Solved Reported temp of cold hotend is 15º above ambient.

[Telescopic]

Printer Model

LDO Voron 0.2

Extruder Type

Clockwork 2

Mainsail is reporting an extruder temperature ~15º above ambient on a just-powered up, cold machine.

The hotend is a stock Revo Voron 40w with the usual 104NT-4-R025H42G thermistor.

The toolhead is an EBB36, connected by USB to the RPi.

Up-to-date Danger Klipper.

The extruder has no trouble reaching an (indicated) temperature and stabilizing, but if I then turn off the heating, it will cool down to (again) about 15º above ambient.

Any ideas?

 

[NoGuru]

Bad thermistor or wire. Probably okay if you know you have to compensate for the difference.

 

[erik.zweigle]

Make sure the jumper is not installed which would mislead Klipper into believing you have a PT1000 on the board instead of 104NT. In your printer.cfg file ensure that thermistor heading includes

pullup_resistor: 4700

somewhere beneath it. Or 2200, I forget which value resistor is needed to report the correct value. Just try both.

 

[Telescopic]

Make sure the jumper is not installed which would mislead Klipper into believing you have a PT1000 on the board instead of 104NT. In your printer.cfg file ensure that thermistor heading includes

pullup_resistor: 4700

somewhere beneath it. Or 2200, I forget which value resistor is needed to report the correct value. Just try both.

No jumper for PT1000.

EBB36 doc says if you're using a 104NT, the pullup resistor is 4700. Ah, but my config says 2200.

Fixed. Thank you, Erik.

 

[Telescopic]

Bad thermistor or wire. Probably okay if you know you have to compensate for the difference.

Yeah, but since this is a new build I'm going to resolve it. Turns out I had an incorrect pullup resistor value in the config.