Sharp AR-RF3 (serv.man2) Service Manual ▷ View online
AR-RF3 EXPLANATION OF ELECTRICAL SECTION 9 - 4
(3) Original delivery motor (DEM)
This circuit controls the DEM rotation, stop, rotation direction and
motor current. It is composed of the CPU (IC6), DA converter (IC2),
constant current chopper type driver IC (IC8), etc.
motor current. It is composed of the CPU (IC6), DA converter (IC2),
constant current chopper type driver IC (IC8), etc.
The stepping motor drive excitation pattern signal that is output from
the CPU (pins IC6-76 to IC6-79) controls the speed and direction of the
motor.
the CPU (pins IC6-76 to IC6-79) controls the speed and direction of the
motor.
The analog signal output from DA converter (pin IC2-7) is divided at
R37 and R34 to provide a fixed voltage.
R37 and R34 to provide a fixed voltage.
The current value for the motor is set when this split voltage is input to
pin IC10-3 and pin 14.
pin IC10-3 and pin 14.
D-(3) Delivery motor drive circuit
E. Reset circuit
This circuit generates a reset signal to the CPU.
IC12 functions to reset the CPU when the power is turned ON, and
also when the +5V becomes lower than the suitable voltage range.
also when the +5V becomes lower than the suitable voltage range.
After the power is turned on, the reset condition is maintained for a
fixed period of time after the current voltage reaches 4.3V.
fixed period of time after the current voltage reaches 4.3V.
The WDT function is assigned to IC12, as well, and monitors runaway
or other abnormalities in the CPU.
or other abnormalities in the CPU.
E Reset circuit
F. Rush current limiting circuit
When the open/close switches AOSW and DFSW are turned ON/OFF,
this circuit limits the flow of a rush current to the current regeneration
condensers in the motor drive circuits to a value lower than a fixed
value.
this circuit limits the flow of a rush current to the current regeneration
condensers in the motor drive circuits to a value lower than a fixed
value.
It is formed of posistor PTH1 as the current limiter and FET Q1 which
allows the flow of a steady current.
allows the flow of a steady current.
For a fixed period of time after the open/close switch is closed,
because the FET status is OFF, the current flow is to the posistor.
because the FET status is OFF, the current flow is to the posistor.
Following this, when the FET becomes ON triggered by the ON signal
from the port, the current to the posistor can then be fed to the FET,
canceling the current limiter.
from the port, the current to the posistor can then be fed to the FET,
canceling the current limiter.
F Rush current limiting circuit
Delivery MOT
DEM
DEM
Main reset
AR-RF3 EXPLANATION OF ELECTRICAL SECTION 9 - 5
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
Or
iginal width v
o
lume
Or
iginal
length
sensor 1
Or
iginal
length
sensor 2
Document
fe
ed open
sensor
Or
iginal
empty
sensor
Or
iginal
width
sensor
Or
iginal timing sensor
Or
iginal resist sensor
Or
iginal re
ve
rse sensor
Document e
xit sensor
F
ront
open sensor
Document e
xit co
ver sensor
ADF open SW
F
or IC6
F
or IC3
Document f
eed co
ver sensor
Mode 5
P
o
w
er +5V
P
o
w
er +24V
F
or IC7
F
or IC11
F
or IC4
F
or IC5
F
or IC1
F
or IC2
Document e
xit MO
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Tr
anspor
t MO
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Document
fe
ed MO
T
Indicator LED
2.
Cir
c
uit diagram
AR-RF3 EXPLANATION OF ELECTRICAL SECTION 9 - 5
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
Or
iginal width v
o
lume
Or
iginal
length
sensor 1
Or
iginal
length
sensor 2
Document
fe
ed open
sensor
Or
iginal
empty
sensor
Or
iginal
width
sensor
Or
iginal timing sensor
Or
iginal resist sensor
Or
iginal re
ve
rse sensor
Document e
xit sensor
F
ront
open sensor
Document e
xit co
ver sensor
ADF open SW
F
or IC6
F
or IC3
Document f
eed co
ver sensor
Mode 5
P
o
w
er +5V
P
o
w
er +24V
F
or IC7
F
or IC11
F
or IC4
F
or IC5
F
or IC1
F
or IC2
Document e
xit MO
T
Tr
anspor
t MO
T
Document
fe
ed MO
T
Indicator LED
2.
Cir
c
uit diagram
AR-RF3 EXPLANATION OF ELECTRICAL SECTION 9 - 5
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
A
B
C
D
876
5
4
3
21
1
2
3
4
5
6
7
8
D
C
B
A
Or
iginal width v
o
lume
Or
iginal
length
sensor 1
Or
iginal
length
sensor 2
Document
fe
ed open
sensor
Or
iginal
empty
sensor
Or
iginal
width
sensor
Or
iginal timing sensor
Or
iginal resist sensor
Or
iginal re
ve
rse sensor
Document e
xit sensor
F
ront
open sensor
Document e
xit co
ver sensor
ADF open SW
F
or IC6
F
or IC3
Document f
eed co
ver sensor
Mode 5
P
o
w
er +5V
P
o
w
er +24V
F
or IC7
F
or IC11
F
or IC4
F
or IC5
F
or IC1
F
or IC2
Document e
xit MO
T
Tr
anspor
t MO
T
Document
fe
ed MO
T
Indicator LED
2.
Cir
c
uit diagram
