Heatbed short?
Hello everyone!
I’ve had my mk3s for nearly a year now, and have recently run into an issue.
I was having issues with the bed heater shutting off soon after I start a print. I checked the connectors on the back of the bed, and noticed the angled cable cover I printed (to keep the wires from pressing against the back of the Lack enclosure) had heated up enough to become warped.
I opened the Einsy box, and quickly realized the negative bed connector insulation was burnt, the terminal discolored and slightly blackened.
I had the bed heat set for PETG,
I am concerned about the board itself, I can replace the terminal on the wire, but I don’t think that was the source of the problem.
Has anyone else had this happen?
The printer itself is stock, no wiring mods, or anything more than the angled bed connector. I have a separately powered fan attached to the extruder motor to keep it from overheating, but that’s another issue entirely. 
RE: Heatbed short?
I just had this exact thing happen - same issue, angled connector etc etc.. Prusa support said wire must have loosened. No matter, I did replace the wire and it all works again so yours probably will as well. 🙂
They did have me check the board with a multimeter and it was fine so that might be something you could check as well to be sure.
RE: Heatbed short?
I personally think Prusa has had some bad crimps. Over time, as they oxidize the resistance builds up. That results in what you see.
When you replace the connector and maybe the cable - invest in a decent crimper and do a better job than the factory.
Not sure I feel about solder - but start with a good crimp. And get the proper size connectors.
Your board should be fine.
RE: Heatbed short?
@robert-rmm200
that makes sense - my connectors were not loose when I checked em, but I figured they knew better than I. 😛