Studer J37 - C3 Tape Tension Balance

a
C 3 Tape Tenslon
Balance
A
special
feature of all STUDER 37
tape recorders,
is
the tape tension balance.
Its
purpose
ls to
keep the tape tenslon across the heads,
whlch
ls
very
critical, constant
during
"record"
and
"replay"
for
all spooling
diameters that are llkely to occur ln
practlce,
It helps to smooth out any
Jerks
that mlght be caused by
bad
splices
in the tape.
At
the end of tape, or
if
the tape
breaks,
the tape tenslon balance
returns to its rest
position
and
performs
the function of the
stop
key,
It also switches
the capstan
motor
on and off.
After
threading the tape,
a
sllght
pull
on the tape will brlng the tape tension balance into its
working
position,
thereby swltchlng the capstan motor on. The record or replay keys should not
be
preised
untll
the capstan motor has had time to run up to
speed
(
app.
l0
sec.
).
The balance ls sensltlve
to the tape tension
and
operates
a stud-potentiometer. This
potentio-
meter
controls
the braklng torque in the take-off motor via
a
magnetlc
ampllfler. As
the
tape ten-
sion
balance maintalns a
very
constant tape tension, lts absolute value can be kept comparatively
Iow. This
results
in a
great
saving
of head
and
tape wear. The normal operating
tension during
"record"
or
"replay"
is app. I70
g (
6
ozs
)
before the heads.
To
facilitate cutting
and
editlng, the tape tension balance can be locked by turning it in
an anti-
clockwise
dlrectlon. This
removes
any
"give"
from
the tape
path,
Except for
the operating mode
"cuelng"
the tape tension balance is
automatlcally
returned to
lts
operatlng
position
when the
machlne is
started.
However, if
a
quick
and
clean
start
ls essential, the
tape tension balance
should
be
returned
to lts
normal
operatlng
posltlon
by hand before
pressing
the record
or
replay
key.
If
the
end
of tape swltch ls not operatlng
properly,
it can be
adjusted
-
after
loosening the
grub-
screw
-
by
slightly
rotating the
potentiometer
nousing. Wlth the tenslon
balance at
rest,
the
potentlometer
wiper should be
on
the
flrst
stud. In this
position
it
should
be
possible
to
operate
the tape speed selector keys i.e. they
should
not be electrlcally
locked. The adjusting
screw
of
the
double-draw sprlng is set correctly
when
the end of tape switch operates
as soon as
the ten-
slon balance returns to rest.
The switch
should
not operate,
however, when the tape is threaded,
regardless
of the
mode
of operation.
A dashpot connected
to the tape tenslon
balance
serves
to damp
any
mechanical oscillations,
The
red
knurled wheel on the Ieft of the dashpot
permlts
adjustment of the degree of damping. The
ad-
justment
is carrled out by aligning two holes
at
the bottom of the
cyllnder to a
greater
or lesser
degree. This is a very delicate operation
and
the disc
should
be turned
by small
fractions
only.
When removing or fitting the tape tension balance,
proceed
as
follows:
Remove electrical
connectlons.
Release Iocknut
ard
unscrew
plston
rod
(
normal right hand thread
).
Avoid
bendlng the coupling
sprlng.
Undo
the
screw ln
the
centre of the tension balance
and
carefullv
pull
the disc
off the
shaft.
The
entlre unlt
may
now be withdrawn
by undolng the three
flxing
screws.
d.