What do you do when the smoke comes out?

Went to do a print today after revamping my bed adjustments and noticed a curious thing wafting up from my printer. Turns out one of the positive pins on the green connector on my RAMPS was running a little hotter than normal. Read that ‘hot enough to melt both sides of the connector, as well as desolder the +12V pin through the RAMPS’. I’m in the process of swapping out the board, but want to see if anyone has ideas as to what might have gone wrong. That connector has two pair of fairly heavy wire going to the power supply, plus the small wires from the extruder fan. I figure if it were the fan itself the little wires would have acted like a fuse. None of the wires going to the extruder or the bed heater were hot and the pins on the connector don’t seem to touch anything.

What temp were you heating your bed to? Are you sure the fan polarity is correct, and only one fan plugged in correct?

This used to be a pretty common thing on the ramps, but it happens a lot less often now as I believe the quality of that connector is a bit better than before (little better quality knock off). It is still running close to it’s max, just trying to give a little history. I have not had this happen any more my mosfet’s pop now before the connector dies.

It could have been from power draw. The best way to combat this is heat the bed, then extruder. That way it isn’t drawing all the power at once. This is the default Marlin setting if you just run gcode, first one then the other for this exact reason. Once it is up and running the power just pulses in short spurts so no heating issues.

It also could have just been a faulty connector.

Yeah, only one fan connected to the supply connector (though I would prefer to run it off the RAMPS instead of off that supply connector), polarity is correct. I was thinking that the reason for bringing four wires over when they’re both 12V was to share the current even though it really isn’t needed for the power used (IIRC the bed pulls 11A max, the extruder 5A max, together that peaks at 184W, I’m using either 14 or 12 gauge stranded wire). I’ve got the board off and hope to see something with a closer look. I’m going to bring everything back up tomorrow with the new board in place to see if it complains as well.