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Replacement E3D Hotend Thermistor  

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Themaninthesuitcase
(@themaninthesuitcase)
Active Member
Replacement E3D Hotend Thermistor

After my hotend/nozzle came loose I'm needing to clean up the mess.

For the hotend thermistor I already have a spare from E3D but it came with a Molex connector about 10cm down the wires.  Is it possible to fit this as is to a mk2.5S or will I need to remove the connector and solder as per the Prusa spare part

Thanks

Posted : 10/10/2021 6:03 pm
cwbullet
(@cwbullet)
Member
Hmm

My memory is poor but I do not remember soldering thermistors to install one on the Mk2.5S.  I upgraded the one I purchased but I am pretty sure I never soldered anything.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 10/10/2021 11:24 pm
Chicago Keri
(@chicago-keri)
Estimable Member
RE: Thermistor wiring for hotend

Yes, if you use an E3D thermistor you will either need the E3D wire with the Molex connector or you will need to clip off the connector and splice it to the exiting Prusa wiring.

Some tips:

Prusa and E3D thermistors are apparently electrically similar. I use an E3D thermistor with blue wires and a Molex without issue.

Beware of 3rd-party thermistors as many of them have a different response to temperature even though they might both be considered 100k thermistors.  I found this out the hard way by using an E3D thermistor on a Wanhao.... it seems OK at room temp but running temp was way off.

If you elect to splice your wiring, I advise using tiny crimp connectors instead of soldering, as it is mechanically stronger and has less electrical resistance.  Thermistors are not polarized, so wires can be connected either way.  If you do solder, get a good mechanical connection between the wires by twisting together before soldering.

 

Good luck!

 

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Posted : 10/10/2021 11:47 pm
cwbullet
(@cwbullet)
Member
Molex

Molex connectors are crimped and not soldered.  

--------------------
Chuck H
3D Printer Review Blog

Posted : 11/10/2021 12:01 am
Themaninthesuitcase
(@themaninthesuitcase)
Active Member
Topic starter answered:
RE: Thermistor wiring for hotend
Posted by: @cwbullet

My memory is poor but I do not remember soldering thermistors to install one on the Mk2.5S.  I upgraded the one I purchased but I am pretty sure I never soldered anything.  

The one as supplied by Prusa is soldered/crimped, I can't tell as it's under heat shrink. E3D supply these to Prusa and they are available from both Prusa and E3D.

However I ordered a whole hotend assembly from E3D last year as it was cheaper due to shipping.  With this I got the "standard" E3D sensor which comes with a molex connector, so I just reused the original Mk2 sensor as I just wanted to get running.

Posted by: @chicago-keri

Yes, if you use an E3D thermistor you will either need the E3D wire with the Molex connector or you will need to clip off the connector and splice it to the exiting Prusa wiring.

Some tips:

Prusa and E3D thermistors are apparently electrically similar. I use an E3D thermistor with blue wires and a Molex without issue.

Beware of 3rd-party thermistors as many of them have a different response to temperature even though they might both be considered 100k thermistors.  I found this out the hard way by using an E3D thermistor on a Wanhao.... it seems OK at room temp but running temp was way off.

If you elect to splice your wiring, I advise using tiny crimp connectors instead of soldering, as it is mechanically stronger and has less electrical resistance.  Thermistors are not polarized, so wires can be connected either way.  If you do solder, get a good mechanical connection between the wires by twisting together before soldering.

 

Good luck!

 

Thanks I'll see if I can find some crimps in my boxes of bits, I can probably remove the plastic from some ferrules like used on the screw terminals.

Posted : 11/10/2021 7:50 am
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