Konica Minolta bizhub C250 Service Manual page 143

20. Fusing section
20.3.11 Protecting from the abnormally high temperature
The machine provides protection against abnormally high temperature of the fusing unit in
the following three steps.
Details for each control are described in the following sections.
Level Name
Software
Level 1
protection
Hardware
Level 2
protection
Thermostat
Level
3
protection
110
• It detects the high temperature troubles which most likely occur.
• When the heating roller thermistor/1 and the fusing pressure roller ther-
mistor/1 detect abnormally high temperature, the trouble code for the
abnormally high temperature will be displayed, and the printing will be pro-
hibited.
• When the level 1 protect is not executed for some reason, level 2 protect
will be performed.
• When the heating roller thermistor/3 and fusing pressure roller thermistor/2
detect abnormally high temperature, the heater lamp relay will be forced to
be OFF, and will shut down power supply for each heater lamp.
• When the heater relay stays OFF for specified period of time, the trouble
code for the abnormally high temperature will be displayed, and the print-
ing will be prohibited.
• When the level 2 protect is not executed for some reason, level 3 protect
will be performed.
• When the soft protect or hard protect control is not executed for some rea-
son such as malfunction of the thermistor, the heating thermostat/fusing
pressure thermostat will detect the abnormally high temperature and the
power for each heater lamp will be OFF.
TS2
TS1 H1
H2
RY1
Theory of operation ver. 3.0 Aug. 2006
Control
TH1
TH3
H3
TH2
TH4
TH5
4038T2C145AA