¶ Heatbed Sensor Unit / Heatbed Piezo Interface Board
A sensor unit is a device capable of detecting force signals and converting them into usable output electrical signals according to specific rules. To monitor the surface pressure of the heat bed, 3 ceramic force sensors are installed on the underside of the heat bed.
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There are 2 small circuit boards called the heatbed piezo interface boards, which are installed inside the heatbed. Heatbed sensor 1 and heatbed sensor 3 are connected to these boards.
¶ When to use
If the following three conditions are met simultaneously, or if there is obvious physical damage to the sensor, you need to replace the sensor:
1. You receive an error message stating, "The sensitivity of heat bed force sensor 1/2/3 is too low. The electronic connection to the sensor may be broken."
2. You have followed the HMS guide for troubleshooting but have not resolved the issue.
3. The service team has approved the replacement.
¶ Tools and materials required
- New sensor unit / New heatbed piezo interface board
- H2.0 /H1.5 Allen key
¶ Safety warning and Machine state before starting operation
Please carefully follow the steps outlined in this guide to perform the replacement. Ensure the machine is powered OFF before starting any disassembly and assembly procedures.
¶ Operational guide
We will use sensor 1 and the heatbed piezo interface board as examples in this replacement guide, but the process for replacing the other 2 sensors and the other heatbed piezo interface board is similar.
¶ Step 1 - Create space for the replacement
Power ON the printer and navigate to the movement menu on the LCD screen. Adjust the Z position of the heat bed to the middle. Once done, power OFF the printer, remove the top glass cover plate, and then move the toolhead to the excess chute.
¶ Step 2 - Remove the protective cover
The protective cover is secured by 4 buckles. Unlock one side first, then the other, to remove it.
¶ Step 3 - Remove the heat bed pretension nuts
Unscrew the 3 pretension nuts to release the heat bed from the metal bracket. Note that each nut also has a rubber ring on top.
¶ Step 4 - Open and temporarily prop up the heat bed
Open the heat bed carefully due to the cable inside and remove the loose pretension springs. To proceed with the procedure, temporarily support the heat bed. You can use a block to support the upper part of the heat bed (see picture below).
¶ Step 5 Remove the heatbed piezo interface board
Now, disconnect the 2 connecting cables from the heatbed piezo interface board, then remove the 2 screws and take out the board.
¶ Step 6 - Remove the sensor unit
Unscrew the 2 screws on the bottom, and remove the sensor with the holder.
¶ Step 7 - Install the sensor unit
Prepare the new sensor for installation. Note that there are 2 limit posts to help ease the installation (see picture below). Secure the sensor in place by tightening the 2 screws.
¶ Step 5 Install the heatbed piezo interface board
Install the heatbed piezo interface board on the bracket, lock in the 2 screws, and connect the 2 cables.
¶ Step 9 - Install the pretension springs
Hold the upper part of the heat bed and remove the support block you just used. Install the pretension springs to the heat bed screws one after another. In general, you only need to install the front two springs, because the rear one will not fall off.
Hold the upper part of the heat bed and remove the support block. Proceed to install the pretension springs onto the heat bed screws one by one. Typically, you only need to install the front two springs, as the rear one should remain in place.
¶ Step 10 - Mount the heat bed
Now you can close the heat bed and mount them together. Gently press from the top of the heat bed to ensure that all three stubs can pass through the holes on the sensor holder.
¶ Step 11 - Lock the pretension nuts
Place the rubber ring onto the 3 pretension nuts and then screw them in evenly, a little at a time. DO NOT lock them yet. Continue to screw in the nuts evenly, until the studs are flush with the bottom of the nuts (see picture below).
¶ Step 12 - Install the protective cover
Now, reinstall the protective cover. Similar to the removal process, start by installing one side first, and then proceed to the other side.
¶ How to verify completion/success
Connect the power cord and power on the printer.
Ensure the chamber is clear of any prints or extrusions on the bed. Navigate to the settings menu on the LCD screen, select the Calibration tab, and press “Start Calibration.”
If everything proceeded as expected, and no errors or warnings occurred during the calibration, the replacement was successful. Otherwise, double-check the connections and retry. If issues persist, please contact the service team for further assistance.