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V.
POWER
SUPPLY
A. DC POWER
SUPPLY
1. Outline
When the door switch (DSW) and power
switch (SWl)
are ON, the AC power lines
are connected to the DC power supply PCB,
which supplies BOVDC, 24VDC. and 5VDC
to the copier.
The BOVDC supply drives the scanner
fan motor (M2), and the 24VDC
supply is
used for fans,
solenoids,
etc., and also
powers the HVT. The 5VDC supply is used
for the sensors and also the ICs and other
devices on the DC controller PCB.
B.
DC POWER
SUPPLY
CIRCUITS
The AC supply voltage
is reduced to
29VAC.
23VAC.
and 1 OVAC by circuits (A),
(B), and (C) of transformer
Tl.
These volt-
ages are rectified by the DC power supply
PCB,
to
provide,
respectively,
24VDC.
30VDC,
and 5VDC.
If the output voltages of the 24VDC and
5VDC power supplies fluctuate, the copier
may misoperate.
Consequently,
regulators
are used in both of these supplies to prevent
,--
voltage fluctuations.
The 24VDC
circuit has an overcurrent
detection
circuit.
If excessive
current
is
drawn, the transistor in the detection circuit
will,go
ON, causing the 24VDC
output to
stop. Also, the DC controller monitors the
24VDC voltage continuously. If this voltage
fluctuates
due to an abnormality,
the DC
controller
will output
a 24V-OFF
signal
(DCOFF) to stop the 24V output.
When the 24V output stops, the copier
will stop operating.
To reset the 24V output, open the front
door, remove the cause of the stoppage,
then close the door. If the door is opened
and closed repeatedly without clearing the
problem, the fuse on the DC power supply
PCB may blow.
The DC power supply PCB generates a
continual
zero-cross signal which
is out-
--.
putted to the DC controller. It is used as a
timing signal for AE operations.
3 - 32
I !
I I
II
I
I&
I
l---+----i------J
o-k+4
AC driver
SW1
DSW
Cfrcuit
breaker
-~-
--
~-
7
r---------
COPYRIGHT
0
1988 CANON INC
CANON HP-101511215S
AB.0
OCT.
1988 PAINTEO
IN JAilN
[IMPAIM~
AU JAPONI
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