Thermistor replacement / nozzle heating  

RE: Thermistor replacement / nozzle heating

Plug the new thermistor into the board, place the thermistor on top the heater block, between the heat sink and heater block, wedge it to contact the heater block using a high temp something, like a small silicon spatula, make sure the wires don't touch anything, and then turn on the heater and keep torque on the set screw until it gets hot enough to break loose. 

I've not had to do this yet, but that's my plan if and when.

RE: Thermistor replacement / nozzle heating

Posted by: @mattbassett

Hey all,

I'm trying to replace my nozzle thermistor after getting a MINTEMP error. I've watched a couple tutorials, bought a replacement thermistor, and have slowly begun the process.  

However, all of the guides say I must pre-heat the hot end to 250C or so, or else the grub screw won't release the thermistor. I can confirm this is true, because I tried to unscrew it cold and that DID NOT work. Unfortunately, my MINTEMP error is preventing me from heating up the nozzle in the first place; it shuts off at the main screen and I can't get the MK3S to respond.  

Catch-22; I can't fix the broken thermistor without heating up the hot end, but I can't heat up the hot end without a working thermistor.

Any advice?

Alternatively you could heat the hotend carefully with a hot air gun. If there is no other way, you have to remove the hotend and possibly drill out the screw (I had to do this with the Mini).

RE: Thermistor replacement / nozzle heating

There might be an even easier way to deal with this: a bit more expensive, but known to work well:

Buy a new heater block. Reuse the heater, nozzle, heat break.

Or buy a new hot end, keep what you don't need as spares:

https://www.amazon.com/E3D-Prusa-MK3-MK3S-HotEnd/dp/B07YNHS6F4

RE: Thermistor replacement / nozzle heating

@tim-m30

So I gave this a shot; plugged in the new thermistor, crammed the new probe up against the heat block, and set it to 250C, hoping. After a few seconds, I got the same error message- MINTEMP, so I'm back to square one. Heat block won't heat, obviously, and all the instructions I've seen for removing the hot end/block start with....heat up your hot end!

😫

RE: Thermistor replacement / nozzle heating

I see three options.  

1. Buy a replacement heat block, thermistor, and heater.  That will set you back about $50.
2. Buy a heat gun.  It will cost about $15-45 you will have many other uses over the life of your printer.  
3. Buy a new hotend.    It will set you back $60-80.