Thermal Runaway - hot end - Everything looks ok - now what?
I've now had two of these errors on my I3Mk3+ I have done a visual inspection and there does not appear to be anything wrong with the fans., the sensor is inserted all the way into the heat block. When I try to run small prints they work fine, the LCD screen shows the temp going up and it looks normal. Then I get the error. I am printing Prusament PETG and I have a cardboard / plastic enclosure so no sudden drafts. of cold air.
The first time I was 8 hours into a 13 hour print, temp of 240 degrees and I was not near the printer when it occurred. The second time was about 10 minutes into a 30 minute print, 250 degrees, and the fan was running. The photo shows the print, the pointer is the last place that was printed.
Is there a way of testing the sensor or any diagnostics that I could run to determine the problem?
RE: Thermal Runaway - hot end - Everything looks ok - now what?
You can test the thermistors and heaters with a multimeter.
https://help.prusa3d.com/en/article/multimeter-usage_2117
However if it is intermittent it may not be a definitive test, If the printer is under warranty I would suggest speaking to live chat on the eshop, otherwise I would replace the hotend thermistor.
Not sure if thermistor is classed as a wear part.
How old is the printer?
Tank you very much!
RE: Thermal Runaway - hot end - Everything looks ok - now what?
@clarmrrsn
The printer was purchased in late 2018, so less than three years. I also got the upgrade 3S kit two years ago, so I will ask - but kind of a maybe.
I have a multimeter but the article you sent is for testing a mini . I know the heatbed voltages are different but are these instructions correct for the hot end thermistor?
I am also not clear where the thermistor is located. Is it inside the heater block? Do I have to remove it from the heater block to get the measurement?
Thank you for your reply. I love the printer when it is working. When it isn't it becomes more of an education that I wish!
RE: Thermal Runaway - hot end - Everything looks ok - now what?
@vakil
The article relates to all models not just the mini, you dont need to remove the thermistor from the hotend to test, just unplug the cable from the board and test the contacts on the header plug. Related resistances are in the document. I would suggest replacing the thermistor anyway,if its intermittent you won't prove anything, most likely to be the thermistor, tbey dont last for ever and do fail, maybe worth ordering other spares like a heater and bed thermistor as well while you are at it., there are some spares it is worth keeping.
2 year warranty on the kit iirc, I doubt it is in warranty, but the the thermistor is not expensive, not sure on postage.
Please make sure you are confident with this repair before attempting it
https://shop.prusa3d.com/en/mk3mk3smk3s/205-hotend-thermistor-e3d.html
Tank you very much!