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Jumpy Hot End Temperature

Posted: Sun Aug 23, 2015 7:03 pm
by toddtman
Hey All,

I recently noticed that the temperature on my hot end will jump around a lot. It happens while printing,heating, and cooling. Sometimes the temperature graph is smooth but other times it will jump up or down by up to 25 degrees. I checked all of the connections and they seem to be secure. Any ideas? Attached is a screen clipping of the simplify 3d graph.

Thanks in advance.

Re: Jumpy Hot End Temperature

Posted: Sun Aug 23, 2015 7:16 pm
by ednisley
toddtman wrote:they seem to be secure
There's a wire in the process of breaking, most likely at the thermistor itself, that's presenting an intermittent high resistance = low temperature to the circuitry in the RAMBo.

The solution, after trying all the other things, will be to replace the thermistor.

More info in this recent thread:
viewtopic.php?f=7&t=2630

Re: Jumpy Hot End Temperature

Posted: Sun Aug 23, 2015 9:20 pm
by toddtman
I broke out the old dmm and testing the resistance of the thermistor again but this time wiggled the wire. With that, the resistance value skyrocketed. I will just have to order a replacement. Thanks for your help @ednisley

Re: Jumpy Hot End Temperature

Posted: Sun Aug 23, 2015 9:30 pm
by ednisley
toddtman wrote:but this time wiggled the wire.
Once you know where to look, it's easy to find! [grin]

We really need a sticky note explaining what to do when the temperature readouts get twitchy, because it happens a lot...