It was set to PID, but switching it to bang-bang didn't fix the problem. It turned out to be the MOSFET, which was getting quite hot. I replaced the RAMPS and it is working now. Thanks for your help.by spikerw - Controllers
I've just completed the construction of a Mendelmax from a kit. I've got just about everything working now except for one thing. If I try to heat the heatbed up to 110 C it shuts off before ever reaching that temperature (the LED on the board goes out and there is no voltage present at the D8 terminal). All the other electronics remain powered (e.g. there is still power getting to all the stepby spikerw - Controllers