Toshiba 4580, Service Manual

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Mar. 1999 © TOSHIBA TEC 14 - 3 6570/5570 FUSER UNIT
(9) Exit roller
After the paper is separated by the separation claw, the paper is output to the copy tray by the exit
roller of the fuser and the exit roller of the reversal unit.
(10) Exit switch
This switch detects arrival of the leading edge or trailing edge of the transfer paper at the exit roller of
the fuser. It is used for detecting paper jams in the fuser output section.
(11) Upper heat roller No.1 thermistor (center section)
The thermistor detects the temperature of the heat rollers so that it is maintained within a fixed
temperature width (actually, about 190°C) higher than the lower limit (defective fusing temperature)
and the upper limit (toner burning temperature). In other words, the thermistor controls the tempera-
ture so that the heater lamps turn ON when the heat rollers are lower than the temperature setting,
and turn OFF when they are above the temperature setting.
(12) Upper heat roller No.2 thermistor (end section)
The temperature distribution of the upper heat roller sometimes differs greatly at the center section
and end section in the lengthwise direction depending on the printing conditions. The No.2 thermistor
detects the temperature at the end section. This thermistor controls the temperature so that the
heater lamp turns OFF when either of the values detected by the No.1 or No.2 thermistor exceeds
the temperature setting.
(13) Lower heat roller thermistor
The thermistor detects the temperature so that the lower heat roller stays at around 115°C while the
copier is standing by for printing. If the lower heat roller falls below the temperature setting limit, the
upper and lower heat rollers are rotated at a speed of about 25% of high speed.
(14) Thermostat
The thermostat cuts power to the heater lamps if the upper heat roller become abnormally hot as a
result of thermistor malfunction, for example. The thermostat on this copier is for preventing abnor-
mal operation. When the thermostat detects an abnormality, the thermostat must be replaced to-
gether with the other damaged parts in the fuser.