Fans connected to ramps board?

So I printed and slightly modified a case (, for the electronics.

I tried searching, but I am not sure where the best location to plug in these fans would be. I purchased all the electronics and hardware directly from vicious.

If someone could help guide me in the right direction that would be great.

Thank you,

If they’re 12v just wire them to your dc in on the green connector. I don’t think the pins on the ramps board will support both at once. They’re the single pair between the x axis driver and the dc in plug.

Hi Barry,

Thanks for the response. They are 12v, Is there anything special I need to do, or watch out for, using the green connector?

If you are not going to use the MPCNC as a 3D printer, you can wire it to the D9 plug (hot end fan) and control the fan using repetier and/or in your gcode.

To use the D9 plug you have to put 12v to both input jacks on the green molex connector. You can use jumpers from one side to the other like Ryan has pictured here

M106 S255 ; turns fan on at full speed
M107 ; turns fan off


Thank you for the info, and the schematics. I am not going to be using it as a printer, as I already have a lulzbot taz 6, so this looks like it “should be” pretty straight forward from here on out!

Thank you so much.

I wouldn’t install them on D9, because you want them on whenever the drivers are on, not just when you are cutting. Either the green input, which is just wiring them into your power supply, or there is 12V on the extra stepper bays, too. But the green is what I see most often.

There’s nothing tricky about the green, just make sure all the wires are in there securely. If the power falls out during a cut, you will not have a good day. And red to red black to black.

Ignore the yellow wire, it’s just the tachometer signal wire so computers know if the fan is spinning.

Tom, Jeffeb3, and Barry. Thank you all so much for your information. I know I may ask some obvious questions, and I tried searching but I am just getting into electronics and this whole new world so a lot is not that obvious for me, “yet” :).

So again, I just wanted to say thanks for taking the time to help me.