How to replace the silver PSU with the black PSU

Relevant for:

MK4 MK3.9 MK4S MK3.9S

Last updated 2 months ago

Difficulty

Easy

Steps

Available languages

Step 1 Introduction

⬢This guide will take you throught the replacement of the silver PSU (Power Supply Unit) with the black PSU on your Original Prusa printer.

The following instructions are provided as an extension to preparation for the MK3.9/S upgrade and MK4/S upgrade.

Do not start disassembling anything on the printer! Wait for instructions.

⬢Before you start disassembling the printer, make sure you have received the black PSU 24V 240W from Prusa Research.

Keep the PSU aside, we will need it later on.

Step 2 Tools necessary for this guide

⬢For this chapter, please prepare:

⬢2.5mm Allen key

⬢3.0mm Allen key

Step 3 Removing the silver PSU

⬢Release two M3 screws securing the PSU in the extrusion.

⬢Release two M4 dome head screws securing the PSU to the frame.

⬢Remove the PSU from the frame.

Keep all removed screws. You will need them again.

Step 4 Repositioning the M3nE nuts

⬢Release eight screws securing the rear plate.

⬢Remove the rear plate from the frame.

Keep it aside, you will need the part in the following step.

⬢Slide two M3nE nuts from the short extrusion.

⬢Insert the removed M3nE nuts into the "outer" side of the short extrusion.

The exact position doesn't matter at this point. We will adjust it later.

Step 5 Assembling the rear plate

⬢Ensure the frame with shorter extrusions is rotated towards you.

⬢Place the rear plate on the extrusions and secure it with M5x16r screws, DON'T TIGHTEN them yet!

Before you completely tighten all the screws, ensure that both nuts are in the extrusion.

⬢Now, tighten the screws fully, but ON A DIAGONAL, see the second picture. As soon as you finish the first, tighten the second pair. Then proceed to the second short extrusion.

Step 6 Black PSU: parts preparation (Silver PSU)

⬢For the following steps, please prepare:

⬢Black PSU 24V 240W (1x)

⬢M3x10 screw (2x) use the removed ones

⬢M4x10r screws with dome head (2x) use the removed ones

Step 7 Installing the black PSU

⬢Have a look at the right side of the frame and locate the M3nEs nuts. Insert M3x10 screws into them. Turn them only 3-4 times by using a 2.5mm Allen key, just for the screws to be kept in place.

⬢Take the PSU and place it above the screws. Adjust the M3nEs nuts so they line up with the grooves on the bottom of the PSU's case.

⬢Slide the PSU down onto the screws. Screw them in some more, but don't tighten them firmly yet - we need the PSU to be able to move slightly so we can adjust its position in the next step!

The screws should be able to hold the PSU in a "vertical" position for now.

Step 8 Securing the black PSU

⬢Now have a look at the frame from the front side. Verify the PSU is on the right back side of the frame when looking from the front.

⬢Insert M4x10r screws into the holes in the frame, towards the front of the PSU.

⬢Adjust the position of the PSU, there are holes in the PSU's case, which must align with the holes in the frame. By default the PSU sits slightly lower than needed, pull it up little bit. until the M4 screws are able to catch the thread in the PSU.

Make sure the PSU is pressed against both the frame and the extrusion on the bottom.

Everything aligned? Tighten the M4 screws up using the same 2.5mm Allen key.

⬢Now, tighten up the M3 screws on the bottom.