Firstly it is very possible to run your RAMPS on 24 volts, but there are some caveats you have to be aware of.
Many people want to run their RAMPS on 24 volts, but there are several different expectations. This will hopefully document all options.
The ramps is actually two boards on one PCB
The first part is the majority of the board. It provides a fuse, power and sockets for Stepper drivers, MOSFETs for Hotends and fans and a assortment of other connectors and discreet components for thermistors and end stops etc.
The second part is just for the Heated bed, with its own fuse, power socket and MOSFET
This is why the RAMPS power connector has 4 wires.
The top two 11amp power wires are for the heated bed only.
The bottom two 5amp power wires are for the first part of the board, the fans, the MOFETS, the hotend and the stepper drivers and everything else.
Modifying for 24v heated bed
You have to replace the 11 amp polyfuse, MF-R1100, with something else. This device is only rated for 16v. It will burn out and catch fire on 24volts. Most simply replace the polyfuse with a thick wire. Then wire in a 24v fuse with a inline fuse holder on the heated bed cables. Wire up 24 volt supply to the top two 11amp power sockets and its completed.
You can also use an external MOSFET with a separate 24v supply without any changes.
Modifying for 24v hotend, fans and Stepper Drivers
This you have to be more careful of.
NB The 5 amp side also powers the mega, via the diode D1. Do not feed this with more that 12 volts. The on board voltage regulator on the mega2560 board will over heat and die.
First step is to work out how you are going to power the mega2560. There are several options.
- Remove D1, power the mega via the 2.1mm center-positive DC jack, The recommended range is 7 to 12 volts.
- Remove D1, and power mega2560 via the USB cable. You must leave whatever its connected to on or the mega will power down.
- You can use a special mega2560 that is designed to take 24v an example is the Taurino Power. It just plugs in, do not remove D1.
- Use some sort of external 5v regulator. you still need to remove D1, then plug the 5v into any unused 5v pin of the RAMPS. Most people use an unused end stop plug as these have 5v and GND handy.
Secondly you need to check the capacitors under the stepper drivers. These need to be 32 volt, cheaper RAMPS will have 16 volt capacitors and these cannot be used without replacing the capacitors.
Lastly wire in 24 volt into the +v pin and GND into the GND pin of the 5amp power plug.
NB You also must use 24volt fans and 24v heater cartage for you hotend as these are all tied together. Some people chose to still use 12v fans and hot end heated cartridges, by adding in 24v to 12v converters before the fan and the heater cartage.
Modifying just the stepper drivers for 24v
Each stepper driver has a VMOT and GND pin just next to the VMOT pin. If you remove these pins from the modules and face them pointing up in stead of down into the socket, you can wire these directly to a 24v source.