HELP: Weird Temp Issues

[tracetheory]

All of a sudden when I try and start a print, after 10 seconds after starting the first layer the extruder temp flashes a negative number quick than goes undefined, BUT it will preheat at those same temps for a long time without erroring...

my printer had a melzi 2.0 red board in it

video: https://photos.app.goo.gl/wKOcFyhE5CVSAzlM2

[Roberts_Clif]

It sound like your thermister is shorting out on the Heater Block. The thermister should be pushed all the way into the temp hole, including the Teflon thermal tubing.
Each Teflon tubing should be placed one on both sides if the retainer screw with washer, forming a Y around the retainer screw. This keeps the thermister in place without shorting out.

[tracetheory]

It sound like your thermister is shorting out on the Heater Block. The thermister should be pushed all the way into the temp hole, including the Teflon thermal tubing.
Each Teflon tubing should be placed one on both sides if the retainer screw with washer, forming a Y around the retainer screw. This keeps the thermister in place without shorting out.

You're right, it was shorting out! I got a weird one that is kind of cemented in place, will have to replace the block. Thank you!

[Whork9999]

thanks guys a lot! i've been having the same problem and i am not sure what's the solution. i haven't yet tried https://neotires.com and didn't sorted it out, but Roberts i will try it out and see if it works for me. thanks tracetheory for updating as well. if something goes wrong may i come back here asking some questions? thanks a lot for everything.

[Roberts_Clif]

Hope it Works!!!