This guide is on replacing the Electronics Board in an Ultimaker S3.
Please ensure you are ESD safe and the printer is unplugged whenever working under the printer's bottom cover.
Gently lay your printer on its side, and remove the 4 screws, one in each corner of the bottom cover. Tilt the cover back, and unplug the speaker connection highlighted in this photo. Then remove the bottom cover.
The board has two connectors with large orange tabs on them. Press the tabs away from the connector, towards the center of the board, and remove the black/red (Power) wires, and the two white(Heater) wires.
Remove the printhead cable by pressing the locking tab and pulling on the cable.
Remove the antenna from the WiFi board, be careful not to damage the antenna.
Unplug all remaining connections
Undo each highlighted screw, and remove the board from the printer.
There are two thermal pads under the board, please set these aside for now, as they will go back in with the new board.
Press the pads onto the board where indicated. Position the Electronics Board over the screw holes, and reinsert the screws according to the prior photo
To begin connecting the new board, secure the WiFi antenna to the card, on the port with the filled in black triangle beside an “M”.
Connect rest of the cables as shown in the picture above. The motor cables are labelled to indicate which port should be used, and the end stops are color coded.
Now Connect the Ethernet cable, Controller USB, Camera USB, and HDMI to the board. The Camera USB has a white cable, and the Controller USB has a black cable.
Check that all wires and connectors are plugged in according to the pictures.
Now reinsert the two larger white wires into the connector with orange tabs on the printhead cable side of the board. Once the wires are fully seated, push the orange levers shut to secure them. Repeat this process with the red and black wires and connector on the opposite side.
Position the bottom cover with the speaker towards the front of the printer. Reconnect the speaker to the board