TAZ Workhorse Pushing Bed Down

I inherited responsibility for our TAZ Workhorse here at work. It had sat for a couple years unused until someone tried to print on it and found it wasn’t working correctly. After they came to me, I started checking everything I could and noticed the tool head itself was covered in melted plastic. Found several posts about checking the toolhead with a multimeter and so I did. Found out that the plastic coating was preventing the toolhead from properly homing. Tried cleaning it some but ultimately decided to order a new toolhead since I wanted to go with a harder nozzle anyways.

Fast forward to this week and I get the tool head successfully installed. The multimeter test shows a 0.7-0.8 reading when touching the nozzle and the zero sense wire on the right. I then verified Cura was up to date and using the correct tool head, followed by updating the firmware to the latest available.

Now when I try to Auto-calibrate the printer or do any sort of leveling, it will move to the first washer at the front right of the printer and proceed to push the corner down and torquing the bed. Will also do that to the calibration cube near that washer.

I’m at a loss as to what to check next and any advice would be greatly appreciated.

Check between the zero sense wire and the connection to the board. It’s a simple circuit, you probably just have a break. No idea on what they tried to do two years ago, so verify both wires.

Thank you for the quick response last night. Wasn’t able to tackle it until this afternoon.

Found the issue in the last bit of wiring that attaches the ground to the bed. Looks like the bed extension harness went bad. I’m guessing something happened to the diode.

Now to figure out how to fix this since I can’t seem to find a replacement on the Lulzbot store. I did locate the spec and diagram though. :slight_smile:

Thanks again!