Seeburg LS 1 - Switching Circuit; Oscillating Circuit; Frequency; Sas1

SERVICE MANUAL
55.22
Page
1
I.
GENERAL
The Solid
State
Auto
SPeed
Uoit,
TyPe SAS1
provides
44
cycles,
95
volts square
wave out'
put to
the
Select'O-Matic
Mechaniso
Motor
when
))-l/3
rpo.
records
are played.
The Auto
Speed
Uoit
coosists
of
a unijunction
oscillatot
with a speed
control,
an
eoitter
follower
type
buffer
stage,
a free
running
inverter and a
power relay. Pover
for
the Auto Speed Unia
is
supplied
by the
Solid State
Contiol
Center to
which
it is coooected.
2.
OPERATION
a. Swi
tching
Cireuil
Wher
a
31-L/3
rpo. record
is traosferred
to
play
positioo,
the claop
arro
switch
(6M1)
closes
to
provide a
grouod
path froo
tbe
reser
lever switch
(2M11)
which
is closed'
through
the cao
switch
(1M16),
which is also
closed,
to
pin
I
of
plug P1100,
through
the
Solid State
Control Ceoter
to
Pir
J
of
the
Auto Speed
plug
P2101. This
causes
the
power relay K2101
to energize.
f
I
SOLID
STATE
AUTO SPEED UNIT,
Type SASI
MECHAN
ISM
1.
Energizing
the
power
relay,
switches
the
oechaniso
motor froo
the 120 V,
60 cycle
line
to the
95
Y,
44 cycle
output of
the
Auto
Speed.
b. Oscillating
C ircuit
The
unijunction oscillator
produces
positive
pulses
at
a repetition
rate of
89
pulses per
second- This
rate can
be changed
by adjust-
ing the
speed
control
(R2102).
This changes
the charge time of C2101.
The
output of
the
unijunction
oscillator
is used
to drive
free
ruooing ioverter
at the desired
frequency
of
44.5 cycles. The
output
is
a
square
wave.
Adjustmen
ts
a. Frequcncy
The
desired frequeocy for a
turotable speed
ot
)3-1/)
rpm.
is
approximately
44.5 cycles
and is checked by using a strobe disc
on
the
turntable.
For
60 cycle operation,
the
part
oumber of
the strobe disc
to be
used is
508487.
For
!0
cycle operation,
the
Part
number of the strobe
disc to
be used is
t08478.
The adjustment
is oade as
follows:
Replace
a record with the
appropriate
auto
speed strobe disc.
The light
source fre-
quency must conform
to the frequency
in-
dicated
on the strobe
disc.
Press
the appropriate
oumber and letter
bunon which selects
the strobe disc
on to
the oechanism turntable.
3.
Carefully
prop
the pickup aro out
of the way.
4. Allow
the unit
to
run
approximately
three
minutes.
5.
Set
the
ootor
speed
ro
33-l/)
rpm. by adiust-
ing the
SPEED
control
oo the auto-sPeed
unit so
that the inner aod outer
bands on the
strobe disc
oove
in
opposite
directions.
6,
Remove
the
strobe
disc
aod replace
the
re cord.
3.
2.
--l
I
I
I
I
K210t
AUTO SPEED 1
L
Figute
l.
Sioplified
Switching
Circuits.