Thermistor replacement - Hardware, firmware and software help

RE: Thermistor replacement

thirdstring3 — Wed, 29 Apr 2020 17:42:11 +0000

Do you see the silver tabs on the top of the left connector? (White wires) They are part of the pin terminal. If you push those in, it will release the pin/wire from the connector. There is a tiny chance that the pins are the same on the two, just with different connectors. I highly doubt they match, but if they are just sitting there...

Do note that the tabs are springy, but if you push too hard, they will bend, so you will need to gently pull it back out a little with tweezers or a needle to get the tab back into place where it will lock into the connector.

RE: Thermistor replacement

Mike — Tue, 28 Apr 2020 19:31:38 +0000

Thank you Joan. I will look into getting the wire.

RE: Thermistor replacement

JoanTabb — Tue, 28 Apr 2020 15:22:39 +0000

Flexible Silicone wire is also a good thing to have in stock, 16AWG for the heatbed power, 24AWG for other low power wires.

regards Joan

RE: Thermistor replacement

Mike — Tue, 28 Apr 2020 02:25:50 +0000

OK, I found out a couple of things. It seems the wire itself is 31 AWG (0.22 mm) and it seems really hard to find a crimp or connector for that gage. The connector appears to be a MX3N Molex, which also seems hard to find. So, to get my printer running I'll order the part from Printed Solid as Karl recommened and look at getting a soldering iron, heat shrink, and heat gun as I am able. Thank you for your help and insight.

RE: Thermistor replacement

Mike — Tue, 28 Apr 2020 00:53:53 +0000

Great. Thank you for both of those replies. Soldering and heat shrink it a bit more advanced that I have access to. I'm thinking twisting the leads together might not be adequate, although I think I have some ancient electrical tape somewhere. Would a simple crimp work? I will try this the next time I can get to Home Depot.

Also, is there a way to just get the connector and insert the wires directly? What kind of connector does Prusa use?

New thermistor on left, Prusa on the right.

RE: Thermistor replacement

karl-herbert — Mon, 27 Apr 2020 22:57:59 +0000

Posted by: @sea-dart
A wire on my thermistor broke so I tried to find a replacement. I got one off Amazon but the connector is different and won't fit in the control board of my Mk3. Two questions then:
1. Is there a recommended replacement thermistor I can easily get the the USA?
2. Is there a way I can convert from the connector on the new thermistor to one that fits?
New and old thermistor connectors
(sorry, I can't figure out how to attach the photo itself to this post)

As Joan explained: The cheapest way would be soldering. Polarity is irrelevant to resistance. Resistance should be 100kohms at 25 degrees C.

I you want to buy a new one: https://www.printedsolid.com/products/prusa-mk2-mk3-thermistor-cartridge

RE: Thermistor replacement

JoanTabb — Mon, 27 Apr 2020 20:36:36 +0000

Hi Sea Dart,

with the text input window open, also open file manager, in a reduced size window. then drag your picture file into the text input windos, which should turn blue, when the file is in the correct place ... then drop the file... another window should open like below

I hope that helps...
cut both plugs off, leaving enough cable on the Prusa Plug, to strip the insulation and solder the ends of the prusa plug to the new thermistor wires, insulate (preferably with heat shrink tubing but tape will do. and then install

Thermistors are not polarity conscious...

(was the new thermistor a 100Kohm thermistor? )

regards Joan

Thermistor replacement

Mike — Mon, 27 Apr 2020 19:56:18 +0000

A wire on my thermistor broke so I tried to find a replacement. I got one off Amazon but the connector is different and won't fit in the control board of my Mk3. Two questions then:

1. Is there a recommended replacement thermistor I can easily get the the USA?

2. Is there a way I can convert from the connector on the new thermistor to one that fits?

New and old thermistor connectors

(sorry, I can't figure out how to attach the photo itself to this post)