I spent the first two weeks of February waiting for the hotends to arrive. In the meantime, I did some tweaking and what-not of firmware, and got acquainted (as best I could) with mesh bed leveling, the Marlin firmware, and getting my heated bed working properly. That last bit…. there was magic smoke involved.
So I was trying to autotune the PID for the heated bed, following the instructions in the Marlin sourcecode, and pushing ever closer to the elusive 100 degree mark. Around 92 degrees on the heat bed, I started to smell what I can only describe as burning chineesium. I cut the power to the machine, waited, and turned it back on.
The heat-bed LED lit up. Even though in software it was turned off. Huh. I took a look at the RAMPS board.