Protection Mechanisms - Canon 1000 Service Manual

3. OPERATION AND TIMING

3. Protection Mechanisms

The CLC1000 is equipped with four types of protection mechanisms used to prevent malfunction of the
fixing heater.
• The CPU monitors the voltage of the thermistors THM1 and THM2 and indicates 'E000' upon
detection of an error.
• The triac short-circuit detection circuit on the AC driver PCB monitors the drive of the fixing heater; if
the fixing heater is on when it should be off, it causes the power OFF signal (PWOFF*) to go '0' so as
to cut power to the fixing heater.
• The thermistor error detection circuit on the DC controller PCB checks the thermistor for a short circuit
(230°C equivalent); if it detects a short-circuit, or if the thermistor doe not register about 50°C or more
two to three minutes after the fixing heater has turned on, it sends the power switch OFF signal
(PWOFF*) to turn off the power switch (SW2).
• If the internal temperature of the thermal switch of the upper fixing roller exceeds 230°C or the internal
temperature of the thermal switch of the lower fixing roller exceeds 230°C, the respective switch turns
off to cut off power to the fixing heater.
Once the contact of the thermal switch (TP1, TP2) opens, the thermal switch cannot be used
again unless cooled to 0°C or less. (The contact will not return to normal even after returning
to normal temperature.)
To reset 'E000',
1) Remove the cause.
2) Start service mode, and select 'FUSER > FUNCTION'.
3) Press 'E000-RLS'. (The notation <P> will change from 'ERROR' to 'BUSY' and to
'ERROR'.)
4) Turn off and then on the power switch.
3-180
COPYRIGHT © 2001 CANON INC. CANON CLC1000/1000S/3100 REV.2 MAY 2001 PRINTED IN JAPAN (IMPRIME AU JAPON)