11.5.2 Overheat Protection
IC103 and Q101 form an overheat protection circuit. When the fusing lamp is
controlled within the normal range, pin 7 of IC103 stays LOW; therefore,
Q101 stays on, allowing PC402 to operate. If the hot roller temperature
reaches 240°C, the resistance of the thermistor becomes too low. At that
time, pin 7 of IC103 becomes HIGH, turning off Q101 and stopping PC402.
At the same time "E53" lights on the operation panel and the power relay
(RA401) turns off.
Even if the thermistor overheat protection fails, a thermofuse is installed in
series with the fusing lamp. If the thermofuse temperature reaches 169°C,
the thermofuse opens, removing power from the fusing lamp.
STM
2-82
FT4220/4222
Summary of Contents for FT4215
Page 1: ...FT4220 4222 4215 SERVICE TRAINING MANUAL ...
Page 12: ...SECTION 1 OVERALL MACHINE INFORMATION ...
Page 28: ...8 AC POWER AND DC POWER DISTRIBUTION FT4220 4222 1 16 STM ...
Page 31: ...SECTION 2 DETAILED SECTION DESCRIPTIONS ...
Page 114: ...SECTION 3 DOCUMENT FEEDER ...
Page 138: ...SECTION 4 SORTER ...
Page 157: ...SECTION 5 DUPLEX ...