Centauri Carbon 2 series - Error 803 - heats too much

Issue

Your Centauri Carbon 2 3D printer shows a message "Error 803" after startup. The nozzle may also heat up too much, and does not stop at the set temperature. From switch on, you may see the temp on the nozzle start to climb above 100 degrees - turn it off if you see this.

Cause

The Extruder Communication board (Cat no. 002010) at the back of the print head needs to be replaced.

How to Fix

Overview of the process is here. 

If your nozzle does not heat uncontrollably on switch-on: 

Send the heated bed platform to the lowest position (On the Display: Prepare -> 30mm -> Z down).

Now turn the printer off

If your nozzle does heats up immediately on switch-on: 

Leave the printer off

Turn the two jack screws at the front anticlockwise by hand to move the plate down a bit

You need a large enough gap to fit your 2mm wrench underneath the bottom hotend PCB

Unscrew the two 1.5mm bolts on top of the extruder USB data cable, and lift the cable up.

Unscrew the three 2mm bolts on the print head back cover.

Unplug the three cables on the Extruder Communication board. The top one has a clip you need to press, the others just pull out. Grip the plugs with a tweezer in preference to pulling on the cable.

Unscrew the 2mm bolt holding the Nozzle Heating Interface board underneath the print head.

Gently pull the Nozzle Heating Interface board straight down to disengage the 8 pins that hold it to the Extruder Communication board. Don't pull too far, as there are cables from the hot end attached to it. 

Unscrew the three Philips-head screws from the Extruder Communication board.

Pull the board outward from the bottom, then downward to disengage the USB socket from the top slot.

Install a new Extruder Communication board and reassemble as a reverse of the above steps. Avoid touching the exposed components on the board with your fingers.

Be careful as you push the Extruder Communication board into place that you do not damage the blue-red-green motor cable - it needs to be gently pulled through the hole as you press the board back, so it is not trapped under the board.

Carefully align the 8-pin connector on the Nozzle Heating Interface board before pushing the board up.