With my new Tecto hot-end upgrade, I just had a case where the temp readout was steady at 27degC but the hot-end was pushing almost 300degC!! I wasn’t really paying close attention when the nozzle started smoking. I immediately stopped preheat and began pushing the filament through manually to bring the temp down fast and prevent nozzle clog/burnout. The filament was getting vaporized! Anyway, I am at a loss as to what exactly happened. Once cool and I restarted the printer the temp readout was fine and a test preheat went fine, I monitored with a handheld thermocouple probe.

Then again, I did some more tests while Simplify3D Control Panel was graphing temps and it happened again. see attached pic. The purple line is the nozzle temp measured by sailfish, the red line I drew is approx what my handheld probe showed. You can see where the temp was about 30degC up to sample #10, then spiked to 125. So while the actual temp was about 150, the readout was frozen.

I would suspect the TC is getting grounded but these are supposed to be ungrounded TCs on the Tecto hot-ends *and* I tested again with a continuity tester and there is no connection to the TC case (though I tested cool). I’ve confirmed there is nothing pinching the TC cables back to the Mightyboard.

Tecto Hot-Ends

https://shop.raffle.ch/shop/tecto-heater-block/

Any ideas?

I have not used Sailfish much but installed it after doing latest maintenance on my Rep 2X. I replaced my hot-ends with the Raffle.ch Tecto’s with the upgraded thermocouples. I do love the new TCs, they are bullets like the heat cartridge instead of the flimsy screw in type.
tectotempfail.png

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The noise in your chart suggests an electrical problem to me. Have you measured the voltage across the thermocouple and compared that to a reference chart for the type of thermocouple you are using? If it seems good, you can then use two resistors as a voltage divider and check that the thermocouple voltage sense measurement is working correctly and is stable.

Hello,

I believe that your thermistor is going out of its box. So the temperature sending to the board is the temperature of the room and the board is trying to heat…the room!! I got that problem.

Take a look to the thermistor.

Best regards.

had the same problem I tested the TC and Cartrage heater on my other printer no Spikes or problems. you might have to update the firmware… All I do is reinstall Sprinter. even using the Voltage limitation feature did not solve my problem I suspect the Arduino Mega he RAMPS shell has a Short causing the problem I have not ryed Isolating the MOS’s they may be sorting out causing the problems. because putting any power to them causes the same problem.