Led on Fan out6

Heartleander81

Hi I wanted to connect a stepdown module (from 24V to 12V) to out6 and a 12V Led stripe.
I already had the LED on out9 when it worked.

M950 F6 C"out6" Q500                               ; create Light on pin out6 and set its frequency![undefined](undefined)
M106 P6 C"Licht" S0 H-1

In the firmware I changed it from out9 to out6, connected the board to set the stepdown, turned out6 (fan control) off and there was still power on the module.
Funny.
So board off, plug down board because I wanted to measure ... fizzel mosfet defective.
What was my mistake?
Was it the stepdown module?

dc42

Never connect a heater or fan output to the input of a step down converter. The high surge current drawn by the input capacitors of the converter will destroy the mosfet. The correct way to use a converter is to connect it to VIN, and connect the LED or fan or other load between the positive output of the converter and the OUT- terminal of the output. There is some discussion of this at https://duet3d.dozuki.com/Wiki/Connecting_and_configuring_fans#Section_Using_12V_fans_when_VIN_is_24V and the following section.

Heartleander81

@dc42 oh. But He look not good. ??

Oh is a Duet3 6HC Board. I forgot to write about it.

Heartleander81

Ok will use a switch version and not go overboard for the LED. Which part is in the picture? it sits directly above the Out6 and looks defective. So far everything is going well.

But I have understand how I can use a 12v fan in a 24v System.

dc42

@heartleander81 that looks like the out0, out1, out2 or out3 mosfet to me. I don't have a 6HC board in front of me to check which.

Heartleander81

@dc42 ok. Them is out3 but on this pin I dount have anytime a heater ore something connected.

Ok then test I the out9 with a fan. I hope it is ok...

Thanks DC42