Toshiba e-STUDIO555 Service Manual page 283

5. Fuser unit error status counter control
- To enhance the safety of the fusing section unit, main-CPU provides the following protection:
When the third [C411] error has occurred after two consecutive [C411] errors, the IH coil is not
turned ON and error [C412] 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 fuser unit error
status counter "1" or below, the counter is cleared to "0".
- If the error codes [C411] to [C490] 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 fuser unit error status counter to "0".
Remark:
The fuser unit error status counter (Setting Mode (08-400)) never has values other than 0 to
29.
- If the IH coil does not turn ON and the service call [C411] or [C412] is displayed immediately after
the power is ON, ensure the fuser unit error 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" after repairing them,
then turn ON the power.
- If the fuser unit error status counter is "30" or over (e.g., 31), 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 main-CPU decides the error code and counter
value of the fuser unit error status. After turning OFF each output (the IH coil, exposure lamp,
control panel display, motors and so on), the main-CPU turns OFF the power to protect the fuser
unit.
Error code: C449 ([C] and [8])
Counter value of the fuser unit error 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
temperature 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 fuser unit
abnormality, correct the abnormality and reset the counter value (08-400) to "0" to start up the
equipment normally.
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e-STUDIO555/655/755/855
FUSER UNIT
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