6570/5570 FUSER UNIT
14 - 4
Mar. 1999 © TOSHIBA TEC
14.4 Heater Control Circuit
14.4.1
Temperature detection unit
To maintain the heat roller temperature, this unit detects the heat-roller temperature by thermistor-1, and
then performs heater lamp ON/OFF control.
•
The thermistor is an electrical element whose resistance decreases as its detected temperature
increases. If the thermistor is open-circuited, the control circuit erroneously determines that the fuser
temperature is extremely low and continues to energize the heater lamp. As a result, the fuser tem-
perature rises abnormally high, possibly activating the thermostat provided for safety purposes. The
CPU works to detect the breakage of the thermistor and prevents the condition mentioned above.
The following abnormalities are detected:
(1) Abnormal detection during warming up
25 sec. after the power has been turned ON, if the thermistor output voltage does not exceed 0.078
V, CALL SERVICE (C41) is displayed.
(2) Abnormal detection during stand-by/copying
If the thermistor output voltage decreases to and remains at 0.078 V or lower for 500 msec. or more,
CALL SERVICE (C43) is displayed.
(3) Thermistor status counter control
•
For improved fuser-unit safety, the CPU works as follows: After a C41 error occurs two times in
succession, even when the power is turned ON, the heater will not come ON and the C41 error will
be immediately displayed.
However, with “1” or less stored in the Thermistor status counter, if the copier becomes ready
correctly, the Thermistor status counter clears to “0”.
•
After CALL SERVICE (C41 – C45) has occurred and the thermistor, heater lamp, etc. have been
repaired (or replaced), if turning ON the power switch does not cause the heater to energize
resulting in an error, check the Thermistor status counter (08-code 400) and reset it to “0”.
Surface temperature of heat roller: 200°C (Thermistor resistance value: about 0.8 k
Ω
)
Содержание 4580
Страница 1: ...SERVICE MANUAL DIGITAL PLAIN PAPER COPIER 8070 6570 5570 4580 ...
Страница 231: ...6570 5570 DEVELOPER UNIT 12 28 Mar 1999 TOSHIBA TEC 3 Draw out the toner filter ...
Страница 252: ...8070 6570 5570 4580 FUSER UNIT 14 6A Mar 1999 TOSHIBA TEC ...
Страница 369: ...8070 6570 5570 4580 ADF 16 78 Mar 2000 TOSHIBA TEC 16 13 PC Board 1 PWA F LGC 794 ...
Страница 370: ...Mar 2000 TOSHIBA TEC 16 79 8070 6570 5570 4580 ADF 2 PWA F SEN 794 ...
Страница 374: ...Mar 1999 TOSHIBA TEC 18 1 6570 5570 PC BOARD 18 PC BOARD 1 PWA F SYS 300 ...
Страница 375: ...6570 5570 PC BOARD 18 2 Mar 1999 TOSHIBA TEC 2 PWA F MTB 300 ...
Страница 376: ...Mar 1999 TOSHIBA TEC 18 3 6570 5570 PC BOARD 3 PWA F LGC 300 ...
Страница 377: ...6570 5570 PC BOARD 18 4 Mar 1999 TOSHIBA TEC 5 PWA F MOT 300 4 PWA F ADU 300 ...
Страница 378: ...Mar 1999 TOSHIBA TEC 18 5 6570 5570 PC BOARD 6 PWA F SLG 300 7 PWA F SDV 300 ...
Страница 379: ...6570 5570 PC BOARD 18 6 Mar 1999 TOSHIBA TEC 8 PWA F PLG 300 ...