Dual 1215S - Anti-skating Adjustment; Anti-skating mechanism description

Anti-skating adjustment
The tendency of a
tonearm with an offset (angled)
head to
"skate"
inward across
the
record is
eliminated
in the
Dual
1215 S by
a
preci-
sion anti-skating mechanism.
Skating force
depends on tonearm geometry, stylus
force and the
tip
radius of the stylus. The inward
pull on the tonearm caused
by the skating effect
gives rise not only to an
undesireable jum-
ping of the tonearm when it is.set
down on the record, but also to
unequal forces on
the two opposite groove walls, with
correspon-
ding iii
effects. This can be corrected with
proper anti-skating
adjustment.
By
turning the anit-skating adjustment knob
(59) on
the chassis,
an
asymmetrical curved
washer (249)
is turned. This
washer has
two different
curved surfaces
corresponding,
respectively• , to the
red and
black scales on the anti-skating
dial. The red
scale
is
for
conical
(spherical-tip)
styli; the bleck
for elliptical
(bi -radial) sty-
li. When the knob is
turned, the curved surfaces
push the anti-
skating lever
(231) away from its rest
Position so that is applies
a suitable counterforce via a spring
(233).
Skating compensation is
set at the factory for
conical styli with
a tip radius of 0.6 to 0.7 mil (.0006 - .0007
inch), and
for ellipti-
cal styli with
measurements of
0.20 to 0.23
mil by
0.79 to 0.87
mil. The
hex adjusting nut is tightened and
sealed. Readjustments
should be attempted only with
the help of the Dual
Skate-O-meter
and test record L 096.
This work is best done by an
authorized
Dual service agency.
Symptom
Fig. 9
Anti-skating
a) Anti-skatind in „0"
b)
Anti-skating
mechanisrn in
on the
scale for
conical styli.
Tonearrn on
rest position
c) See "ra .. . tonearm
only over turntable
Cause
Remecty
Cam wheel
Shietd
ensron
sPring
ihieW e \
/
&Ab
Shut
-off
Radius for
conrcal styli
Radius
Anti-skating f
Skating
force
Anti-skating
rnechanism
elligatrcal
Stylus sk
ips
a) Tonearm not balanced
a)
Balance tonearm according
to operating
instructions
b)
Stylus force too
low b) Set stylus force to
cartridge manufacturer's recommen-
ded value
c) Stylus worn or
chipped c) Replace stylus
d) Excenssive
friction in
d) Check tonearm
horizontal pivot. Should have
barely
tonearm bearing noticeable
play. Adjust vertical bearing
only with the
left bearing screw (44)
and the horizontal bearing
with
nut. Horizontal
bearing is correctly adjusted
when the
tonearm, with
anti-skating 0.5 p,swings freely
from •
center
to rest
e) Ball (235)
missing from
shut-off e)
Replace ball (235)
raul
f) Anti-skating
wrongly
adjusted
f) Correct
antiskating setting
Tonearm sets
down beside tonearm Arm segment (246) incorrectly ad-
Correct
segment positioning: after
loosening
nut
(247)
rest
justed
rotate
segment (246) .
When
lbosening
adjusting nut
(245), hold parts
firmly.
Adjustment is
correct when
the
tonearm
descends to
the tonearm
rest
without bin -
ding.
After
adjustment,
check bearing
friction
• Horizontal pivot
friction too high
Tonearm is set too high on tone -
arm lift. Main
lever jams against
guide pin of lift screw assembly
Stylus
should be no farther from
record surface than 1/4".
Adjust by turning
screw (211)
7