Solved Toolhead PCB problem

[orge]

On a 2.4 i am trying to mount a toolhead pcb.
Heater and probe is working
The main problem is the fans are not running.
When connecting the fan directly to the octopus, it runs, but not when mounted on the toolhead pcb.

I have only one wire from octopus to the toolhead pcb for each fan.
It is a LDO PCB kit

Problem is for both fans

 

[WhiteWulfe]

Are you using the breakout PCB that's mounted in the electronics bay, or are you running wires from the Octopus to the toolhead board? Can you provide a diagram of how you have things wired?
Which LDO PCB are you using, Afterburner or Stealthburner?
Have you verified the polarity of your fans matches that of the headers on the toolhead PCB?

 

[DocFoFo]

what was the resolution?

 

[orge]

Actually I don't recall the solution, but I think it is something with a common supply og 24V for the fans

 

[Sandman50]

The fan wires from the toolhead connect to the negative pin, not the positive pin on the main board. The fans pull voltage from a common high voltage rail.

Perhaps backwards from a non EE context, but the mosfets close the circuit to ground, vs. close the circuit to the high voltage rail.