6HC and 3HC always on fan

[Miasmictruth]

I have been trying to find out how much current is supplied from these always on fan ports on the 3HC and 6HC, but the documentation just says always on fan with no amp rating.

I have a CPAP blower with a driver that needs 24V and 5V pwm. I was going to use a heater output so I could turn the 24V on and off but strange things happen as the ground on the 24 and 5 are connected on the driver, and I didn't really want to power it directly off the power supply.

Thanks.

[Phaedrux]

If the always on fan ports are getting power from the 12v regulator than they are limited to 1a.

https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Hardware_Overview#Section_Heating_Fans

[Miasmictruth]

@Phaedrux No they are off of whatever vin is according to the wiring diagram. I also verified this with my multimeter they are 24v

[Miasmictruth]

@Phaedrux The only mention of the pins on that page is this, which has no mention of current.

2-pin KK header labelled GND and V+: This is for powering an always-on fan or similar. Caution! On v0.5 boards the GND and V_FUSED legends on the underside of the board are the wrong way round! The ones on the top are correct. Note: on the v0.5 board this connector is rotated 180 degrees compared to the intended orientation on later version boards.

[dc42]

I recommend maximum 2A load on the Molex KK connectors, although in theory they should be OK at 3A.

[Miasmictruth]

@dc42 Thanks!