Thermal runaway protection is not working

[alexeypodrezov]

I've just discovered an issue with picobilical frame which is very concerning. I often leave my printer to print at night, and today I've discovered it at the morning with half-finished print with burned to black plastic at the point where nozzle were touching the model. Turns out transistor, which controls hotend has burned down and picobilical were sending signal to heat it to maximum even if klipper was trying to turn it off When electronic component is getting faulty, hotend should not be heating to the maximum - this is serious flaw which might create a disaster for someone else!

[suedyx]

Hello Alexey @alexeypodrezov ,

It's Sue from LDO SUPPORT TEAM. Sorry for this concerning issue happening. Could you throw an email to sue.xiong@ldomotors.com with some pictures of the Frame PCB if you happened to take and your kit# that is engraved on a metal tag? Issues like this always attract more attention from us and we hope our customers stay safe. Thank you.

Best Regards, Sue LDO SUPPORT TEAM

[alexeypodrezov]

@suedyx , I sent an email with photos four days ago and haven't received any answer yet Meanwhile, I replaced the faulty transistor, and the printer is working again, even though I'm afraid to leave it working without my constant attention, expecting a workaround here.

[meistertek]

Has this issue been replicated at LDO with testing? I would think that a firmware update would address this issue, or does it require a hardware revision? Has this issue been addressed? For now would it be possible to skip the frame pcb and run the heater directly from the mainboard mosfet?

[jamestattersall]

I have has the same thermal runaway. Extruder heater on max whenever system is powered up. Klipper detects heater temperature exceeding max and shuts down, but heater continues to run as long as system is powered up. Constant 24v on toolhead heater power pin. Attached photo shows PCB and MOSFET with their IDs.