Kobra S1 Combo TL5210 - bed is jammed against nozzle and keeps trying to go up – Electus Distribution

Issue

When Homing, your Kobra S1 Combo TL5210 print bed raises up and hits the nozzle. It makes a repeating noise and keeps trying to raise the print bed until you switch off the printer.

Cause

The nozzle is mounted on an aluminium bracket that has a strain gauge meant to calibrate the Z-height.

Either the strain gauge or the printer head adapter plate PCB it is connected to has failed, or it has a loose plug / damaged cable, so the printer does not receive the sensor info it needs to tell it that the bed has reached the nozzle.

Fix

Dismantle the covers from the print head, following steps 1 & 2 from this page.

Check that the plug on the bottom-right of the back plate below is seated firmly and the cable is not damaged.

You can trace the strain gauge cable (red/white/black/yellow) from the bottom-right plug on the PCB to the gauge on the front. Avoid touching the PCB with your fingers.

If the plug and cable are OK, get a new strain gauge assembly, and replace it. See here for details.

If this does not solve the issue, you will need a new print head adapter plate PCB. See here for details.

Note: do not attempt to Home the printer without the fan cover clipped on the hot-end. It presses the cover against a limit switch in the left-front when Homing, and will make a loud racket if the cover doesn't hit the switch.