Canon GP215 Service Manual page 175

3. Controlling the Supply Power to the Fixing Heater
The temperature of the fixing heater is controlled by controlling the power supplied to the fixing heater.
The plane-shaped heater used for the fixing heater tends to be subject to variation because of pro-
duction factors.
In view of this, you must enter the resistance in service mode (*3*) whenever you have replaced the fix-
ing assembly so that the microprocessor on the DC controller PCB executes appropriate power control.
Caution
Caution:
The fixing heater resistance is entered in service mode at the factory; do not change it unless you
have replaced the fixing assembly.
The power to the fixing heater is controlled by means of phase power control.
The microprocessor controls the output timing of the fixing heater drive signal (HTRD) so that power
appropriate to the target temperature of the fixing heater may be supplied (through phase control).
Zero cross signal
Fixing heater drive signal
Supply power to fixing heater
COPYRIGHT © 1996 CANON INC.
A C
Heater OFF
Power applied to heater
Figure 3-641
CANON GP215/200 REV.0 JULY 1996 PRINTED IN JAPAN (IMPRIME AU JAPON)
3. OPERATIONS AND TIMING
3–121