If either end
of the armature
strikes
the pole
piece a
very
disagreeable rattle
will
result. To correct
a
misalignment
of the
armature
a pair of spacer tools, shown
in
Figure
3, and a screwdriver
will
be necessary.
These
spacer tools should be
made
of .010
phosphor
bronze
stock aborit
1/8
inch
wide.
The
distance between
the open
ends of
the tool should he
.091
inches.
See
Figure 3a.
Any loose
screws, nuts
or parts in
the speaker
may cause rattles and
for that reason
in making
adjustments
all screws should
be seated properly,
which means that all screws
and
nuts should
be drawn
up
firmly
enough to prevent their loosening
when
the speaker
is
placed
in
operation.
Care should
be
taken to prevent stripping
of the threads on the
screws and nuts
as well as to prevent
torsion
of the elements held in place
by such
screws
and nuts.
To readjust
the
armature it will
be
first necessary
to
free
it. Figures 4 and 5
show
the method
of
doing
this. The screws
shown as "C" should be
backed
off
about
two
turns. Do not remove
them entirely.
When the two screws
are loosened it is a simple
matter
to insert one of
the spacer
tools between
each
of
the two armature
ends and the pole pieces as
shown in Figures
6
and
7.
When the
spacing
tools are inserted
the clearance
between the armature
and
the
pole pieces must necessarily
be the
required ten thousandths as this is
the thickness
of
the
blades of the
two spacers.
After
the spacer tools
have
been
inserted,
one at each end, the two screws
"C"
that
were
loosened
(Figures 4 and 5) should be tightened firmly. Figure 8 shows the
method
of
tightening
the upper screw
with
the
spacers in
place.
After the two screws have been tightened
the
spacer
tools
should be removed
and the
Loudspeaker tested.
If the rattle has been eliminated
no
further
adjustment
will
be necessary. If,
however,
the rattle is still present
it may
be due
to
the
fact
that the
cone
is out of
centre with
respect to
the
connecting rod.
To
correct
this, again refer
to Figure 2.
The
screw
"d"
holds the
thrust
lever.
When
this screw is loosened the
cone will automatically assume the proper
position
and
the
screw
"d" should
then be tightened
down. Care
should be taken that the
sides
of the
thrust lever,
visible
in
Figure
2,
be
held at right angles to the
pole
pieces
as
shown
when
tightening "d".
The Loudspeaker
should again be tested. If the rattle still persists it
is
probably
due
to an
excessive
pressure on the connecting
rod
which may
be
corrected as shown
in Figure
9. A soldering iron should
be
applied
to the point
where
the
inner end
of
the
stylus
is
soldered
to the thrust lever.
The solder at that point should
be
softened
sufficiently
to
allow free
movement of
the stylus. Here again the adjustment
is
automatic
and
it is
only
necessary to keep the solder soft until this readjustment takes place.
PART II
Should it become
necessary to replace the
field coils
due
to burn -out
or
other
causes,
it will be
necessary
to remove the
entire
reproducer
unit.
The procedure is as
follows:
1. Remove the
flexible
leads
of the
coils from the
binding
posts.
Tag the leads
as
they
are
removed so that
when
the
unit
is reassembled they may
be
connected
to the
proper binding
posts. THIS
IS IMPORTANT.
2. Remove
the small nut
holding
the
cone
to the connecting
rod
shown
in
Figure 1.
5
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