1. Lower the build plate. Select 10.0mm as the Move Steps and lower the build plate to 250mm.
2. Unload the filament and remove the filament and the filament guide tubes from the printhead.
3. In the “Home” tab, set the nozzle temperatures to 0℃ and wait for the nozzles to reach ambient room temperature. Then, shut off power to the printer using the rocker switch located at the rear of the machine.
4. With the printer powered off, remove the two retaining screws from the model cooling fan using the 2.5mm hex wrench.
5. Loosen the 4 set screws, using a 1.5mm hex wrench, inside the heating block.
6. Loosen the clamping screw, marked in red, using a 2.5mm hex wrench. Remove the hotend from the shifting assembly. Carefully extract the heating rod and thermocouple from the hotend.
7. Remove the two black screws from the backing cover and remove the cover from the printhead.
8. Carefully cut the zip-tie cables. Do not cut any electrical wires, which could damage the printer.
9. Remove the two hex screws securing the Extruder Connection Board to the printhead. The bottom screw is M2.5 and the upper screw is M3.
10. Remove the heating rod and thermocouple wiring from their respective screw terminals, marked below, by loosening the screws using a flathead screwdriver.
11. Insert the cables of the replacement heating rod into the appropriate terminal and tighten the screws to securely clamp the wires. The heating rod wires have no wiring polarity requirement.
12. Ensure that there are no exposed wires touching, as it may damage the printer when energized.
13. Insert the cables of the thermocouple into their appropriate locations on the terminal and tighten the screws to securely clamp the wires. The red wire should be inserted into the positive port, and the white wire should be inserted into the negative port.
14. Ensure that there are no exposed wires touching, as it may damage the printer when energized.
15. Verify the correct installation of the polarized wiring of the thermocouple before proceeding.
16. Attach the Extruder Connection Board to the board holder and onto the printhead.
Note: The bottom screw is M2.5 and the upper one is M3.
17. Insert the heating rod all the way into the lower hole of the heater block until it extends out of the front, roughly 3mm. Temporarily fasten one of the set screws, the position will be adjusted after the next step.
18. Insert the thermocouple all the way into the upper hole of the heater block, until it bottoms out. Fasten the two set screws. Then, loosen the heating rod set screw and slide the rod back out until it contacts the thermocouple shoulder. Fasten the heating rod set screws to secure the component.
19. Insert the hotend back into the collar, onto the shifting assembly, and push upward until the upper surface of the heatsink touches the collar. Tighten the hex screw, marked in the red box, to securely clamp the components.
20. Reinstall the side model cooling fan and spacer, using the 2.5mm hex wrench.
21. Bind the cables together with zip-ties and return the back cover to the printhead, concealing the cables. It is important that cables are not pinched during this process, which could damage the printer.
22. After reinstalling the hotend, the nozzle height needs to be recalibrated. Please refer to How to Calibrate the Nozzle Height.
[13.031-EN.2.0.20240329-Pro2 Series-How to Replace the Thermocouple and Heating Rod]
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