Canon PC300 Service Manual page 71

Ea OPERATIONS AND TIMIN
8. Power Supply PCB
The copier's power supply is a compos-
ite power supply in which one main trans-
former (T106) supplies DC power as well as
power for high voitage and scanning lamp.
AC power is 'supplied to the DC power
supply when the power switch and door
switch are turned ON.
The DC power supply generates +24 V
and +5 V.
For auto power-off, the microprocessor
causes the relay (RL101) to go OFF, thus
cutting power supply.
The copier is equipped with a sub power
supply which provides the microprocessor
with +5VDCL power for about 5 minutes
after a condition associated 'EQ' occurs; dur-
ing this period, the copier is prevented from
going ON to prevent damage by overheating
the fixing heater.
jlerances for the DC power supply _
lows: .
L$ 2%
Us 422 V to +46 V
45.V 410%
3-44 COPYRIGHT © 1904 CANON INC.
C. Protection Mechanism for
Power Supply Circuit
The DC power supply circuit's AC power
supply input is equipped with a fuse. The
fuse blows if an overcurrent flows because
of a short circuit in the 24V power, thus shut-
ting out the output from the AC power supply
circuit. If this happens, disconnect the
copier's power cord, correct the cause of the
problem, and replace the fuse.
If the microprocessor detects an error on
the AC or 24VDC line of the main trans-
former (T106), it causes the relay to. go OFF,
thus cutting the power output. If this hap-
pens, remove the cause and switch the copi-
er ON to reset.
CANON PC300/920/325, FC210/290 REV.O JULY 1994 PRINTED IN JAPAN (IMPRIME AU JAPON)