About to try Marlin1.1.0RC4...

[ROBOCOP]

Powersupply should be in tuesday. Then i can do some tests. I didnt have the printer connected to the computer at the time to see the communication. I will do so when testing with the new PSU. The printer is a Makerfarm I3v 12" .You are correct i believe in that the original makerfarm marlin firmware didnt have thermal protection. The heatbed is a 300W heatbed with a relay switching power directly from the PSU so it does need like 25A. I have heard the LED type PSU's failing out of nowhere which does make it hard tell if was because of load . I do have a 30A fast blow fuse inline and the fuse is still intact. Also using heavy 12Ga silcone wire for the heatbed and relay. If it does turn out to be a heatbed issue that went unnoticed with the old firmware i will probably change the heatbed. 25A is a bit overkill. Probably go with a lower wattage kapton heater with aluminum heatspreader like on my other printers. Never been a fan of the PCB type anyway cause of the warping.

I know i read of some people having thermal issues with the 12" Makerfarm heatbed and toasted relays and PSU failures.

I found this thread which seems to be just like my issue.
http://forums.reprap.org/read.php?262,604700

[printbus]

I found this thread which seems to be just like my issue.
http://forums.reprap.org/read.php?262,604700

(paragraph deleted. Even here I may have been misrepresenting how the thermal runaway protection algorithm handles a change in the temperature setpoint like that person was doing. I really don't know. )

BTW, the additional link in that thread, https://github.com/MarlinFirmware/Marlin/issues/2582, says the abstract '9' correlation to the bed has been replaced with descriptive text in newer versions of Marlin. What a thought. I think I'm out at this point. I've got to stop trying to help people with firmware updates I don't use and haven't even looked at.

[lakester]

First comment: On or around line 369 in Configuration_adv.h, it looks like you can uncomment "//#define LCD_PROGRESS_BAR" to restore the functionality I think you mentioned.

Second comment: Apologies if I missed something in the preceding discussion..., but it also seems at least possible that you have a genuinely failing bed heater relay. I missed if you mentioned that the firmware was actually reporting a runaway condition..., if it was..., were the HE and bed being successfully de-powered? ..., or did the bed just sit there and cook?

FWIW, I still run the mechanical relay, but I wired it with 10Ga from the start, AND I placed the relay board (and the RUMBA for that matter) on standoffs..., to ensure airflow underneath the board(s) as well. As I recall, MF's instructions just have you screw everything down flush to the wood.