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Dyna FM-3 - Front End Alignment Process

Dyna FM-3
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14 ( >
Unsolder
and
lift off
the
jumper
wire which con-
nects
from
eyelet
# 23 on
PC-8
to
eyelet
B.
15 (
v)
Temporarily
solder a wire from
eyelet
# 23 to eye-
let
# 32
on
PC-8.
16(
vi
Adjust
the
bottom
slug of
T5
for
maximum
closing
of
the
eye.
17
(,v)
Unsolder
the
end
of
the
temporary
wire from
eyelet
#32
and
temporarily
connect
it
to
eyelet
#31.
18(
/)
Solder
a 2" piece of
bare
wire to
the
center
ground
pin
of socket V7,
19(
v)
Tum
the
top
slug
of
T5
in (clockwise) 4 to 5
turns,
which brings
it
close
to
the
proper
adjustment
point,
20(
V)
Touch
the
free
end
of
the
wire from
the
center
ground
pin
of V7 to
eyelet
#31.
You
will observe
that
there
is a deflection of
the
eye
(either
inward
or
outward),
Rotate
the
top slug of the
discriminator
transformer
T5
back
and
forth slowly while alter-
nately
touching
and
releasing
the
free
end
of
the
wire
from
the
center
ground
pin
of
V7
to
eyelet
#31.
The
actual
adjustment
of
the
slug
must
be
made
while
the
wire is not
touching
the
eyelet.
Check
the
eye's
deflection
after
each
change.
You
are
seeking
the
pre-
cise
point
where
there
is no shift
in
the tuning
eye
as
the
wire is
touched
to,
and
removed from,
eyelet
#31.
There
may
be
slight
changes
in
the
brightness
of
the
eye
as
this
is
done,
but
these
are
of
no
con-
sequence,
Tum
the
slug
in
the
direction which mini-
mizes
the
shift
in deflection
until
there
is
no
shift
when
the
wire
makes
or
breaks
contact
with
eyelet
#31.
21
(j
Remove
the
temporary
wire between
eyelets
# 23
and
#31.
22 (
!)
Re-connect
the
jumper
wire from
eyelet
#23
to
eyelet
B.
Keep
it
reasonably
close to
the
board.
23 ( J)
Remove
the
wire from
the
center
ground
pin
of
socket V7.
24 ( )
THIS
STEP
REPLACES
STEPS
14
THROUGH
23
WHEN
A
VTVM
IS
USED
FOR
DISCRIMINATOR
ALIGNMENT.
IF
YOU
ARE
NOT
USING
A
VTVM
AND
HAVE
COMPLETED
STEPS
14
THROUGH
23,
PASS
TO
STEP
25
NOW.
Switch
the
VTVM
to
-DC
and
set
it
for a
range
of
about
10 volts full scale.
Connect
the
COMMON
lead
to
the
tuner
chassis,
and
the
DC
probe
to
eyelet
#32.
Adjust
the
bottom
slug of
T5
for
the
maximum
meter
reading
(about
-11
volts).
Switch
the
VTVM
to
its
most
sensitive scale.
While
shorting
its
leads
together, reset its zero
adjustment
to
bring
the
meter
needle to a specific
point
near
mid-scale which
can
serve
as
a new zero,
or
to
a
center-scale zero if
one
has
been
printed
on
your
meter
scale.
Connect
the
COMMON
lead to
the
chas-
sis
again,
but
connect
the
DC
probe
to
eyelet
#31
this
time.
Tum
the
top
slug
of
T5
in
(clockwise)
4 to 5
turns
as
a first
approximation,
and
then
care-
fully
adjust
it
until
the
meter
reads
exactly
zero.
To
do
this
conectly,
it
is essential
that
you
go
through zero first,
and
then
back
up
to
locate
it
precisely.
18
25( ,j
Cut
a
one
inch
piece of wire
and
strip
114"
of insu-
lation
from
one
end.
The
other
end
need
not
be
stripped.
Insert
the
stripped
end
into
the
bottom
of
eyelet
#29
(S).
'rhis
wire
should
stand
up
straight
from
the
PC-8
board
with
the
other
end
free,
and
adjacent
wires
should
be positioned
away
from it.
This
wire
should
be
cut
off so
that
it
stands
up-
right
to
a
height
of
IJAa"
above
the
PC-8
board.
This
wire
may
seem to be
unusual,
as
it
is con-
nected
at
one
end
only. However,
it
is
what
is known
in electronic
parlance
as
a
"gimmick"
and
it
is
actu-
ally
a small
value
capacitor
which corrects for
the
effects of
interaction
between
the
adjustments
of
the
two slugs
in
the
discriminator
transformer.
At
such
times
as
realignment is performed, this
"gim-
mick"
should
be
removed
before aligning the dis-
criminator.
Alignment
of
the
Front
End
If
you
wish,
the
bottom
plate
can
be
installed
during
alignment
of
the
front
end.
In
this
section,
dial
tracking
will
be
simplified if
another
FM
radio
is
available
to
enable
you
to
identify
stations
readily.
Make
sure
capacitor
C9
is vertical, for
if
it
is
tilted
toward
C8,
dial
tracking
will
be affected.
26
(v5
Tum
the
tuning
knob
until
you
have
located
an
FM
station
of known frequency
at
the
high
end
of
the
band
(close
to
108
megacycles),
the
higher
the
better.
27( )
Adjust
the
oscillator
trimmer
capacitor
C8
using a
small screwdriver.
At
the
same
time
readjust
the
tuning
knob
until
the
station's
frequency
is
indi-
cated
in
the
plastic
window
by
the
tuning
dial.
In
other
words,
you
set
the
dial
to
show
the
correct
frequency
and
adjust
the
trimmer
capacitor
until
J
the
eye
closes
to
a
maximum.
28(
)
Now
find a
station
of known frequency
at
the
low-
est
end
of
the
dial (close to
88
megacycles).
Using
a
s_mall
screwdriver,
and
touching
only
the insulated
handle,
adjust
the
brass
slug
in
the
oscillator
coil
LA
while
setting
the
tuning
dial
to
the
station's
broadcast
frequency.
This
is
the
same
type
of
ad-
justment
as
was
made
in
the
preceding
step.
It
may
be necessary
to
repeat
the
adjustments
at
the
two
extremes of
the
dial several times to
have
the
tuner
"track"
properly.
If
the
adjustments
are
not
made
accurately,
the
dial
readings
will
not
coincide
with
station
frequencies
across
the
dial.
Correctly
following
this
procedure
should
enable
dial
tracking
which is
accurate
to
within
7f;
division
(±O.2
megacycles).
I
29
(J
)
Tune
accurately
to
a
station
near
108 megacycles
and
adjust
the
two
trimmer
capacitors
CI-B
and
CI-D on
the
top
of
the
tuning
capacitor.
The
screw-
driver
should
not touch the capacitor shield
when
making
these
adjustments.
The
adjustment
should
be
made
for
maximum
eye
closing.
If
the
eye
is
closed to its
normal
maximum,
the
effects
of
these
adjustments
will
not
be
readily
apparent,
so
it
is
essential
that
a weak signal be
used
here
(where
the
eye
is
about
%"
open)
or
proper
alignment
will
not
be
realized.

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