Studer J37 - Recommended Test Instruments; E1 Alignment of Playback Channel

It
is recommended that the tests
and allgnments on the
STUDER
J-37,
should be carrled
out in the
followlng
order and uslng
the
test lnstruments
and
tools mentloned
hereafter:
Recommended Test Instruments
The signal
generator
can be
of any make but
should have low distortlon.
Valve-voltmeters of
any
make,
but
preferably
for
slgnal to noise measurement
the
SIEMENS & HALSKE
Rei
U
33, or the
GENERAL
RADIO
DISTORTION
AND NOISE METER,
Type I932-A.
7
I/2
fps and 15 ips test tapes.
Wow
and
flutter
meter EMT 420
with
high
speed
pen
recorder
EMT IIe Ib, or
set
of fllters
EMT 421 or wow
and
flutter-
meter EMT 4I4 ot 418,
both ln conjunction
with the high
speed
pen
recorder
EMT
He
Ib.
Dlstortion meter
EMT 126.
De*magnetlser
of any make.
Wave anal.yser or 1000
c.
p.
s . band
pass -
fllter
of
anv
make
E I
Alignment of Playback
Channel
It
is recommended
to
proceed
in
the following
order:
-
switch off
recorder
and de-magnetlse the
tape
path
-
thread test tape
ard
switch to
,'playback"
-
set the output
voltage of the
playback
amplifier
to
the deslred Ievel by
means of
the
pre-set gain
control
(
max.
4.4
V
)
The two
poteraiometers
for
setting the levels
at
7 7//2
lps and 15 ips
are
electrlcally
independent
of one
another.
E la
Setting the
Azlmuth of the Playback
Head for
Maximum
Output
Play the
azimuth sectlon of the test tape
and measure the output
voltages of
channels I
and
4
at
the
same
time
. Adjust the screw C
(
fig
. 6
)
for
maximum output
on both channels
. If the
maximum
output of the two
channels occurs
at dlfferent
points.
an lnbetween setting
should be chosen
which
glves
an equal relative voltage drop for
each
channel.
Before the fine
adjustment accordlng to E
5a the
playback
frequency response
should be checked.
E 1b
Aligning
the Frequency Response
of the Playback
Channels
-
the frequency response
sectlon of the test tape
is used
for
this
alignment.
It is recorded
at a level of
-20
db.
-
Check that
the
frequency response
of the
output voltage ls flat
and lf necessary
correct the high frequency
end
(
l0
-
L2kc/s
)
by
means
of the trlmmer
,'Entzer-
rung"
(Equallsatlon).
There is no
lnter-actlon between the trimmers
for the two
tape speeds.
After this
alignment, lt ls desirable to make
a
qulck
check
of
the
nolse
voltage at the
output of
the
playback
ampllfler with the machlne
runnlng but
without tape
and
with
the head
screen in
po-