New and odd error.
Rambo controller
Custom Cartesian printer
Bowden Chimera configuration
Marlin 1.1.8
Windows 10 Home
360W 12V supply

This printer has been in use since 2017, I can change head configurations in about 5 minutes and do so fairly often. I have had a volcano on it for the last 6 months and just went to a E3D Chimera dual head setup, which I have used before with this system a year or so ago.
I just went to the Chimera and tried a simple print.
halfway through the print I got a "thermal runaway" reset.
Since I was using Octoprint, I saw several temperature spikes down during the print, when one hit zero, that was the runaway error.

Tried the print again, all things heated up and as soon as the X tried to zero, I got a "MINTEMP" reset.
Again saw thermistor spikes down on both hotends at the same time. Several experiments later I found that if I am running only one heater, the spike during the X or Y home does not MINTEMP. If I run both heaters, it does, after about 10-20mm of motion.

If I use just head 2 and the bed, I get the MINTEMP error as well.
So, it looks like some bad kind of interaction with heater 2 and movement.

This does not seem like a power supply issue, it seems like a PCB issue. Since this is the same firmware that I have always used (I use compiler directives to change firmware configs when I change print-heads), I do not think that it is a firmware configuration error either.
Because this is a Bowden Chimera, the thermistor, fan and heater wires are bundled together - which has never been a problem before...
But
I have been wrong before. Has anyone else witnessed something like this? This error is one for my notes, that's for sure.

(First Edit)
Because this looked like signal noise, I tried pulling the second thermistor from the wire bundle to the hotends and running that outside of the wire bundle. This stopped me from getting MINTEMP resets, but I still get thermistor 2 temperature dropout "spikes", just none that cause a reset. I re-routed my stepper wires further from the thermistor connections too, still get the dropouts, but do not get resets.
Hmm. It seems that I am on the right track, but this is still not working the way it used to...
()

Be well,
DLC

Edited 2 time(s). Last edit at 04/11/2021 06:34PM by dlc60.

---

Kits: Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head, TronXY X5SA Pro(E3DHemera).
Scratch: Large bed Cartesian, exchangeable heads, Linear slide Delta, Maker-Beam XL Micro Delta, 220x220CoreXY.

Well,

I have been unable to fix the problem, and am out of patience.

It seems to only occur when in motion.
It is not the thermistor, I changed that.
It is not near-by wires, I put external wires on it that did not go near stepper wires.
It seems unlikely that it is power because channel one never drops out and I am using a 360W power supply.

So, I will change the beast back to a single head Volcano and call it good.

It ran for years, time to retire the printer, it deserves a rest.

DLC

---

Kits: Folgertech Kossel 2020 upgraded E3Dv6, Anet A8 upgraded E3Dv6, Tevo Tarantula enhanced parts and dual-head, TronXY X5SA Pro(E3DHemera).
Scratch: Large bed Cartesian, exchangeable heads, Linear slide Delta, Maker-Beam XL Micro Delta, 220x220CoreXY.