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Sansui FR-D4 - Function of Arm Position and Lifter Sensors; Control Section and Micro Computer Operation

Sansui FR-D4
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2.
Function
of
arm
position
sensor
and
lifter
position
sen-
sor
(See
Fig.
2-1, 2-2,
2-3)
e@
The
arm
position
(whether
it
is
®
on
the
arm
rest
@®
left
from
arm
rest
()
at
lead-in
position
(4)
at
end
position
of
disc)
is
de-
tected
by
arm
position
sensors
called
A
sensor
and
B
sensor
com-
posed
of
LED
and
photo-transistor.
As
shown
in
Fig.
2-2,
LED
and
photo-transistor
are
installed
on
the
upper
and
lower
sides
of
sensor
mounting
board
that
the
light
beam
from
LED
to
photo-
transistor
is
shut
off
or
passed
through,
since
screen
plate
con-
nected
to
tonearm
shaft
passes
through
the
space
between
LED
and
photo-transistor
to
cross
the
light
beam.
(See
Fig.
2-3
A)
@
When
tonearm
is;
D
on
the
arm
rest,
photo-transistors
of
A,
B
sensors
are
ON
to
be
lightened
by
LED,
®
left
from
arm
rest,
photo-transistors
of
A,
B
sensors
turn
OFF
since
the
light
beam
from
LED
is
intercepted
by
screen
plate,
8
at
Jead-in
position
of
17cm
or
30
cm
disc,
only
the
photo-transistor
of
A
sensor
be-
comes
ON
to
be
lightened
from
slit
A
or
B
shown
in
Fig.
2-3,
@)
about
to
reach
lead-out
groove,
photo-transistor
of
B
sensor
con-
tinues
turning
ON
and
OFF
to
be
lightened
from
slit
C.
When
stylus
reaches
lead-out
groove
to
finish
record
playing,
the
term
of
turning
ON
and
OFF
of
B
senser
becomes
less
than
1.3
sec.
(33-1/3
rpm)
or
less
than
1.0
sec.
(45
rpm).
(See
Fig.
2-3
B)
@
The
detection
of
arm
lifter
completely
up
position
or
down
posi-
tion
is
performed
by
C
sensor
and
D
sensor,
the
micro
switches.
The
buttons
of
these
micro
switches
are
depressed
by
the
side
surface
of
lifter
cam,
however,
when
the
arm
lifter
is
completely
rised,
the
notch
on
the
side
surface
of
lifter
cam
becomes
the
position
where
micro
switch
button
of
D
sensor
is
located
that
the
button
is
released.
When
arm
lifter
is
completely
lowered,
the
button
of
C
sensor
is
released
by
the
notch
on
the
lifter
cam.
(See
Fig.
2-2)
Fig.
2-1
Configuration
of
Mechanism
Ass'y
.)
Screen
Plate
OZ
sm
Position
Sensor
Ae
A
Sensor
=
S05
B
Sensor
Arm
Lifter
TA
Drum
:
Oe
Clutch
PI.
Lifter
Position
Sensor
nt
mech
Cate
D
Sensor—-——~------—--"
{
4
—--—-Micro
Motor
C
Sensor——_-———
Lifter
Cam
Giga
ee
~
Friction
Pulley
Py
Gear(2)
Gear(1)
Friction
Disc
Plunger
Solenoid:
Brake
Shoe
Fig.
2-3
Movement
of
Screen
Plate
and
Principal
of
Arm
Position
Detection
A.
Movement
of
Screen
Plate.
Slit
C
(for
detecting
record
end)
Slit
B
Slit
A
<—---—-LED(B
Sensor)
—-—LED(A
Sensor)
Sensor
Mounting
Board
%
CD)
Screen
plate
position
when
tonearm
is
on
its
rest,
Screen
plate
position
when
stylus
is
near
the
lead-out
groove,
(for
detecting
lead-in
position
of
17cm
disc)
(for
detecting
lead-in
position
of
30cm
disc)
FR-D4
2-3.
Control
Section
and
Operation
of
Micro
Com-
puter
(See
Block
Diagram)
e@
The
outputs
of
A
~
D
sensor
corresponding
to
the
state
of
tone-
arm
are
applied
to
input
ports
Ra
~
Ry
of
micro
computer/
MB8844
as
H
level
(5
V)
or
L
level
(0
V)
and
input
ports
Ko
~
K3
are
determined
Hor
L
by
operation
switches
(SWo;
~
SWos).
Micro
Computer
is
determined
its
operation
by
the
states
of
its
input
ports,
then
outputs
control
signals
H
or
L
from
output
ports
(Ro
~
R2,
Rg,
O03).
©
Output
port
O3
is
for
the
control
of
DD
Motor
“start”
or
“stop”
and
the
port
being
H,
DD
Motor
rotates.
Output
port
R»
con-
trols
plunger
solenoid
ON
and
OFF,
and
plunger
solenoid
is
turned
ON
so
as
to
depress
clutch
to
TA
drum
while
the
port
R,
being
L.
Output
ports
Ro,
R,
are
for
the
micro
motor
control
and
normally
the
ports
are
in
H
state.
When
Ro
turns
to
L,
micro
motor
rotates
clockwise
(CW)
and
R,
to
L,
counterclockwise
(CCW)
rotation.
If
either
of
Rg
or
Ry
becomes
L
state,
LED
701
(COMPUTER)
starts
flickering
to
operate
astabJe
multivibrator.
The
clockwise
rotation
of
micro
motor
is
corresponding
to
the
return
of
tonearm,
up
or
down
of
Jifter,
and
counterclockwise
rotation
to
lead-in
of
tonearm.
@
The
input
ports
Ra
and
Rs
of
MB8844
receive
signals
from
B
sensor
through
wave
shaping
circuit
and
A
sensor
respectively.
When
tonearm
is;
@
on
the
arm
rest,
Ra
and
Rg
are
both
in
H
state,
@
left
from
arm
rest,
Ra
and
Rs
are
L
state,
8)
re-
aching
lead-in
position
of
30
cm
or
17
cm
disc,
Rg
is
Hand
Rs
is
L,
@
reaching
lead-out
groove,
Rq
is
L
and
Rg
receives
volt-
ages
H
or
Lin
the
terms
of
less
than
1.3
sec.
(33
pm)
or
less
than
1.0
sec.
(45
rpm).
Fig.
2-2
Side
View
of
Mechanism
Ass’y
and
Movement
of
Gear
Train
A
Sensor
Tonearm
if
Screen
y———8
Sensor
‘
Arm
Lifter
Plate
ED
-—Sensor
Mounting
Board
Notch
TA
Drum
D
Sensor—————__]
Clutch
(Micro
SW)
Se
ar(2)
C
Sensor
Lifter
Cam
Gear(3)
22]
nS
a
Po
Friction
Pulte:
:
jurnger
Solenoid
Friction
Disc
Plunger
*
CW:
Clockwise
CCW:
Counter
Clockwis:
Torque
generated
by
nicro
motor
is
transmitted.
as
indicatd
by
the
arrow
B.
Arm
Position
Detection
States
of
Photo-Transistors
on
A,B
Sensor
4
-
Tonearm
Positio,
Lead-in
Position
17cm
disc
:
ve
Lead-in
Position
Record
Eid
On
the
arm
rest
30cm
disc
(Lead-ou
groove)
ON
A
Sensor
OFF
B
Sensor
:
7
OFF
an
hipses
than
Besec.( 33rpm)
Less
than
Ipssec.(45rpm)
2

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