Consistent hotend temperature offset
Hey folks!
Some rubber ducking, some troubleshooting here...
On my VCore 3.1 that I recently put back together, I have an issue with my hotend thermistor readings.
I'm using the latest RatOS build (2.x), Octopus board, EBB42. I started using the Rapido hotend with their stock thermistor, and had a reading of about 6 degrees instead of the room's 21. I changed the hotend for a mosquito, with another type of thermistor, and had the exact same reading.
I had to change the Octopus board, so I'm left with a potential faulty EBB42 (pullup resistor?).
I was unable to fix it in the software (the new config is more plug'n'play, but less easy to tweak) so I ended up modifying the filament needed temp in the slicer.
I'd appreciate some of your thoughts on this, I'm waiting for a new EBB42.
Thanks a lot!
11 Replies
Hello
so you mind to share your config files?
and RatOS 2.X is not the latest image.
2.1 Rc2 (updatable to Rc3) is.
Hey! Thanks for jumping in 😄 I should have been more precise, you are right!
I'm on the 2.1 RC3, all is up to date.
I don't know if that helps, but I didn't see this issue when I was with RatOS 1. But I also rebuilt the printhead, so I might have damaged the EBB.
The thermistor is an NTC 100K
IIRC there isn't a pullup resistor for the thermistors as they are a variable resistor and a pullup would throw them off
I see in the RatOS.cfg this line:
sensor_type: NTC 100K MGB18-104F39050L32
Is there a different NTC100K selectable in the configurator to try?That's all there is. I ran with the ATC before, when I had the rapido, but had the same discrepancies on the readings.
This is why I think the problem is either the EBB42 or software.
But since there is not a pullup resistor, and since the problem appeared with RatOS 2, it might be a conf issue, yes.
For the record, I already re-installed the whole OS, without any improvement.
Does the thermistor show a different reading if you het it up, like with a heat gun or lighter?
The usual causes of thermistor issues is a short or an open. For it to read something in the middle but inaccurate is unusual
It shows a proper reading, just with an offset. I can print well if I lower the filament temperature by 15deg or so.
If I heat the thermistor, I have a different reading, yes.
Basically, my sensor is on the B option:
Some rapidos came with a faulty thermiator that read wrong just like yours. You can compensate by setting your temp lower like you found, or replace it
I changed my rapido to a mosquito, exact same readings 🙈.
okay, THAT is weird. Was there any connectors or wiring in common?