Dual 502 - Tonearm Assembly Procedures; Tonearm Removal from Frame; Tonearm Assembly Removal; Spring Housing Replacement

(4,
•
Secure unit in repair
jig. Remove weight
(50).
Unscrew
straining screw
(54) and
set
tracking
Farce to zero
(65).
2.
Move unit into
head
position. Remove
screening
plate.
Unsolder tonearm
leads
an the
connecting
plate (142).
3. With
the unit in
normal
position
screw
the
two mounting
screws SW
4.5 - (57)
counterclockwise to the
stop in
the 'frame
(55).
Attention!
Observe bayonet
slide
mounting.
Slide
tonearm
rearwards and
re-
move
lt from
the bearing
frame
(55).
When
reinstalling the tonearm proceed in
reverse order.
Removal of tonearm assembly
with tonearm bearing
Proceed as
follows:
1.
Tormarrin and
lbinearnn
Bearing
The Dual 502
has a light, torsion resistent
all-metal tonearm which is suspended in a
gimbal. Suspension is by
means of 4 hardened
and precision polished steel points which
rest in precision ball bearings. Tonearm
bearing friction
is thus reduced to a mini-
MUM
Bearing friction:
vertical
Bearing
friction:
horizontal
▪ 0.07 mN (0.007 p)
▪ 0.16
mN (0.016 p)
related to stylus point.
As a result, lt ensures extremely favorable
pick -up
conditions. Before adjusting the
tracking force to suit the built-in pick -up
cartridge the tonearm
should be balanced
with the scale set to 0. Coarse adjustment
is carried out by moving the stem
(50), the
subsequent fine adjustment by turning the
counterweight is designed so that pick -up
cartridges with a deadweight (incl.
hardwa-
re) of 4.5 to 10 g can be balanced. The
tracking force is adjusted by turning the
coil spring mounted in the spring housing
(65). The spring housing is provided with a
scale with markings (0 - 30 mN/0 - 3 p)
which allow precise
setting of tracking
Far-
ce. One division corresponds to 1 mN (0.1 p)
within the range of 0.2 - 1.5 p, and 2.5 mN
(0.25 p) within
the range of 15 to 30 mN
(1.5 - 3 p).
Removal of tonearm from bearing frame
1.
Secure unit in
repair jig. Set
tracking
force scale (65).
2. Move
unit into head
position.
Remove
screening plate (144).
Unsolder tonearm
leads
(142) an connecting plate (142).
3. Disengage compression
spring (199) an
bearing frame (yoke)
(198). Turn bearing
section (177) by 90
0
and
remove it. Re-
move the setting bar (176).
4. Disengage
tension
fety
washer (192)
ver (191).
spring
(185), undo
sa-
and
remove
skating le-
5. Remove
safety washer (189) and sliding
washer
(188). Also remove shut-off bar
(160) from segment (184).
Fig. 5
Tonearm
bearing
46
61
60
55
64
180
187
45
44
65
67
47
184
6. Undo hex
nuts (187). Also
remove segment
(184).
7. Undo hex nut (180).
Remove tonearm com-
plete with bearing.
When attaching the tonearm proceed in rever-
se order. However, lt should be properly ad-
justed when mounting the segment (184).
(Refer to page 7 ).
Replacement of spring housing
Remove tonearm (49) from bearing frame as
described above. Loosen lock nut
and thread
pin (44). Unscrew bearing screw (67).
Observe left-handed thread!
Lift bearing frame (55).
Remove disk and
spring housing (65).
When installing the
spring housing make sure that the helical
spring catches the
recess of bearing frame
(55). Slide in washer (66).
Tighten bearing
screw (67). Reinstall
tonearm (49). Using
threaded pin (44) and lock nut
(45) adjust
bearing
play as described below.
Fig. 6
Tonearm bearing
(bottom
view)
64
54
50
191
187
184
176
160
5