Toshiba e-STUDIO350 Service Manual page 234

(5) Thermistor/Heater status counter control
• To enhance the safety of the fusing section unit, CPU provides the following protection: When the
third [C410] error has occurred after two consecutive [C410] errors, the IH coil is not turned ON
and error [C410] is displayed immediately even if an operator turns OFF the power and back ON.
However, if the equipment goes into a ready state normally with the thermistor/heater status
counter "1" or below, the counter is cleared to "0".
• If the error codes [C410] to [C450] are displayed and still not cleared even though the thermistor,
thermostat and IH coil have been repaired (and the power ON/OFF does not clear the error),
check the Setting Mode (08-400) to set the thermistor/heater status counter to "0".
Reference
*The thermistor/heater status counter never has values other than 0-18.
• If the IH coil does not turn ON and the service call [C410] is displayed immediately after the
power is ON, ensure the thermistor/heater status counter is "2" or over. If it is "2" or over, be
sure to check the thermistor, thermostat and IH coil. Reset the counter to "0" (Setting Mode
(08-400)) after repairing them, then turn ON the power.
• If the thermistor/heater status counter is "19" or over (e.g., 21), the data in NVRAM or NVRAM
itself may possibly have been ruined due to causes such as leakage from the chargers. Check
the bias, high-voltage transformers and charge wires to see if any of them is defective, and
also look through all the data in the NVRAM.
• When the thermistors detect overheating, the CPU decides the error code and counter value
13
of the fuser roller thermistor status. After turning OFF each output (the IH coil, exposure lamp,
control panel display, motors and so on), the CPU turns OFF the power to protect the fuser
unit.
Error code: C440 ([C] and [8])
Counter value of the fuser roller thermistor status: 9 (08-400)
Thermistors continue detecting the abnormal temperature even after the error codes and counter
values are decided. Even if the power is turned ON immediately, it is automatically turned OFF
again when the surface temperature of the fuser roller is still higher than the abnormal tem-
perature detected.
Wait until the surface temperature of the fuser roller is lowered enough, and turn ON the power
to check the counter value while it is turned OFF again. After confirming that it is the IH control
abnormality, correct the abnormality and clear the counter value (08-400) to "0" to start up the
equipment normally.
e-STUDIO350/450 FUSER UNIT / PAPER EXIT SECTION 13 - 10 November 2003 © TOSHIBA TEC