@chrishamm I appreciate the help, it worked fantastic!

So, last night while in the middle of another large print, my Temp2 input started having the same issue. It reads -11c now at ambient temp. I am using a different PT1000 sensor than when it originally happened.

I was thinking, and my only possible explanations I could come up with are;

A. The longer run of cable for the PT1000 is drawing too much current to check for resistance of the thermocouple, and causing a resistor somewhere on the board to burn up (but then it would be open circuit, so idk)

B. A resistor somewhere is being damaged by the inductive current induced from the 100w heater cables ran next to the temp sensor. The new wiring harness has all of the cables bundled tightly together.

Either way I am going to troubleshoot it later today, and in the meantime I am ordering the PT100 daughter board, so that way if the problem keeps happening I don't damage another temperature input. I am hoping I can find a faulty resistor somewhere on the board and just solder a new one on.

Another odd thing that has been happening that I am beginning to suspect may be a related issue is that my BLTouch will deploy while printing. This is what is making me suspect an inductive current being the problem, maybe weird voltage spikes are causing the BLTouch to deploy, and damage the temperature sensors. Either way the issue obviously is caused by my new wiring harness, so I guess I get to take it all apart (yay )

@infiniteloop My bad it was pretty late when I wrote that. Duet 3 HC, the heater is a 350mmx350mm 24v heater that is 430watts.

Hey all! I have had many trouble free years with my duet, other than my dumbass burning out temperature sensor slots on the board. Today I went to start a print, and had a weird glitch where the endstop didn't trigger. Cue the horrible stepper grinding the belt noise, and I shut down the printer and restarted it. Homed nicely. Went to start printing, everything is fine. I notice my bed temp was about 7f above where I set it, and rising. So I shut down the bed on the web control, set it to inactive. Still rising. Cancel the print, and watch it continue to rise. Restarted the machine, and disconnected the hot bed. Put a multi meter to the bed connection, and as soon as I hit the power switch the bed receives 24v. I don't have a SSR or anything since my chamber is heated and my bed usually doesn't pull a ton. Is this something I can diagnose and fix myself further? I don't mind buying another duet, and honestly I'm kind of leaning towards that since I have been hard on this one. I had temp fuses in case something like this happens, but it's like the time my washing machine overflowed and flooded the two condos beneath me... I don't want to leave the same one unattended I'd rather just buy a new one lol. Just hoping it's something that's as simple as resoldering a relay.

Any advice is appreciated!

So, last night while in the middle of another large print, my Temp2 input started having the same issue. It reads -11c now at ambient temp. I am using a different PT1000 sensor than when it originally happened.

I was thinking, and my only possible explanations I could come up with are;

A. The longer run of cable for the PT1000 is drawing too much current to check for resistance of the thermocouple, and causing a resistor somewhere on the board to burn up (but then it would be open circuit, so idk)

B. A resistor somewhere is being damaged by the inductive current induced from the 100w heater cables ran next to the temp sensor. The new wiring harness has all of the cables bundled tightly together.

Either way I am going to troubleshoot it later today, and in the meantime I am ordering the PT100 daughter board, so that way if the problem keeps happening I don't damage another temperature input. I am hoping I can find a faulty resistor somewhere on the board and just solder a new one on.

Another odd thing that has been happening that I am beginning to suspect may be a related issue is that my BLTouch will deploy while printing. This is what is making me suspect an inductive current being the problem, maybe weird voltage spikes are causing the BLTouch to deploy, and damage the temperature sensors. Either way the issue obviously is caused by my new wiring harness, so I guess I get to take it all apart (yay )

@phaedrux

Hello! I tried the semi auto calibration just now since I don't have resistors in all of those resistances. Same thing, it shows close to zero c. I shorted it on the second time, the first time it had an open circuit when I ran the command. I am in the process of switching it to temp2, so I can get it printing again. I am probably going to switch to PT100's in the future, so its not a big deal.

And your right, I have the two fans switched and just never got around to fixing its since I almost never use the part cooling fan haha. Now that I'm in there, I might as well fix it now, thanks!

EDIT: Switched thermistor to temp2, its working now. Now I wish I hadn't cut it off from the heater block so fast, lol. Soldering the type of wire the connection is made out of is a PITA.

I have had many many hours of error free printing with my duet 3 6hc. Recently I installed a cable track and some new rails onto my printer, so I had to lengthen the wires by about twice as long as they were before. Everything ran good, but then yesterday mid print I had a heater fault. At first I couldn't figure out why it had a heater fault, until it cooled down and the temperature of the nozzle was at zero degrees celcius, or around there. My ambient temperature was 28c, and so I just assumed I had a faulty probe. I cut it off and checked it with a multimeter, and the resistance was correct. Confused, I hooked up a brand new PT1000 probe I had laying around, and it still read the same at or around zero Celsius. It rises and falls when I touch it and cool it, just seems to be rising at a different rate. I put it in freezing water and it read well below zero celcius. I took the wiring harness out of the equation by connecting it directly to the Duet, with a pair of alligator clips, and it still read the same thing. This happened mid print, and I didn't change anything in the system files for a few months. Has anybody experience this? I will try using the Temp2 input tomorrow, and see if that reads correctly. The hotbed is still reading correctly, and it uses a PT1000 sensor as well. I looked at the PT1000 temp chart, and the resistances of both of them were close to 1087 ohms, which is correct for my ambient temp.

Is it possible that it could be a board issue? I switched out the proven functioning bed sensor with the tool1 sensor, and it shows the same wrong temperature of around 0c.

system config is attached. config-override is :

; config-override.g file generated in response to M500 at 2021-07-03 14:36
; This is a system-generated file - do not edit
; Heater model parameters
M307 H0 R2.766 C157.320:157.320 D5.64 S1.00 V23.9 B0
M307 H1 R0.169 C725.964:725.964 D10.24 S1.00 V24.0 B0
; Workplace coordinates
G10 L2 P1 X0.00 Y0.00 Z0.00
G10 L2 P2 X0.00 Y0.00 Z0.00
G10 L2 P3 X0.00 Y0.00 Z0.00
G10 L2 P4 X0.00 Y0.00 Z0.00
G10 L2 P5 X0.00 Y0.00 Z0.00
G10 L2 P6 X0.00 Y0.00 Z0.00
G10 L2 P7 X0.00 Y0.00 Z0.00
G10 L2 P8 X0.00 Y0.00 Z0.00
G10 L2 P9 X0.00 Y0.00 Z0.00
M486 S-1

Config attachment:
config.g

Edit: This is the console during the failure. So glad it stopped it, since I was shopping at the time and I am sure the nozzle was way hotter than it was supposed to be since it is showing under temp.

@chrishamm I appreciate the help, it worked fantastic!

Hello!

I printed off a vent that takes hot air from the top of my chamber and sucks it to the bottom. I have two temp sensors, one at the top of the chamber, and one at the bottom. Is there a way to compare these two values and turn on the blower only when they vary by x amount?

On a related matter, for redundant temperature sensors like they have on the mosquito magnum, how would that be set up in the firmware? Where if one fails, it pauses the print with the option to continue.