Overheat Protection - Ricoh B230 Service Manual

226 mm is reduced by 5°C after 30 seconds, and again reduced by 5°C after 60
seconds.

Overheat Protection

The CPU cuts power to the fusing lamp at the following times:
The heating roller or pressure roller temperature becomes higher than 230°C for one
second or more
SC 543 and SC 553 for the heating roller or SC 563 for the pressure roller show for this
condition.
The heating roller or pressure roller temperature reaches 250°C.
SC 544 and SC 554 for the heating roller or SC 564 for the pressure roller show for this
condition.
The following components are used if thermistor or thermopile overheat protection fails.
Two thermostats for the heating roller and two thermofuses for the pressure roller in
series with the common ground line of the fusing lamp.
If one of the thermostat temperatures becomes higher than 234°C, it opens and
cuts power to the fusing lamp.
If the other thermostat temperature becomes higher than 235°C, it also opens and
cuts power to the fusing lamp.
If either of the two thermofuse temperatures becomes higher than 154°C, the
thermofuse opens and cuts power to the fusing lamp.
These thermofuses make a series circuit.
In either case, the machine stops operation.
SM 6-69 B230/B237