RE: Thermal anomaly on firmware 3.12.2
In my case, problem solved with new Einsy board (manufactured on 2017). The problem is out and printer is working with new board and "old" (previously changed as BAD) components like thermistor, hotend heater and whole hotend. Whole problem was consulted via chat with Prusa support. Probles was not on firmware side.
RE: Thermal anomaly on firmware 3.12.2
I've had this problem off and on since upgrading firmware. However, I now believe most of my problem was the result of degraded printed parts in the nozzle area as a result of printing at high temps (nylon / PA) and frequent nozzle changes. Originally, Prusa recommended turning the hot end slightly when changing nozzles (this is no longer recommended). When doing this, the heater block can contact the fan shroud, which can melt / destroy / deform the shroud. I've since reprinted these parts and no longer turn the hotend when changing nozzles. Haven't printed a lot but so far seems to be working ok.
Since the original Prusa parts are PETG and nylon prints at higher temps than PETG, there's a lot of opportunity for screw-ups around the heaterblock. I'm planning on reprinting some of those parts in nylon when I get caught up and have a bit more time.
RE: Thermal anomaly on firmware 3.12.2
As I switched yesterday heater and thermistor without solving the problem, I switched this morning the Einsy board (had a spare one) - new board is version 1.1b, the old one 1.1a - both are "Prusa" OEM boards (orange).
I let the printer work all day and: NO PROBLEM AT ALL. Did some printing in PLA and mostly PETG.
In my case, problem solved with new Einsy board (manufactured on 2017). The problem is out and printer is working with new board and "old" (previously changed as BAD) components like thermistor, hotend heater and whole hotend. Whole problem was consulted via chat with Prusa support. Probles was not on firmware side.
RE: Thermal anomaly on firmware 3.12.2
The thermal model protection can be disabled by connecting the printer to your computer (Octoprint, PuTTY...), and sending M310 S0. An additional M500 will save the setting and the Thermal model protection will remain disabled after the next restart.