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

You should use the continuity tester of any multimeter to check the wires before replacing them. You can connect one lead to where the heated bed wire plugs into the motherboard, and the second to where the other end of that wire is on the heated bed. Do that to check all four wires while jiggling them around to check for internal breaks.


If all four wires going to the heated bed are well connected you probably have a bad thermistor. This is that little black thing mounted to the center of the heated bed that measures the temperature of the bed. You can connect an ohmmeter to either side of the little black thing to see if it gives the correct amount of resistance (in the neighborhood of 100k ohms)


I had to replace mine, you just need any 100k ohm glass bead thermistor, it doesnt even have to be the same exact type as the one on the board. I used this one:


https://www.amazon.com/gp/product/B01N4KY6TR


it has leads and a plug that i plugged directly into the motherboard and just taped it to the bottom of the heated bed with kapton tape and works perfectly.

Good luck!

Use this as an opportunity to stock up on a few different spare parts. I recommend always having those tubes, nozzels, heaters, thermistors, and possibly even one set of spare cooling fans. I did one purchase a little over a year ago, was like $40, has saved me from having downtime on several occasions.

I did the same thing while changing a nozzle. I ordered https://www.amazon.ca/gp/aw/d/B01N4KY6TR and it was a perfect replacement for my v2. Pretty easy to replace too, just involves some unscrewing of the casing and running the new wire to plug it in (no soldering required).

I grabbed these for my Ender when I had a similar issue. Always great to have a few extra on hand.

https://www.amazon.com/dp/B01N4KY6TR/ref=cm_sw_r_sms_awdb_t1_Fc0UCb9KK5K1E

Thanks for the input. Is 100K standard for most printers? I couldn't find anything in the manual except a tiny picture of it and I cannot read what it says on the thermistor. I found this one on Amazon but I would prefer not to buy the wrong thing as I'd have no other use for it but my printer.

I had this same issue a couple months ago. My thermistor on the extruder was busted (specifically one of the tiny wires to the very tip was snapped, but still making poor contact). 8 bucks on amazon for a pack of 5, ten minute swap, no issues since.

This is what I bought: https://www.amazon.com/dp/B01N4KY6TR/ref=cm_sw_r_cp_apa_i_Kg9qDbKNPFPMQ

I misread your post and posted a bad reply, deleted.

I agree with /u/LosinCash, it's probably the thermistor. It may not be properly contacting the heater block, pull it and check it's into the hole properly.

Also be careful those wires are brittle and easily broken. Another thing to watch for is that the wires don't contact the heater block.

Here's a link if you need some new ones:

https://smile.amazon.com/gp/product/B01N4KY6TR/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

You don't need a whole hotend unless you planned to upgrade it anyway for running hotter plastics (All metal hotend like the E3D)

EDIT: Oh yeah - the screw that holds the thermistor does NOT screw down on it!! It's GLASS. The washer holds the wires to keep it in the hole.

PuterPro

I recently went through exactly this same situation. I was ready to upgrade to a microswiss all-metal hotend and the catastrophic failure of the print leaving gunk all over my heater block forced the issue. In my case, I opted to replace everything I could including the thermistor and heating element. They are both very inexpensive and you should have a spare laying around anyway in case you need one in a hurry. So...how to clean your heating block...

Fire. Seriously. I used a combination of blowtorch and solvent to remove all the gunk (and mine was a LOT worse than yours...it basically encapsulated one entire end of my heater block, entombing the thermistor, heater and associated wiring).

I used your typical propane torch, holding my heater block in a vise or vise grips. I'd heat it up then quickly wipe away the melted PLA with a clean cloth. Heat, repeat. Then I'd soak the whole thing in some solvent (acetone, MEK, etc). Repeat until clean. Pay careful attention to the tiny setscrew that holds the heater in place...work it free with a hex wrench while it is hot...chances are you got some PLA stuck on there, too. Obviously be super careful when you do this. Ventilation, fire-extinguisher handy, your mom on speed-dial.

When you replace the thermistor and heating element you'll need to do some soldering. This is pretty unavoidable. Those elements come with very long wires attached to them and the Wanhao/MP print heat doesn't need that length. Clip it short, make good solders and use heatshrink over your joints. For the thermistor I simply cut out the center section of the wire and spliced the connector back to the component at the length i needed.

Now, when you put it all back together you will have the option of re-wrapping the heater block with cotton and Kapton tape. People seem split on if this is necessary, but since I'd battled heat creep before I didn't want to introduce any more heat up the block...so I opted to do it. It's a bit tricky if you get the non-punched cotton strips like I did. Luckily I had hole punches handy to make the provision for the hotend and nozzle to get thru the insulation. If you don't have these tools (or don't quite know how to do it), i'd shop around for pre-punched sets.

good luck. Let me know if you need any more help.

here are the parts i used:

https://www.amazon.com/gp/product/B071K8Z9KF/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B01N4KY6TR/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B076NW3GNH/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

https://www.amazon.com/gp/product/B01E1HANLS/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1

Not sure if I was lucky or if it is an old image but these I purchased off Amazon actually had the white connectors already attached which plug directly into Mini's board.

https://www.amazon.com/gp/product/B01N4KY6TR

Just removed the old one entirely and replaced it with one of these. Splicing anywhere along the area that travels up and down as well as left and right is going to wear the spice after time. If you do have to splice or solder any of these wires make sure the point of the splice is somewhere inside the Mini's structure and not with the Bowden tube so there is no constant flex on it.

Here’s the links to the things I bought.
Heater cartridge
SEFUSE
HeatBlocks, Nozzles, Heatbreak
100K Thermistor

I must have on accident, I was fiddling around with the screw because I couldnt get it correctly because the wire didnt want to stay in the hole and must have came out a bit to be pinched by it, and I heard a crack and looked, and all was left was copper on the wires

​

Guess I need new one now, https://www.amazon.ca/Happisland-Thermistor-Wiring-Printer-Heatbed/dp/B01N4KY6TR/ref=sr_1_7?crid=32XZGNIRBJ19S&keywords=100k+thermistor+printer&qid=1558652602&s=gateway&sprefix=100k+ther%2Caps%2C155&sr=8-7


Are these any good/ the same and hopefully not catch my house on fire?