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——
V. POWER SUPPLY
A. DC POWER SUPPLY |
1. Outline
When the door switch (DSW) and power
switch (SW 1) are ON, the AC power lines
are connected to the DC power supply PCB,
which supplies 30VDC, 24VDC, and 5VDC
to the copier.
The 30VDC
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 10VAC by circuits (A),
(B), and (C) of transformer T1. 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.
Fixing roller
[Sorter power
AC loads;
| heater, main
| supply
supply
motor:
Ee
Poa =
4---
4
.
u
1
a
{
ea
+ +
AC driver:
detection
circuit
DCOFF
!
5
lm
i
+—~
30V
gS
és
tT
3
|
=
t_. 5v
DC power supply
Zero-cross
signal
generator
Zero-cross signal
- DC controiler PCB
q
Figure 3-39
COPYRIGHT © 1988-CAHON IWC. .
CANON MP-1215 HEV.0 MAR. 1968 PRINTED Hi JAPAN (IMPRIME AU JAPON)
3-35
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