Konica Minolta bizhub C658 Service Manual page 1893

bizhub C658/C558/C458/C368/C308/C258
• When the fusing pressure roller is in the pressed state, the fusing pressure motor turns ON to release the pressure.
• The heating roller assy is rotated by the fusing motor at the same time that the IH coil is energized and stopped when the IH coil is
deenergized. The speed of the heating roller assy at this time is lower than that during a print cycle. The rotation speed at this time is
lower than the rotation speed used for printing.
• When the temperature of the fusing belt is decreased to the starting temperature of the low power mode temperature control, the IH coil
and the fusing motor are energized; when the temperature exceeds the ending temperature, the IH coil and the fusing motor are
deenergized.
• During the low power mode, ON/OFF control is repeated between the starting and ending temperatures of the low power consumption
control.
(7) Temperature control in sleep mode
• The main coil and demagnetization coil are deenergized to stop heating the fusing belt, thereby reducing power consumption in the sleep
mode.
• When the fusing motor stops running, all rollers will stop rotating.
• Sleep mode includes two types of control, which is determined depending on the time that has elapsed since printing has completed.
This control includes the engine ON sleep and the engine OFF sleep control.
• Engine ON sleep control is used when a sleep mode start instruction is received less than 1 minute after a printing has completed.
• Any running fans continue driving, but fusing temperature control is stopped.
• Engine OFF sleep control is used when a sleep mode start instruction is received 1 minute or more after a printing has completed.
• In the sleep mode, the fusing belt temperature may be decreased down to room temperature because the fusing belt is not heated. A
maximum time equivalent to the warm-up time may be required before the fusing belt temperature is increased to the print enable
temperature from the room temperature.
14.3.9 Protection from abnormal temperatures
• The machine provides protection against abnormally high temperature of the fusing unit in the following three steps.
(1) Soft protection
• When the temperature higher than the control range at heating roller assy is detected more than 1 second, the temperature is judged to
be abnormally high, and the trouble code appears.
• When the trouble code is displayed, printing will be prohibited.
Roller name
Heating roller assy Heating roller temperature sensor: TEMS
Heating roller thermistor2: TH2
Heating roller thermistor1: TH1
(2) Hard protection
• Next level is provided when the level 1 cannot detect due to CPU overrun.
• The heater relay, through the printer control board, is turned OFF in the second level operation to block the power supply to the IH coil.
• When the controlled temperature of heating roller assy is detected higher than the predetermined value, the temperature is judged to be
abnormally high, and the trouble code appears.
• Through these control procedures, the power supply to the IH coil can be shut down before the thermostat is activated in the third level. It
thereby suppresses damage to the fusing unit itself.
Roller name
Heating roller assy Heating roller temperature sensor: TEMS2
Heating roller thermistor1: TH1
Heating roller thermistor2: TH2
Heating roller thermistor3: TH3
(3) Excessive rise protection
• If the abnormal high temperature of soft protection/hard protection cannot be detected due to a faulty temperature sensor or thermistor,
thermostat blocks the power supply to the IH coil.
• The thermostat rating is 210 degrees centigrade for the heating roller thermostat. The ratings do not, represent the actual surface
temperature of the fusing belt, since the thermostats are installed in a non-contact with respect to heating roller assy.
14.3.10 IH power supply control
(1) IH power supply abnormal temperature detection
• The IH power supply unit includes a temperature fuse. This fuse prevents IH power supply troubles due to increased unit internal
temperature.
• The IH power supply unit includes a thermistor for monitoring the unit internal temperature. Control starts to lower the temperature when
the unit internal temperature has increased.
• Details of high temperature detection control
Fault name Mode
High Printing
temperature 1
O THEORY OF OPERATION bizhub C658/C558/C458/C368/C308/C258 > 14.
Sensor name: symbol
Sensor name: symbol
Control contents
Productivity decreases from 100% to 50%.
Productivity returns to 100% when a temperature of 90 degree is
detected for at least 30 seconds.
C3725 Fusing abnormally high temperature detection
(Center of the heating side)
C3726 Fusing abnormally high temperature detection
(Middle of the heating side)
C3722 Fusing abnormally high temperature detection
(Edge of the heating side)
C3725 Fusing abnormally high temperature detection
(Center of the heating side)
C3726 Fusing abnormally high temperature detection
(Middle of the heating side)
C3722 Fusing abnormally high temperature detection
(Edge of the heating side)
O-118
FUSING SECTION (bizhub C658/C558)
Trouble code
Trouble code
Code
Do Not Display