RUMBA Heating Failed

Hello,

I've been having this issue recently with my RUMBA control board when I want to start a print, and I begin to heat my PCB MK2 heated bed. When the bed begins to heat, it is able to heat up until about 50 degrees Celsius, but then progress halts and Marlin reports on the display screen "Heating Failed: Please Reset." I did some probing with my multimeter, and it seems like once the printer reaches 50 degrees there is a significant drop in voltage output to the heated bed. Also by the time it stops heating, the 11A fuse that is mounted on the RUMBA is scalding hot and extremely pliable. The fuse gets hot enough that it hurts my hand to touch.

I'm confident this is not a problem with the Marlin programming, I haven't changed any settings in months and they have been working fine ever since then, up until this problem arose a couple days ago. Do I need to replace the fuse?

Thanks!
Sam

Hit the fuse with a fan

If that helps, it probably time to replace the polyfuse

Failing that the bed has potentially started drawing more current, Most common cause is shorted tracks. Mounting posts and the like wearing threw the thin coating and touching copper...