Printer stops working because extruder's temperature control is screwed up...

ToTo

Hi all,

I've got the JGAurora A5 (I think it's the newer version - S) couple months ago and are still playing around with settings to get better printouts.  So far I've learned more and more about the machine - its parts and what's their functions, mainly via articles and tips/tricks on the internet.  It's been working good (I think), until now.  I did (probably) a (stupid) thing on it, and now it's not working.  I tried to replace the heater block and accidentally separated the two thermometer wires.  I tried to twist them together but that didn't work very well.  So I had an (probably stupid) idea of soldering them (since I thought lead has melting point of ~ 327°C, so it wouldn't melt during normal PLA printing, which is ~ 195°C).  But I guess the soldering temperature (probably around 400 - 500°C?) probably did some damage to the temperature sensor through the thermometer wires.  After I put everything back together, now when I turn the machine on, everything seems to be normal (i.e. homing, moving up/down, etc.) until I change/raise the extruder's temperature.  The display of the extruder's temperatre now shows "357/180" (I guess 357°C was the temperature that the sensor experienced during the soldering, which is around the melting point for lead).  And as soon as I started changing the temperature, everything else stopped working (i.e. none of the control buttons on the display works). Btw, I unplugged the printer while I did the soldering.

Does anyone have any suggestions to fix this? Maybe if there's some way to reset the machine (to get it out the 'shocked" state?)...

Thanks in advance for your help.

TomD

Samuel Pinches

Hi @ToTo , unfortunately 357C means that there is a short circuit on the thermistor line. You will need to replace the thermistor. The machine freezing up is part of the safety system that disables the machine when it detects any error with the heating systems. Turning the printer off and on will reenable it, but because the temperature is stuck high it will freeze up again.

ToTo

Thanks, Samuel, for your quick response.  Where's the thermister located? If I follow the (black) thermocouple wires would it lead me to the thermister? And what type do I need to buy? (a link would be nice).  Thanks again.

ToTo

I saw a Youtube clip by DaHai8 showing to replace the thermister's tip, and he showed to push the tip all the way in - along with part of the insulating tubes.  I didn't push mine all the way in, and the insulating tubes are NOT inside the hole as DaHai8 did.  So maybe that's cause of the short circuit, I guess?  I'll try to fix that when I get home and see if that'd fix the problem...

ToTo

I found this thermister on Amazon:

https://smile.amazon.com/Mmei-Thermistor-Printer-Extruder-pre-wired/dp/B01HCKI7NW/ref=sr_1_18?ie=UTF8&qid=1549383742&sr=8-18&keywords=thermister+3d+printer

Is this the correct one for JGAurora A5?  It looks like their tips is more than just being soldered together...  So what I did (soldering with lead) was totally wrong, think.

Samuel Pinches

Yes, a thermstor is different to a thermocouple.
Those will probably work, but I have listed original replacements on the wiki here:
https://jgaurorawiki.com/essentials#spare-parts

Unfortunately none of them are shipping from the USA

ToTo

Thanks very much, Samuel!  This is a very helpful source for spare/upgraded parts and supplies.  Thanks again for your help and time.