MIN TEMP FIXED - can't find cause...
About a week ago, I had a print detach overnight and blob the hot end badly. I cleaned it by heating and letting everything melt off then carefully removed what remained. I knew I may damage the thermistor and heater wires as they were encased in PLA, so I ordered a complete replacement assembled hot end. I continued to run the printer and had no issues until today when I started to get MIN TEMP FIXED errors. This was on the screen, and it said to reset and try again. It does not continue the print after reset.
So I figured the thermistor wires were damaged and replaced the hot end assembly. I ran the complete setup calibration process including PID tuning and still got the same error, though at a different point in the same print. I updated to the firmware that was released today and re-ran the setup including PID tuning again. Still got the same error at a different point. I checked the resistance of the thermistor on both the old and new hot end and it checked good. I also checked the board connection by switching the heat bed and hot end thermistors as stated in the official troubleshooting guide and the error switched to MIN BED TEMP which shows the board connection is good.
Is it possible that the GCODE or STL has an error that is causing this? I tried slicing the same STL on a PC instead of my usual Mac, onto a different SD card that was freshly formatted and contained only one file. But I still get the error.
RE: MIN TEMP FIXED - can't find cause...
intermittent or loose thermistor wiring or plug
RE: MIN TEMP FIXED - can't find cause...
Thanks David, but I switched the thermistor and plug already, same issue.
RE: MIN TEMP FIXED - can't find cause...
So I posted the file here in case anyone wants to try it out - I don't understand how a file could mess with the RAMBo and cause a MIN TEMP error, but it's only happening with this specific model.
https://www.prusaprinters.org/prints/5499-min-temp-error-test-mavic-2-battery-dock
RE: MIN TEMP FIXED - can't find cause...
There's nothing suspect in the gcode ... temp wise anyway ... you can rule that out. Have you checked for crashes detected? The part has a few spots where curl can happen that could cause a snag. And if you removed any of the screws in the extruder when working on the hot end, you might have introduced some bearing drag (loosen the read case screws near the bearings to allow them a bit more freedom). Anything that might cause a short pause and automatic restore might cause the nozzle to lag too far behind a set point. A photo of a failed part might be informative.
RE: MIN TEMP FIXED - can't find cause...
I tried rotating the part 90 degrees in the slicer and it printed fine 🧐 then tried the original orientation and it gave the error again. I can't figure this one out. Any help from someone more experienced than myself would be greatly appreciated.
RE: MIN TEMP FIXED - can't find cause...
There's nothing suspect in the gcode ... temp wise anyway ... you can rule that out. Have you checked for crashes detected? The part has a few spots where curl can happen that could cause a snag. And if you removed any of the screws in the extruder when working on the hot end, you might have introduced some bearing drag (loosen the read case screws near the bearings to allow them a bit more freedom). Anything that might cause a short pause and automatic restore might cause the nozzle to lag too far behind a set point. A photo of a failed part might be informative.
Hi Tim, there are no crashes detected and the part doesn't get printed enough to curl - it errors out usually on the first layer. I'm not sure what screws you're indicating.
RE: MIN TEMP FIXED - can't find cause...
Why is the bed at 83c ? Are you printing PET or ABS?
With the error changing when you swap connectors, it sounds more like a hardware problem (bad thermistor).
RE: MIN TEMP FIXED - can't find cause...
Yes, printing in PET. Bed temp set at 85.
RE: MIN TEMP FIXED - can't find cause...
The error didn't start with my changing the hot end, it started before. I changed the hot end with the hope it would fix the error.
RE: MIN TEMP FIXED - can't find cause...
Could be the Einsy side that failed ...
You also say you only see this with this one single gcode, and it always fails right at the X?
RE: MIN TEMP FIXED - can't find cause...
Could be the Einsy side that failed ...
You also say you only see this with this one single gcode, and it always fails right at the X?
That little blob is just where the hot end stopped at the error. It doesn't happen at the same point every time.
RE: MIN TEMP FIXED - can't find cause...
You might explore this thread:
https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-prusa-i3-kit-archive/err-mintemp-solved/
RE: MIN TEMP FIXED - can't find cause...
Solved with the help of this forum, Prusa chat and YouTube.
Ended up being a sporadic wire failure for the heat bed thermistor. The error showed MIN TEMP, so I assumed that was referring to the hot end thermistor, not the bed thermistor, which should have read MIN TEMP BED. When it resolves itself, it should show MIN TEMP BED FIXED instead of MIN TEMP FIXED.
I had initially measured the resistance on the heat bed thermistor and it tested good. I tested again, this time moving the bed back and forth slowly and found the resistance to flicker during some extreme movements. I replaced the thermistor wiring and it seems to have solved the problem. Why it was failing on this particular print seems to be just a peculiarity of how the bed was moving (though I printed much larger models successfully). But considering I have something like 400 days of print time on this printer it seems logical that the wiring is wearing out.