Toshiba e-STUDIO 2555C Service Manual page 122

Temperature detection circuit
A thermistor is a device whose resistance varies according to the detected temperature. The ASIC
detects voltages output from this device, and judges whether the operation of the fuser unit is normal or
abnormal from the changes in voltages.
If any of the thermistors is broken, the control circuit judges that the surface temperature of the fuser
belt is extremely low and keeps turning the IH circuit ON. As a result, the surface temperature of the
fuser belt rises, and this possibly activates a thermostat which is a safety protection device. To prevent
this in advance, the ASIC detects whether each thermistor is broken or not.
Also, the control circuit constantly monitors the surface temperature of the fuser belt to prevent them
from excessive heating caused by abnormalities in circuits or thermistors, and automatically shuts OFF
power supply when the surface temperature exceeds the preset temperature.
e-STUDIO2555C/3055C/3555C/4555C/5055C © 2012-2013 TOSHIBA TEC CORPORATION All rights reserved
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