Hi,

I'm trying to create a simple setup with an extruder, a hotend and a fan (all components of the Prusa MK3S) using RAMPS 1.4 and the Marlin software. Unfortunately, the attempt to set a temperature for the hotend is always cancelled at around 40 degrees. (I also use the thermistor on the Prusa hotend here). Does anyone have any idea how I can get the hotend to work?

Many thanks for your help

Prusa Mk3S has 24v volt components including the hotend heater cartridge the ramps is 12v. this will not work together.

The Cooling Fan 5015 50x50x15mm from the Prusa mk3s is 5v so you cannot plug that into any of the ramps mosfets either, they all run at 12v.

There are hacks you can do to change a ramps to 24v [reprap.org]

Or get yourself a 40watt 12v heater cartridge

Edited 2 time(s). Last edit at 07/12/2024 11:28AM by Dust.

Thanks for the quick reply!

I have tried to solve this problem with dc dc voltage converters behind the outputs for hotend and fan. So a power supply with 12V 8A. A converter from 12V to 5V at the D9 output and a 12V to 24V 10A at D10. The fan and extruder seem to work, but not the hotend. Above all, I would have to find a solution for the 12V extruder with a 24V power source, wouldn't I?

You cannot generate 24V 10A from a power supply with 12V 8A

Power is fixed

12v 8A = 96watts

so 96watts at 24v = 4A amps. (assuming perfect conversion)

but you only need 1.66A at 24V for a 40watt heater cartridge, so this should work.