hot end temperature extreme fluctuation

All of a sudden hot end temperature started fluctuate very badly, but only when printing. If I move the hot end on the table with motors disabled even rapidly no change on temp. When adaptive bed meshing, no change or if I wiggle the wiring nothing change. Fan is at same state (off) when printing also. Any ideas?
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7 Replies
Jäärne
JäärneOP3mo ago
Minor update: I tried to print something small and since it survives the first layers the problem goes away..
TheTik
TheTik3mo ago
The actual temp can't fluctuate that fast, too much thermal inertia. That points to something electrical. Wiggled all the wires from one end to the other?
Jäärne
JäärneOP3mo ago
I think wiggle test is done. Came to same conclusion too and wiggled everything maybe 5 separate times with different hot end temperatures and no fluctuation.. Can it be slicer related? For me atleast the print shows constant temp when sliced.. the fluctutation starts RIGHT when the print starts after prime blob. When layer counter resets the temp goes crazy
TheTik
TheTik3mo ago
How does a pid calibrate go?
Jäärne
JäärneOP3mo ago
Well when target 250 it overshoots by 7*deg but goes only to 244 when cooling to 244. Didnt loose the hysterisis.
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Jäärne
JäärneOP3mo ago
for the 6th time I tried the wiggle test when hot end tried to reach first layer temp and got the temperature to fluctuate. I think you (TheTik) was right. I will tell you when I find the broken wire.. First of all sorry for the amount of messages. Issue solved: The cables of thermistor and especially the connector got pinched when print head did the -X movement from side of the table to start of the print after the prime blob. Moved the connector to the other side of the wiring harness and no issues anymore. Special Thanks for @TheTik .
TheTik
TheTik3mo ago
woohoo!
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