Sony ST-5066 - Page 9

=.
v'-
Y
v
Procedure:
l. With
the equipment
connected
as
shown in Fig.
3-5,
set
the
signal-generator
controls
as
follows:
Frequency
.
.
Specified frequency
of
ceramic
filter.
See Tabte
3-
l.
Modulation
..
.
Fm,400Hz,75kHz
deviation
(
100%)
Output level
.
.
1,000rrV
(60
dB)
2.
Set
the
tuner
switches
as
f«rllows:
FUNCTION
switch
F-M
MODEswitch..
...
MONO
3.
Adjust
the
signal
generator
frequency
slightly
to
obtain
a ntaximum
output,
then change
the
signal
generator
modulation
to
a-m, 4OOHz
3Wo.
4. If
the discriminator
transformer
IFT2OI
is not
aligned
correctly,
400 Hz
ripple
will
be obseryed
as
shown
in Fig.
3-6.
I
5.
Turn
the
secondary
side core
of
discriminator
transformer
IFT20l
(see
Fig.
3- I
0) to
obtain
a minimum
indication
on
the oscilloscope
with an
alignment
tool
as
shown in Fig.
3-6.
Fig.
3-6. Fm
discriminator
alignment
output response
Note:
Turn
the
core
carefully
and slowly
because
the output
appearing on
the
oscilloscope
jumps
up
and down
when
turning
the
core. This
might
cause
difÍï-
culty
in
determining
the
point
of
mini.
mum
output.
Also,
at both extreme
positions
of
the
top
coÍe,
decreased
out-
put
will
be observed.
The real null
point
should
be obtained
in
the middle
of the
core
thread
length,
and
mar<imum output
appeaÍs
at
each side
of
the true null
point.
6.
Change
the
signal
generator
modulation
to
fm,
400
Hz,
I5 kHz
deviation
(
100%).
7
.
Turn
the core
of
fm
IFTI
0l
and the
primary
side
core
of
discriminator
transformer
IFT201
(see
Fig.
3-10)
to obtain the maximum
output.
3.2. FM
FREOUENCY
COVERAGE AND
TRACKING
ALIGNMENT
Note:
Before
startirrg
this
alignment,
the
fm
i-f
and
discriminator
alignment
should
be
performed.
Test Equipment
Required
l.
Fm
signal
generator
2.
Ac VTVM
3. Oscilloscope
4.
Alignment
tools
Preparation:
l. Connect
the equipment
as
shown
in Fig.
3-'l
.
2. Set
the
tuner
switches
as
follows:
FUNCTION
switch
FM
MODEswitch......MONO
Signal Generator
Method
Follow
the
procedures
given
in Table
3-2
when
performing
this
alignment with
an
fm
signal
generator.
Be
sure that
the dial is mechanically
calibrated.
Off-theAir
Signal Method
F'requency
coverage
and
tracking alignment
can
also
be
performed
by
utilizing off-the-air
local
fm
signals. However, before
performing
the alignment,
be
sure
that the
dial
is
mechanically
calibrated.
Adjust
+
t
h
Fig.3-5.
Fm
Í-f
and
discriminator alignment
fesf
setup
by
rf signal
generator
oscilloscope
ac
VTVM
0.O2ttF
sT-5066
0.02ttF
rf
signal
generator
r-
:J
V
7