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didier.j
(@didier-j)
New Member
Self Test Error: Heater Thermistor not connected

Hello,

I have mounted a Prusa Mk3 during Christmas break.
During Configuration wizard, i am having a error: Self Test Error: Heater Thermistor not connected
1. I checked cabling,
2. I did mesaure HotEnd thermistor resitance which looks ok and varies with finger's temp.
3. I then run a pre-heat and saw temperature of both hotend and regulation looks to work.

Please advise on next steps to solve this issue.
Best regards,
Didier

Posted : 05/01/2019 10:11 pm
thrawn86
(@thrawn86)
Honorable Member
Re: Self Test Error: Heater Thermistor not connected


Please advise on next steps to solve this issue.
Best regards,
Didier

it could be intermittent. whats happens if you hook up the probe and jiggle it around and move the bed to its extents??

does your bed use the new screw terminals or the old soldered-on thermistor wires?

Posted : 05/01/2019 10:32 pm
didier.j
(@didier-j)
New Member
Topic starter answered:
Re: Self Test Error: Heater Thermistor not connected

Hi curtis.c2

The bed is connected with screews. I checked thermistor resistance from the connector of the board side. I moved also the bed and cable to see if any connectivity issue can be identified.

Nevertheless, the error message appears during the hot end selftest. I checked also thermistor resistance.
I suspect either hotend thermistor is having a pb, or a connectivity issue on the board as looks like booth bed and hot end were tested before shipment.
I also updated the firmware to ensure we have the latest version there.

Any ideas is welcome.
Didier

Posted : 07/01/2019 9:01 am
dale.d3
(@dale-d3)
Eminent Member
Re: Self Test Error: Heater Thermistor not connected

Make sure you have the thermistor pulled into the proper slot. The slots are small, and care must be taken to get the right cable in the right slot. I know this because I made that error. I corrected it in troubleshooting the same message you got.

Posted : 07/01/2019 6:26 pm
Bunny Science
(@bunny-science)
Noble Member
Re: Self Test Error: Heater Thermistor not connected

You have both hot end and heat bed temperatures appearing on the display. Therefore, I conclude you are indeed plugged into the correct EINSY sockets.

This is by definition an intermittent connection failure.

However you are reporting a heat bed thermistor error during HOT END portion of self test. I'm not certain based on that timing whether it is the heat bed thermistor that is having the issue vs the hot end thermistor.

If the heat bed, only two place remain to check for bad connection.
1. The solder joints between cable and thermistor. I don't think this is terribly likely
2. The crimps inside the molex connector. You can carefully free the pins from the molex housing by releasing the tiny metal latches. Inspect for proper crimping of the wires.

If the hot end thermistor, the molex crimps for this are prone to failure if the yellow/green heatshrink is too near the molex connector. I would definitely check the crimps in that molex.

Posted : 07/01/2019 7:49 pm
didier.j
(@didier-j)
New Member
Topic starter answered:
Re: Self Test Error: Heater Thermistor not connected

Hello

Thx for your comments.

I made few test again.
1. On both thermistor (bed and hotend) i check cabling, crimps. Connectivity is correct and I see a resistance of around 200kOhms.
2. When connected to the board, error in self test always appear.
3. I checked all fuses and none where burned.
4. I checked values on the main screen, and both tempearture looks correct.
5. I ran a PLA pre-heat which went well to target value for both bed and hotend.

In conclusion, Error in selt test still here. Does anyone could explain what this code/self test is testing ?
How shall i proceed ? Any idea ? Do it means that I can forget this self test issue and run the 3dprinter as is ?
What's Prusa support proposal to solve such issue ?

Thanks.
Didier

Posted : 14/01/2019 12:02 am
Djamuka
(@djamuka)
Eminent Member
Re: Self Test Error: Heater Thermistor not connected

Hi there, did you find the solution? same trouble here!

EDIT Got the answer by the chat, room temperature is too cold 14° , it must be 16° minimum....for the calibration wizard...

Posted : 22/01/2019 11:33 pm
newdragone
(@newdragone)
New Member
RE: Self Test Error: Heater Thermistor not connected

I'm currently having the same issue. First Time builder over here, i checked all connections, temperatures come over on LCD Screen. During the Self test, i hear a beep, and then a minute or so and then the error message. Any thoughts? Thank you

Posted : 10/04/2020 8:05 pm
karl-herbert
(@karl-herbert)
Illustrious Member
RE: Self Test Error: Heater Thermistor not connected
Posted by: @didier-j

Hello

Thx for your comments.

I made few test again.
1. On both thermistor (bed and hotend) i check cabling, crimps. Connectivity is correct and I see a resistance of around 200kOhms.
2. When connected to the board, error in self test always appear.
3. I checked all fuses and none where burned.
4. I checked values on the main screen, and both tempearture looks correct.
5. I ran a PLA pre-heat which went well to target value for both bed and hotend.

In conclusion, Error in selt test still here. Does anyone could explain what this code/self test is testing ?
How shall i proceed ? Any idea ? Do it means that I can forget this self test issue and run the 3dprinter as is ?
What's Prusa support proposal to solve such issue ?

Thanks.
Didier

Hello, 200kohms is too much, should have about 100kohms (0 degree C.), otherwise you will get falsified temperature values. I would check it again.

Here is a temptable for the nozzle:

Ambient Temp Resistance
23.7 109.23
   
Temp Resistance
0 100.0000
5 101.9536
10 103.9043
15 105.8521
20 107.7971
25 109.7394
30 111.6788
35 113.6154
40 115.5491
45 117.4801
50 119.4081
55 121.3333
60 123.2555
65 125.1748
70 127.0911
75 129.0043
80 130.9144
85 132.8212
90 134.7249
95 136.6251
100 138.5220
105 140.4153
110 142.3051
115 144.1911
120 146.0732
125 147.9515
130 149.8256
135 151.6956
140 153.5612
145 155.4224
150 157.2789
155 159.1307
160 160.9775
165 162.8193
170 164.6557
175 166.4867
180 168.3121
185 170.1317
190 171.9452
195 173.7525
200 175.5534
205 177.3476
210 179.1349
215 180.9151
220 182.6880
225 184.4533
230 186.2108
235 187.9601
240 189.7012
245 191.4336
250 193.1571
255 194.8715
260 196.5764
265 198.2716
270 199.9567
275 201.6315
280 203.2956
285 204.9488
290 206.5907
295 208.2209
300 209.8392
305 211.4452

Statt zu klagen, dass wir nicht alles haben, was wir wollen, sollten wir lieber dankbar sein, dass wir nicht alles bekommen, was wir verdienen.

Posted : 10/04/2020 8:40 pm
pwiltsey liked
Lauren G
(@lauren-g)
New Member
RE: Self Test Error: Heater Thermistor not connected

Check for blown fuses. I tried every trick under the sun and couldn't figure out what the problem was. I finally ran into a prusa forum and saw someone mention to check the fuses and sure enough the one for my heater was blown. Replaced the fuse and now it works like new!

Blown Fuse

Posted : 16/04/2021 12:27 am
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