Extruder temperature 763°C

Dear all,

I have encountered a problem with the shown extuder heat by repetier. It says that the extruder is at 763°C while the printer is not working (room temperature). It says this when connected and disconnected.

I think it started when the extruder head accidently rammed a print that was on the bed. I believe it has hit itself with the screw of the 2 white wires at the side of the NTC thermometer. I don’t see any damage or modifications though.

I tried to disconnect, press the reset button on the controllerboard, reconnect, resetting again. I also restarted the computer, took the printer adapter out of the power outlet and took out the USB cable.

After resetting repetier shows in its log:
[color=#0080FF][size=85]19:16:06.825 : FIRMWARE_NAME:Marlin V1; Sprinter/grbl mashup FIRMWARE_URL:http://www.K8200.eu - velleman.eu PROTOCOL_VERSION:1.0 MACHINE_TYPE:K8200 - 3D PRINTER EXTRUDER_COUNT:1
19:16:52.760 : start
19:16:52.760 : echo: External Reset
19:16:52.760 : Marlin 1.0.0
19:16:52.760 : echo: Last Updated: 2013-03-08 | Author: VELLEMAN - GELOEN
19:16:52.760 : echo: Free Memory: 5530 PlannerBufferBytes: 1232
19:16:52.760 : echo:Using Default settings:
19:16:53.028 : Error:0
19:16:53.028 : : Extruder switched off. MAXTEMP triggered !
19:16:53.029 : Error:Printer stopped due to errors. Fix the error and use M999 to restart!. (Temperature is reset. Set it before restarting)
19:24:34.637 : Error:checksum mismatch, Last Line:422
19:24:34.637 : Resend:423[/size][/color]

What could be the cause of this problem? Thank you for your time.


check if the wiring of the thermistor has short-circuit (0 Ohm) …

Regards Bernd


check if the wiring of the thermistor has short-circuit (0 Ohm) …

Regards Bernd[/quote]

What is the best way to measure this? The printer is already fully wired and the female wire connector on the controller board has too narrow openings.

Do I have to cut the wires to measure this?


Apparently, some filament shards (from the print it had hit) crawled under the screw of the NTC thermistor. After pulling them out, resetting and connecting, the temperature was about 23°C.

Repetier shows that extruder heats up and cools down when I manually control it.

Thank you for your reactions.

I also have this issue. I bought a replacement NTC Extruder Thermister and I just finished wiring it up and connected it all up and plugged in the printer to the mains and my laptop, I opened repetier and connected to the printer via the cable provided.

I looked at the extruder temp and it was about 27C and I thought I should touch the NTC to make sure it could read a temp difference which it did.

Then I carried on testing on the instructions.

It told me to heat the extruder and it should stop at 190C which is awesome… So I looked at the temp gauge at the bottom of the screen and it was going up. then I went to do something else for about 20-30 secs and I looked back and it jumped from what it was to 763C… and I thought thats not right so I don’t know what to do.

I am getting so close to printing… So bloody close… :smiley:

I hope someone can help me with this.


Sorry I have worked out what the problem was and it was shorting it self on the extruder

Yes I have the answer to your question.

It had the same stupid problem, but literally all you need to do is just have some electrical tape, or regular tape. The problem that you are having is that the black and white wire that is connected to the thermistor is not stable. All you have to do is just pull up on the two wire till they say the right temp. Then, lean the wires over the big aluminum profile and tape it down. Now your wire are stable, and it mess up anymore.

Had exactly the same problem. My son wired everything up and found it easy until this error of 763 degrees happened.
I checked the wiring and found that he wired the thermistor to the heater wires and visa versa.
After we checked the wires and changed them, all is now well.

Same problem here,

Anybody with a solution?