Um
ein Lösen
des Selbsthaltekontaktes
S
'i2
des Start-Magneten M
1 zu
erreichen,
ist
auf der
Verteilerplatte
eine Schaltung
untergebracht,
die
nach
Loslassen
der Stop-Taste
S
5 oder
spätestens
beim Umschalten
des
Kurvenrad-Dauerspiel-Schalters
S
9
den Start-Magneten
M
j
für kurze
Zeit
stromlos
macht.
Normalerweise
ist
di ese Strom
unterbrechu
ngsschaltu
ng du rchgescha
ltet.
Die Basis
von T
945'l
wird
über R
9452 auf
positivem
Potential
gehal-
ten.
Wird
die Stop-Taste
S
5
gedrückt,
so
wird
über R
9453 der Konden-
sator
C
9454
entladen.
Nach
Loslassen
der Stop-Taste
oder Umschalten
des Kurvenradschalters
S
g
kann
sich C
9454 über R
94b2 aufladen.
Damit
bleibt
der Transistor
T
9451 bis zum
Erreichen'
seiner Schalt-
schwelle
von
ca.
5
V
gesperrt.
lnnerhalb
dieses
Zeitraumes
muß
der
Anker
des Start-Magneten
M
'l
abgefallen
sein,
damit
die
Stop-Funktion
ordnungsgemäß ablaufen
kan
n.
Diese Zeitspanne
beträgt
0,075
s bis 0,3
s.
Die
Diode D
9459 ermöglicht
den Anzug
des Start-Magneten
I\/l
1 bei
Stop-Betätigu
ng.
Functiona!
description
Motor
control
The
generator
G supplies the motor
control
with
a speed-pro-
portional
frequency
which
is cleared
of disturbing
harmonics
by C
9O1 1 and is routed
to transistor
T
9005 via C
g0,l2.
Tran-
sistor T
9O05 amplif
ies the voltage by
a
factor
of
180. lC I
9005
which
f
unctions as
an operational
amplif
ier receives
its working
point
from
the voltage
distributors R
90.1 9
and
C
g013.
The
positive
feedback
through
R
9020 accelerates
the
swjtchover
process
of
the operational amplifier
in
the
pulse
of the
generator
frequency
resulting
in steep flanked
pulses
at
pin
7
which control
the
phase
comparison
circuit I
9003 via T
9002. The
differenti-
ated
pulses
through
C
9014,
R
9021
and R
9022
briefly
control
T
9006,
resulting in the
capacitor
C 9O1 5
discharging via R
9O26.
Depending
on the
selected speed
the
capacitor
C 901 5
is
charged
in
the direction of earth
through R
9024,
R
9025, R
9027 and
R
9028. At
the speed of
33 only R
9027 and R
9028
are effec-
tive.
At the
speed of
45
f
9007
becomes
conductive
so that
the
resistors R
9024 and R
9025 are also
included
in the circuit.
Therefore,
when
carrying
out a speed
comparison
the
speed 33
should
always be
adjusted
before the
speed 45. The
sawtooth-
shaped voltage
at
pin
2 of I
9005 is compared
to the
medium
voltage formed
by R
9029
and
R
9040. lf the voltage falls
short
of the medium
voltage
a
positlve
output
pulse
appears
at
pin
1
at I
9005.
This
pulse
reaches T
9O0B via
the differentiating
circuit
R
9031
,
C
901
7 and
R
9032 whereby
C 901 B discharges
to the
0.7 V
produced
by the voltage
distributor R
9034,
R
9035.
Depending upon
pulse
duration C
9018 is recharged Through
D
9007, D
9008
and R
9033,
R
9036. This
reaches the
filter
circuit R
9037,
C
9019 which controls
T 90Og
which acts as a
Darlington
circuit and
therefore also controls
the motor
voltage.
0uartz
circuit
:
The
quartz
crystal
oscillator consisting
of
T
9001,
B
900.i
,
R
9002,
C
9001
.
. .
C
9003 and
the direct wave
quartz
crystal
with
4608
MHz,
reaches
via
pin
9 the distributor I
9OO1 which
can be
programmed.
lf
thespeed switchoverS 7
switch is in the
"33"
position
then the
input data of
the inputs
P1
up
to
PB
have the
following
bit
pattern:
H
L
H
L
H
L H H. This
correspondstoa
decimal
figure
of 135 where
the
values
of
Pl
-
Pg
correspond
to
the numbers
1,2,4,8,1O,20,40,80. ln
position
"45"
thedeci-
mal figure
100 is represented by
the bit
pattern
(Pl
-
Pg)
L L L
L L H L H. ln
this case
the
frequencies
?4.13kH2
or 46.08 kHz
appear at
the output
pin
15
of
I
9OO1
{O
8)_ These
frequencies
are
divided
by 512
l29l
by I
9002 whereby the
working f
requen-
cies
of 66 213
Hz
or 9O
Hz
or
90
Hz
are
produced
(pin
12)- The
output reaches
the
phase
comparison
circuit which
is
formed
from
the two D
-
flip-flops 19003,
R
9010 and D
9001.
The
reference
frequency whlch
corresponds
to the first
speed
is ob
tained from I
9o05/pin 7 which
is
connected
to an
inverter by
T
9002,
F
9005,
R
9006 and
R
9007.
The
two
ourputs
of the
phase
comparator
circuit contain
the
data of the
phase
angle
from
-360o
up
to
+3600
in the
form
of differing
pulse
widths.
Die Diode
D
9460 verhindert
die
Auf
ladung von C
g454
über
den
Zweig
von
D
9459. C
9454
soll
sich
ja
über R
9452
aufladen.
D
9456 hebt
das
Emitterpotential
zur
Funktionssicherheit
zusätzlich
an
D
9455 verhindert
das Ansprechen
des Start-Magneten
beim manuellen
E
inschalten
des Gerätes.
D
9457
und D
9458 unterdrücken
die beim Abschalten
entstehenden
negativen
Spannungsspitzen
an den Magneten.
Muting
Das
N
F-Signal
gelangt
vom
Abtaster
an den
Stummschalter
S 1 1
,
der
in
Grundstellung
des
Kurvenrades geöffnet
ist.
parallel
zum S
.l
1
liegen die
Kontakte
des
Stummschaltrelais
RL 940i. Dieses
Relais
wird über
die
Schalter
S 4
-
Start, S
g
*
Continous
Play
und
S 6
-
Lift angesteuert.
Das
Relais
bleibt ca.
1,2
Sekunden
in Arbeitsstejlung.
These
signals are
decoupled
by
the diodes
D
9002
and D
gOO3
and
are adapted
to
suit the
control
circuitry
by
the
resistors
R
901 1,
R
9O.i2
in
such a way
that a
synchronous
speed
is
maintained
within
a tolerance
of
!
3 %. The
synchronization
is
achieved
by
a
positive
current
from
R
gO11
flowing
into
the
speed
governoring
capacitor
C
9015 when
the
phase
angle
is
leading. This
slightly
lowers
the
sawtooth
voltages
(measured
from
+12
V)
resulting
in
a
lowering
of
the motor
speed.
lf the
phase
angle
is lagging
a negative
current
via R
g0l2
flows
into
the capacitor
C
9015
resulting
in an
increase
of the
motor
speed"
This
therefore
ensures that
the
correct
speed
is maintained.
Pitch
The
voltage
drop
at
R
9039
is
proportional
to
the motor current
and controls
the medium
voltage at
pin
3 of
lC
900b
via
R
gO40
compensating
the drop
in speed which
depends
on the
torque.
lf.
f
orexample,
transistorT
90i0 is
strongly
forward
biased
(Vc
5.3 V)
the effect
is neutralized
through D
90O9 and R
9041.
For
pitch
adjustment,
the medium
voltage
at
pin
3 of
I
g005
can
be slightly
shifted to
+
or
-
by the
potentiometer
R
gO42
through
R
9030. ln
thisway
the speed
adjustment
lies in the
range!5,'/o.
This
adjustment
is only
possible
in the
position
"pitch"
and
in
quartz
mode.
This
is stored by
a
quartz/pitch
srvitch
S 2.
Stroboscope
The exact
pulses
for
the stroboscope
are
obtained
as follows:
The frequency
of the
distributor I
9O02 is differentiated
by
R
9009, C
9008 and R
9O13 and
reaches
the base
of T
9003
through
the
diode D
9004_ This
is transferred
for a
short
period
in a
reversed
biased
state whereby
a current
is set up at
the base
of T
9004 resulting
in a
0.7 V lower
voltaqe
at R
gO16
than
at
the base.
The constant
base voltage
also ensures
a
pulse
voltage
through
the
LED'S D
9005 and
D
9006. The
light
duration
mainly
depends on
C
9008
and R
901 3. The flashing
frequency
at
33 rpm
is 66 213 Hz
and at
45
rpm 90 Hz; each
value has
the
precision
of a
quartz
crystal.
Display
The display
serves
to visually
indicate the
following
conditions:
33 and
45
rpm speed display,
quartz
or
pitch
mode. The
two
LED's for the 33 and 45 rpm speed
indication light up alternately
depending on the switch setting.
lf there
is
an
excessivetorque load on
the
platter,
and
in the start
up
phase,
the anode
potential
is
connected to
ground
by T
91 07,
as the
result
of which they
are
extinguished.
The two LED's
for
quarlz
or
pitch
mode also
light up
depending
on the
switch setting S
2.
^
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