How to replace a hotend heater (MK3S/MK3S+)

Relevant for:

MK3S MK3S+

Last updated 3 years ago

Difficulty

Easy

Steps

Available languages

Step 1 Introduction

⬢This guide will take you through the replacement of the hotend heater on the Original Prusa i3 MK3S and MK3S+.

Some parts might slightly differ. However, it does not affect the procedure.

⬢All necessary parts are available in our eshop prusa3d.com.

Note that you have to be logged in to have access to the spare parts section.

Step 2 Tools necessary for this guide

⬢For this guide, please prepare:

⬢2.0 mm Allen key

⬢2.5 mm Allen key

⬢Needle-nose pliers

⬢Flat screwdriver tip width 2.5 mm (3/32")

⬢Cloth or piece of fabric 15x15cm

Step 3 Preparing the printer

Turn the printer off and unplug it!

⬢Before you proceed, it is recommended to protect the heatbed.

⬢Take off the flexible steel sheet.

⬢Use any cloth or piece of fabric, which is thick enough and cover the heatbed. This will ensure you won't damage (scratch) the surface during the disassembly.

Step 4 Opening the electronics box

⬢Release the M3x40 screw in the Einsy case. No need to remove them.

⬢Open the Einsy-doors.

Step 5 Disconnecting the hotend heater

⬢Cut the two zip ties on the cable bundle. Avoid cutting the cables!

⬢Release two screws on the cable clip and remove the clip.

⬢Disconnect the hotend heater cable from the Einsy electronics board.

Step 6 Removing the textile sleeve

⬢Remove the textile sleeve from the cable bundle from the Einsy case to the cable-holder on the extruder.

⬢Cut the two lower zip ties on the cable holder. Avoid cutting the cables.

Do not cut the upper three zip ties.

⬢If you have a zip tie on the heater cable and the thermistor cable, carefully cut it off.

Step 7 Removing the heater

⬢Using the 2mm Allen key, loosen the black round head screw on the underside of the heaterblock. No need to release the screw completely.

⬢Using the Allen key gently push the hotend heater out of the heaterblock.

Step 8 Removing the connector

⬢Remove the hotend heater completely from the printer and put it aside.

⬢Using the flat screwdriver, loosen both screws in the connector. No need to remove them completely.

⬢Pull out both wires from the connector.

Do not throw the connector away. We will use it again later.

Step 9 New hotend heater: parts preparation

⬢For the following steps, please prepare:

⬢New hotend heater (1x)

⬢Molex connector (1x) reused from the old heater or if damaged, buy a new one in our eshop.

⬢Zip tie (2x)

WARNING: Be very careful with the hotend wires, handle them with care.

Step 10 Assembling the new heater

⬢Insert both heater cables all the way into the Molex connector. The order of the cables doesn't matter.

⬢Tighten two screws on the connector by the flat screwdriver.

Make sure the cables are fully inserted and tightened, this is very crucial!

Step 11 Installing the new hotend heater

⬢Insert the new hotend heater into the heaterblock from the left side of the extruder (hotend fan side).

⬢Adjust the hotend heater so that the wires don't cross, but rather go parallel one above another. See the second picture.

⬢Center the heater so it sits in the middle of the heaterblock.

⬢Hold the heater cables with one hand so that they keep pointing towards the back of the extruder (X-carriage).
Using your other hand, carefully tighten the black round screw on the underside of the heaterblock.

After fixing the heater in place, it does not matter if the cables hang down slightly for a while. But do not pull on them! We will soon arrange them into a final position.

Step 12 Guiding the hotend thermistor cables

⬢Make sure the hotend thermistor cables (thinner pair) are going above the heater cables. If not, guide them according to the picture.

Guiding the thermistor cables below the heater cables may cause issues later.

Step 13 Tightening the textile sleeve

⬢Use two zip ties and push them through the upper slots on the cable-holder.

⬢ATTENTION! Before tightening the zip ties add the cables from the hotend. Use the channel in the printed part to arrange them properly.

⬢Once the hotend cables are included, tighten the zip ties and cut the remaining parts.

⬢Open the textile sleeve and insert the cables from the hotend.

⬢Compare the look of the cable management with the last picture.

Step 14 Guiding the textile sleeve

⬢Wrap the entire length of the sleeve around the cable bundle.

⬢Using your fingers gently twist the sleeve (not the cables) and create several wraps. This will prevent the cables inside to slip out during the printing.

⬢Twisting the sleeve will effectively shorten its length, so then the nylon filament inside the cable bundle can easily reach the hole in the plastic electronics box (Einsy-base).

⬢Push the nylon filament into the hole in the plastic cable clip on the einsy-base.

Ensure the nylon filament isn't pushing the motor cables and if needed slightly unwrap the sleeve and push the filament up.

⬢Slide the sleeve in the holder at least 3/4 of the holder's height.

⬢Use the Extruder-cable-clip and two M3x10 screws to fix the cable bundle in place.