Thermistor issues i think

I got the printer, set up and printed for 3 days almost non stop with no issues. Then mid print the bed leveling wheels came off and I ended with a medium to large size of filament stuck to the hot end. I was not able to use the hot end to heat up the filament to take it off so I used a heat gun on low heat. When taking the hot end apart to inspect it I noticed the thermistor bulb was broken so I replaced it and now at room temp it says 90 C instead of whatever the room is at but it will now heat up to 240 i havent tried higher as thats the temp i use for petg. However now the bed says 0 so I was guessing the thermistor was gone in that as well so I tried replacing it on the bed as well with no luck. I am not sure what to do next the screen says to connect to a serial monitor but I a not sure how to do so and even if I do what to do after that. Did I not use the right thermistor maybe? Does the bed and hot end use different thermistor?
Any help appreciated thanks.

I am suspecting that you have the incorrect thermistor installed.

There are different variations of them standard Creality is an NTC100K

If you have a Ohm meter and you check across both terminals you should be measuring something in the range of 100K** 100 KΩ @ 25 °C -55 to 150 °C, Bear in mind if your room temp is 21 deg your resistance will be different, +/- 2%

Interesting article if you want some further information

If you put in a different one it will show the wrong reading.


1 Like

So I take it you have two problems: the temperature readings on the hot-end are no longer valid and the bed has stopped reporting temperature readings?

With respect to the hot end, the thermistor you bought is likely not the same model as came with the printer. It’s a Negative Temperature Coefficient, 100K thermistor which is mostly OK.
(Translation for the uninitiated: It reads 100KΩ (100,000 ohms) at 25°C and the resistance decreases as the temperature rises)

What is likely wrong is the Coefficient value. Different models of 100KΩ NTC thermistors will vary their resistance by different amounts for a given change in temperature. They will all read 100KΩ at 25°C and they will all decrease their resistance with increases in temperature, but how much they change will depend on the model. Fortunately, the Thermistor vendor gave you your answer: “For 3D printers: use TEMP_SENSOR 11 in Marlin Firmware”

Since there are dozens of different models of Thermistors, the software that runs your printer can be configured to use a variety of them by changing a value in (I think) your configuration.h file.

At this point, I’m going to leave you in the capable hands of someone else as I have never compiled and installed 3D printer firmware and I don’t feel comfortable giving advise on the subject. I know it’s technically very simple: the configuration.h file is simply a text file. You literally alter one line of text and re-compile the firmware, put it on an SD card and insert it into the printer, then reboot.

Alternatively, check the printer’s manual and order the correct model of thermistor. Frankly, this is the route I’d go. If you install a thermistor that is not “standard” for your printer model (what model is it, anyway?), then every time there is a firmware update, you’re going to have to remember to make the above edit since firmware updates will always assume the use of “standard” equipment. On the other hand, thermistors are cheap and staying consistent will save you hassles down the road.

As for the bed problem, some models of printer, like my Ender 5Pro, have the bed wires (heater and thermistor) simply soldered to the underside of the bed. Without supports, it’s prone to breakage. You may simply need to re-solder it. It all depends on what model printer you have.

1 Like

Awesome thanks for the info I will definatly read that article when I get a few min.

Thanks thats lots of good info, I have compiled using vs code before for my ender 3 pro, its not too hard even for a newb like me as long as you have good instructions somewhere telling you what to change.
Sorry my current printer im talking about is a cr10s pro v2. I changed the bed thermistor a couple of times and all said 0 upon stary up and error ever time I tried to heat the bed. However I used the same one I used for my hot end for the bed so maybe its wring for both. None of the stores I usually order from have any in stock and thats actually why I ordered it from Amazon in the first place. I will definatly be ordering the proper thermistor for it as soon as I’m able too I don’t want to have to remember to change it ever update I do in the future

Does creality use the same thermistor for all their printers? I thought they did but I’m seeing different ones but is that just different legnths?

On Creality Machines.

NTC 3950 24V machines = Bed
NTC 3950 12V machines = Both Nozzle and Bed
NTC 100K = Nozzle

According to this I have the right thermistor in both the hot end and bed. And still all the same.

I’m really not sure where to go now

Cr10 Pro series and MAX uss the Same Thermistor , different lengths though

For Nozzle on CR-10S Pro:

For NOzzle on CR-10 MAX:

I put this one in, from what I read above I thought it was right and when I called 3d printingcanada they agreed that it was.

I also put this one on the bed:

1 Like

Took them a month to come to the conclusion but creàlity is sending me a new board and is calling it a board failure issue and are covering it under warranty.

1 Like