Thermistor cable management  

Thermistor cable management

i have recently had issues with my hotend thermistor on my MK3s printer. I bought a Kit in March and assembled it. Everything worked fine for a bit over a month but then an accident happened where my whole print lifted off of the plate and parts of it wrapped around the nozzle. This caused the fan shroud and the support for the print fan to break. After this, I was able to hold the print fan in place with a piece of yarn and print replacement parts as well as a few other things I needed until I would get a chance to replace the broken parts. Everything worked great until one night, partly through a print job, the printer halted and there was a “mintemp error”.  Upon investigation and after chatting with Prusa support online, I had found that there was some very minor damage to the thermistor cable.

So, I then ordered and paid for a new thermistor and tried to install it. Upon trying this and after removing most of the caked on filament from the bottom part of the hotend, I discovered that the set screws were either stripped or firmly welded in place. So, after again chatting with Prusa, I bought and paid for a whole brand new hotend assembly which I just received day before yesterday.  That evening, I proceeded to install the new hotend and recalibrate the printer. Other than having to overcome a couple of minor hiccups, everything went perfectly. The printer was working again and after a few tries, I was able to begin printing a bigger print that I was wanting to do. A few hours after I started my latest attempt to print the project last night, I went to check on the printer only to find that I again got a mintemp error!

i haven’t had time yet to investigate every possible cause of what could have happened but I again noticed some very minor cable damage. The copper is exposed on a very small part of the wire but doesn’t appear to be broken. I did take an extra step to try and secure the wires and prevent any of them from touching or rubbing on anything by putting in an extra zip tie close to the hotend, but it appears that I didn’t do quite enough. The cables maybe could have been pulled a bit tighter during the hotend replacement but I don’t know of anything else that I could have done wrong.

i am going to again replace the thermistor (removing the existing one from the hotend shouldn’t be an issue this time), or try and solder and tape the existing one first to see if that resolved the issue.

What are the best ways to safeguard the wires so that they can’t touch or rub on anything during printer operation? A good friend of mine suggested that the motherboard could be producing false error readings or that it may be an issue with the latest firmware. Anyone else have this issue? My friend suggested reflashing the board and possibly trying older firmware to resolve the issue. I have just recently bought my printer and have already spent about $200 for new parts. A new board would cost me about $250 (I live in Canada so exchange rates, import duties and taxes plus shipping costs makes things more expensive).