Suggestions for order of thermistor troubleshooting?

[smiley]

So i had the dreaded "extruder 0: temp sensor defect Error :Printer set into dry run mode until restart!" message. And the bummer is, it came about 40% through a part that was printing just peachy until then.

After reading the forums, the causes seem limited to (1) busted thermistor - if I'm lucky just a wiring defect, or (2) busted RAMBO.

AFAICT the approved way to troubleshoot this is:

switch the bed thermistor leads with the hotend thermistor leads on the RAMBO and see if that changes which temp sensor defect error is reported. that is, (i) if it stays on extruder 0, my RAMBO has a bad circuit on those pins and I need to switch pins to keep using the board, or (ii) if after the switch extruder 1 is suddenly giving me the temp sensor defect error, it's the thermistor (or wiring) that is bad and the RAMBO is ok.

Assuming it's option (ii) and I need to fix the thermistor, from what I can tell the approved method is to take the hotend apart and check for obvious breaks. Right? or is there another approach?

thanks in advance for the help...

(yes, I know, this will eventually end with me just ordering an E3D hotend and a mount from trickLaser but I can't afford to do that this week)

[JohnStack]

So i had the dreaded "extruder 0: temp sensor defect Error :Printer set into dry run mode until restart!" message. And the bummer is, it came about 40% through a part that was printing just peachy until then.

After reading the forums, the causes seem limited to (1) busted thermistor - if I'm lucky just a wiring defect, or (2) busted RAMBO.

AFAICT the approved way to troubleshoot this is:

switch the bed thermistor leads with the hotend thermistor leads on the RAMBO and see if that changes which temp sensor defect error is reported. that is, (i) if it stays on extruder 0, my RAMBO has a bad circuit on those pins and I need to switch pins to keep using the board, or (ii) if after the switch extruder 1 is suddenly giving me the temp sensor defect error, it's the thermistor (or wiring) that is bad and the RAMBO is ok.

Assuming it's option (ii) and I need to fix the thermistor, from what I can tell the approved method is to take the hotend apart and check for obvious breaks. Right? or is there another approach?

thanks in advance for the help...

(yes, I know, this will eventually end with me just ordering an E3D hotend and a mount from trickLaser but I can't afford to do that this week)

Don't switch leads. Unless they've changed the firmware, the E0 error will indicate either one, not one or the other. It's likely your wiring.

1. Turn off power.
2. Disconnect your thermistor from the Rambo
3. Get a multimeter and check the resistance between the thermistor leads. Should be between 98 / 118 *depending on your ambient temp.
4. Check for continuity between each lead and the hot end itself. There should be none. This indicates a short.

If you can resolve before replacing, great.
If you can wiggle any of the wires and not get resistence or conversely, you get a short, it's probably wiring anyway.

Don't switch stuff.

[smiley]

OK, thanks. I have a multimeter right there anyway, i'll do that first and see what comes out.