PT100 connection bad, Molex is the problem, help me analyze
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I have a printer, running great for a few years, it uses a PT100 sensor on the nozzle. It's the E3D brand purchased from Filastruder, so it's the one that comes with Molex Micro-Fit connectors. I use the included pigtail so to avoid doing my own crimps.
A long time ago, I had problems when the print would halt due to a sudden spike in temperature. That was identified as a problem with a bad crimp with the included pigtail. It was easy to fix, I cut it off and used soldering to splice in a new one. And things were fine for another year or so.
This week, turning on the printer, the nozzle seemed to show temperatures about 20 deg C higher than ambient. Wiggling the Molex connector seems to make the temperature drop back to room/ambient.
Everything is zip-tied down neatly with no flex during motion
Questions:
Are the Molex Micro-Fit just that unreliable? Or, does it have some sort of lifespan and I am exceeding its expected lifespan?
A 20 degree C offset, what does that translate into in terms of additional contact resistance (in ohms)? I am having trouble finding specifications raw enough for me to calculate this.
Thanks!
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@frank26080115 the connector is usually reliable, but the crimps can be poor or the wire can fracture inside the insulation next to the crimp if the motion of the tool causes the wire to flex one way and then the other repeatedly.
For a PT100, an increase in reading of 20C corresponds to about 8 ohms resistance at room temperature.
