Wiring of the MOSFET inside the Rambo-box

We designed an innovative Rambo box for Zaribo 220 and 320 which holds the Rambo board and a standalone mofset board for the heated bed.

Important: In this tutorial hotend cables were replaced with 14AWG silicone cables optionally. Please don’t get confused, there is no need to replace hotend cables, you can connect your hotend to its place on the Rambo Mini board as usual. 

In another tutorial,  the principle ideas and reasons for using a MOSFET have been discussed. For the Zaribo a Rambobox was designed that can act as housing for a MOSFET as well. In this little tutorial I was describe how it is wired.

There is a simple way where the heated bed is directly connected to the MOSFET. And the is an alternative way where the heated bed is connected to the WAGO terminals. The latter way is maybe a little more convenient when the heated bed needs to be removed, e.g. for replaceing the PEI sheet. In the end it’s a matter of taste which way one prefers.

Tools needed:

  • Screw diver
  • Allen key 2,5mm
  • Cutter
  • Crimping tool
  • Wire stripper

Electrical and other parts needed

  • Rambo mini 1.3
  • MOSFET
  • 4 Terminal connectors
  • 8 Socket Head Cap Screw M3 x 4mm
  • 6 Gray insulated ferrules
  • 2 Brown insulated ferrules (not white as in the picture)
  • Black and red AWG 14 wire
  • 2 WAGO terminals (optional 2 more)

Use the socket head cap screws to gently fasten the Rambo board and MOSFET into the Rambo box. Clip in two of the WAGO terminals as well.

Start with the preparation of the four cables from the PSU. Strip off the insulation on all four of them. Then connect the cables from the PSU, one pair of cables goes to the MOSFET. Make sure the cables are fatened tight with the screws. The other pair goes to two WAGO terminals. Lift a lever of the terminal, slide in the cable and close the lever.

The next step is to prepare two pairs of cables for the power supply of the Rambo board. Take two red and two black cables about 10cm long each. Strip off the insulation on all, crimp the grey ferrules to the ends and add a terminal connector. The process is shown in the picture on the right .You may have to cut the tip of the ferrules after crimping for proper fitting into the connector. Note that you need two pairs.  Make sure that the red cables (+) is always on the right of the connector!

Now plug the terminal connector into the Rambo board. Shorten cables if necessary to connect them to the WAGO terminals. Again strip off the insulation before connecting.

In order to switch the MOSFET on / off we have to connect the little white cable to the output of the Rambo board. Cut the white cable to length, strip off the insulation and crimp the brown insulated ferrules to them. Now connect the terminal connector to the crimped cable. The order of cables in the connector does not play role, since the cable connects only the switch. Plug the terminal connector into the right connector at the bottom of the Rambo board.

Now we are almost done. Connect the heated bed as shown in the picture on the right to the MOSFET. Take of the terminal connector when you have one on the cables, no crimping is needed. The cable for the hot end is connected to the right terminal connector at the bottom of the board. The cables go to the top of the box. Done.

Instead of connecting the heated bed to the MOSFET it might better to connect it to WAGO terminals. This makes life easier for the process of removing the bed for changing the PEI sheet. Insert two more WAGO terminal into the Rambo box. Connect the heated bed to the WAGO terminals. Then prepare two short cables to connect the output of MOSFET to the WAGO just installed. Just remove insulation, no crimping needed.

Next time you just have to lift the levers of the WAGO terminals to release the cables of the heated bed. One more tip: closing the levers is easy when using a small Allen key to pull them down.

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