Reddit reviews Anycubic NTC 3950 100K Thermistor with 1 Meter Wiring and Female Pin Head for RepRap 3D Printer Heatbed or Hot End Pack of 5PCS

I just did the same thing while making a different upgrade. I'm trying Muffler Sealer to put it back in (hasn't arrived yet).

Edit: also replacing my thermistor with this one.

If this isn't a problem from you previously modifying anything related to the thermistor, i would just replace them. Mine was reading 999 and I bought a few off amazon for about $8 iirc and it fixed the problem.
https://www.amazon.com/dp/B01B41K7OM/ref=cm_sw_r_cp_apa_Wn7WBb1NMNEWR

Hey I got you... Trust me I've fucked up more hotends than you'll ever think possible... Thermisistor is the wire on your left and it may be broke but seems to be intact. Now your thermocouple/heater cartridge is not intact(its the cylinder with 2 wires sticking out of it. Still inside ths heater block)

Here are a few things you can do to remedy the situation.

• take the block completely apart, it may require heating to break up the pla. You will need to take the nozzle off and the throat out.
  
  
• once apart continue to heat and remove all excess pla inside the heater block. I use a wire brush since its non abrasive and won't remove any base metal. After all the pla is removed reassemble while its heated. This will prevent further leaks.
  
  
• now for your themisistor turn your printer on and go to where you can see the temp readings if your hot end is reading between 23 to 26 degrees its still good.(+/- 4 degrees tolerance not sure what the ambient temperature of the room is). If the temp is 0 or 290 its broke and you will need a [replacement] (https://www.amazon.com/dp/B01B41K7OM/ref=cm_sw_r_cp_apap_r4GMAiW5oJato) however, you will need to reuse the same board connector.
  
  
• if you have access to a soldering iron you can solder the thermocouple back to the wiring it pulled out of. Once its soldered start a preheat cycle. If it heats up your good. If it doesn't here is a replacement.
  
  Here is a link to my hot end troubles it might be useful.
  
  FYI I'm a firm believer in be able to fix everything yourself. I believe that this philosophy is very applicable in 3d printing. Otherwise you'll just be throwing money at problems witjout every getting to the source of the problem. Hope this helps. Let me know if you have more questions.
  
  

Go ahead and buy some spare thermistors. I hear they go bad pretty quickly. I bought them in bulk :)

https://www.amazon.com/gp/product/B01B41K7OM/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

I used this one:
https://www.amazon.com/gp/product/B01B41K7OM
It wasn't the exact same connector, but it fits fine. Same thermistor, no need to change settings.

I could be wrong, but I believe you are talking about the heatbed thermistor. What makes you think you have a short in it?

The tape is holding it against the bottom surface of the bed. It's not attached in any other way. You can buy 5 for $9. Not sure if you will need to change the firmware configuration for these thermistors.

Thanks for the suggestions! The Maxiwatt hot end looks impressive! I may have to try it out sometime. I just have a couple more questions:

• Is there anything I can do or buy that will help me from breaking the thermistor as I'm installing it?
  
  
• I found a pack online, but I don't know if they're the same as the stock. Stock thermistor and thermistor multipack. Are they the same? If not, how would I adjust the firmware to make it work?

Something like this is all you should need. The problems arise when switching to the cartridge style thermistors that come with E3D hotends. They're supposed to be more durable and accurate, but require tweaking the firmware. The ones I linked to should just plug right in without any extra changes.

Get this pack of Thirmistors now. having that break on me really sucked and it seems to be a problem for others also. I would say the next big thing I did was a new knob. A world of difference.

I personally love this little printer. I don't do much to it but it's there when I need to print parts to fix the other ones.

Yes That is the one I got.

https://www.amazon.com/Anycubic-Thermistor-Wiring-Printer-Heatbed/dp/B01B41K7OM

The old thermistor broke. I used alleged drop in replacements that I found on mpselectmini.com. These are the ones I used. https://www.amazon.com/dp/B01B41K7OM/ref=cm_sw_su_dp I should note that the thermal runaway occurs without even setting a temperature, it just starts heating and that's that. Someone on FB said it could be a bad driver, but I am not sure how I would go about testing that with a meter or scope

H and L makes sense, it would seem it uses normally-closed switches instead of normally-open ones, but it's the same basic principle. H stands for High signal, L for Low. As far as your endstop is concerned, if you want to try plugging them in backwards, you can, but I don't think that'll change anything, as your models seem to be bare switches, so there's no polarity. You could try using a multimeter to test continuity of the switches though. It's also possible that the RAMPS board itself isn't registering it correctly. If you want to test that, you could always pick up another RAMPS online, plug the wires and drivers in exactly the way they're currently plugged into your printer, then swap it with the old RAMPS board on the Arduino. The RAMPS itself just routes power and signals, and has no firmware of its own. This means your firmware won't notice if you've changed the shield on top of it to one with the same layout. I've linked the specific model of RAMPS I use on my prototype printer, which has minor improvements that don't change how it interfaces with the board (specifically, the fuses are a bit bigger, which helps with some problems surrounding running the heatbed and higher powered steppers). You can also change the stepper drivers to these, or another daughterboard that uses the A4988, without any changes to the firmware. It's quite possible the driver boards fried at some point, either with a trim pot adjustment shorting them out, something to do with that second potentiometer changing a setting (from what I can tell that was used to manually set something that's since become completely automatic on these driver boards), or some other issue, as they can be a bit fragile. Luckily, they're cheap, haha.

In response to your earlier question about putting an SD card in, if you want to, go for it. It won't hurt anything. It'll get rid of that error message, for sure. I don't think it'll do anything else of importance, but there may be some quirk of that specific SD card board I don't know about, so there's a possibility it'll be more compliant with one in there.

Oh, okay, I just thought of something. When you're running the machine, is the bed hot while it's turned on? the M105 command you see the machine continuously running is it probing the bed and hotend to see what their temperature is. It says B: 120, which means it thinks the bed is heated to 120C. If the bed isn't heated at all, it may be reporting a fault, which could make the machine not respond to your commands. If you want to test this, next time you turn off the board, unplug the bed's thermistor from it, and turn it on. See what the B value returned after M105 is then. If it's still either reporting 120, or some other crazy number, you may need to replace it with something like this. That may not be exactly the right thermistor, and may report weird temperatures like 60 or 10C at room temperature, due to the tables being slightly mismatched, but it should work well enough for testing, and later on, if the firmware gets changed, it'll be a known variable, so that's not an issue.

I know I've linked a few things to buy, so you may be thinking "bah, I don't want to sink money into this thing if it's this old anyway," but it's worth mentioning I'm only going to link modern components. If there ends up being a point where you just want to throw your hands up and give up working on this i2, every one of the parts I'm linking you is something used by some of the most recent printers around while still being compatible with your current device, so you're not just throwing cash away on legacy tech. Also, in the event that this thing just won't work as it's currently built, I'll happily print out and send you the components necessary to build a totally new one that reuses as many parts as possible from your current i2. Pretty much all I do is design printers, make prints for other people, and give support/advice when it comes to working with them, so I've accrued tons of spare parts that're compatible with a wide variety of things, and you'd not be the first person that's received a box of most of the components necessary to rescue a semi-functional printer out of my spare parts bin and printed out using the end of a few spools I can't use for anything major.

If you bought one of thos $10 clones I think it would be better just buying the cables to your regular direct drive extruder that came with the printer, I bought one these thermistors and I also bought this heater cartridge. There is also this one that comes with 5 thermistors and 5 12v heater cartridges for $12.

It's possible that you forgot to switch the jumper back from USB to VREG. That would explain why the printer is only turning on the lcd and thermistor when plugin in the usb cable.

How about 5 for $9?. Or 10 for $10. You may have to change your firmware to use a NTC 3950 100K thermistor (very common).