Not sure if this helps... "If a failure occurs with the electronic control of the heater plate, overheat protection is effected by a thermal fuse on the heater plate itself.
The thermal fuse consists of a short length of solder in series with the dropper resistor track which will melt at a relatively low temperature, 268 – 302oC (514 – 576oF) causing the controllers power supply to go open circuit disconnecting power to the element."
Now I'm not sure if that also disconnects power to the controller module, aswell as the heater?
Pete, Wellington, NZ, December 2009