If the thermistor overheat protection fails, there is a thermostat [1] that also monitors the hot roller temperature.
The thermostat [1] monitors the external temperature of the hot roller.
If the temperature of the thermostat becomes greater than 185 °C, the thermostat opens, removing power from the fusing lamp. At this time, the machine stops.
The thermistor (center) [2] monitors the surface temperature of the hot roller.
If the temperature becomes greater than 250 °C, the CPU cuts off the power to the fusing lamp.
The thermistor (edge) [3] also monitors the surface temperature of the hot roller.
If the temperature becomes greater than 250 °C, the CPU cuts off the power to the fusing lamp. At this time, SC543 will be generated.
The customer engineer can use the SP mode (5-810-001) to make the machine recover from the SC543 status.