ×
    • Create New...