About to try Marlin1.1.0RC4...

[ROBOCOP]

Thanks. Iv been using mesh leveling on my Robo for a while now. I got RC6 with mesh leveling all setup and running but for some reason i keep getting thermal runaway like 90% done with the print. Not sure why this is. Any ideas. Other then that its printing up until then fine. Maybe firmware issue or possibly has to do with the Z always moving now thus heating up the stepper driver more?

[printbus]

Robocop - so now you have the quandary of was it a heater/thermistor problem that put a more extensive load on the power supply, or a failing power supply that couldn't heat things properly... Others have had early failures with the LED-type power supplies, so you're not alone there. My vote would be the failing power supply couldn't maintain the high load necessary for the heat bed as the power supply warmed up. Flickering lights is a good sign of this. If the power supply output is lower than it should be, the heaters will be dissipating less heat than they should. If the power supply output is bad enough, the heaters won't be able to reach the set point, leading to the thermal runaway protection kicking in. The wrong thermistor setup would have caused the hot end temp to read low by about 15 degrees at a 200 degree setpoint. While an error, it shouldn't have been a big enough error to create the thermal runaway detection. At bed temperatures, the thermistor error would have only been a few degrees.

I've looked at the thermal runaway code in at least older versions of Marlin. I've corrected some inaccuracies in my first post. Robocop is correct that the LCD won't show which heater is the problem. If the printer is connected to host software however, the host software should be getting a thermal runaway message that includes various detail. A HEATER ID value between 0 and 8 correlates to an extruder number; a value of 9 correlates to the print bed.

Since my last post, I've realized Robocop doesn't have a MakerFarm printer. Somewhat getting back to Lakester's context and this being the MakerFarm subforum, I think a key point of note is that thermal runaway detection is disabled in MakerFarm builds, but is enabled by default in the Marlin github repository files. MakerFarm owners that get thermal runaway errors when migrating to the new Marlin should likely assume they have hardware issues that have been going undetected with their old firmware. The errors are not likely to be due to setting changes in firmware or with their slicer. To determine what is causing the thermal runaway possibility, you either need to monitor the LCD for measured temperatures that aren't staying at the set point, look at the serial messages being sent to host software, or perhaps go in and disable thermal runaway for the bed (where the need is arguable anyway) and see if that causes the error to no longer occur.