Canon NP6330 Service Manual page 227

CHAPTER 6 FIXING SYSTEM
b. Protection with the Signals from the SSR
If the fixing heater continues to remain on because of a short circuit in the SSR, the
DC controller PCB generates the error auto power-off signal (PWOFF*) to turn off the
power switch.
The copier's fixing heater drive SSR sends the SSR drive signal (MSSRD, SSSRD)
to the DC controller PCB when the SSR is ON; the DC controller PCB also monitors the
heater drive command (MHRD, SHRD) and the SSR drive signal (MSSRD, SSSRD) at
the same time.
If the main SSR drive signal (MSSRD) is '1' when the main heater drive command
(MHRD) is '0', the DC controller PCB will assume the condition as an error in the SSR
and will indicate 'E004' on the control panel. In about 2 sec thereafter, it generates the
error auto power-off signal (PWOFF*) to turn off the power switch.
c. Protection with a Thermistor
If the internal temperature of the thermal switch (TSW1) exceeds about 208°C, the
thermal switch turns OFF to cut off the power to the fixing heater.
If the thermal switch turns OFF, the error auto power-off signal (PWOFF*) will be
generated in about 1.5 sec to turn off the power switch.
Reference:
Once its contact opens, the thermal switch (TSW1) will not return to normal even at
ambient temperature. It may be used once again by cooling it to 0°C or less.
d. Recovery after Activation of the Protection Mechanism
If the error auto power-off signal (PWOFF*) has been generated, remove the cause,
and turn on the power switch to recover.
If 'E000', 'E001', 'E002', 'E003', or'E800' has been indicated, remove the cause, and
execute '401' in service mode [4] to recover.
Reference:
When selected in user mode, "auto power-off" will also turn off the power switch
when activated. To distinguish from such "auto power-off," this manual refers to the
foregoing auto power-off as "error auto power-off."
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COPYRIGHT © 1997 CANON INC. CANON NP6330 REV.0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)