User manual

95.08.23.11.30
Color LaserWriter 12/600 PS Basics & Theory 1–115
Fuser
Assembly
Errors
In order to prevent the fuser heater from malfunctioning, the printer
provides the following three error detection functions. Full description
of these functions are on the following pages.
Error Type A
The CPU monitors the voltage of the fuser temperature detect signal
(
THI). If it detects any abnormal value, it will notify the I/O controller
as a fuser heater error and then shut off the power supplied to the heater.
Error Type B
If the fuser temperature rises abnormally and the temperature detected
by the thermistor exceeds 217°C, the safety circuit will shut off the
power supplied to the fuser heater irrespective of the output from the
CPU. Simultaneously, the CPU recognizes it as a power supply error
and notifies the I/O controller.
Error Type C
If the fuser temperature abnormally increases and the temperature of
the thermoswitch exceeds about 230°C, the thermoswitch will be
turned off to shut off the power supplied to the fuser heater.