Dual 522 - Stroboscope and Pitch Control; Stroboscope Usage; Pitch Control Adjustment; Tone Arm Bearings

Fig. 6
Fig. 7
109
103
45
200
18 2
113
111
114
116
Stroboscope
Even
during the play
mode the
stroboscope can be
used to check
the
accuracy of the
turntable speed
adjustment to 33
1/3 and
45
rpm.
Accurate
adjustment is
manifested by seemingly
motionless bar
marks of the
stroboscope. If
the marks run
in the same
direction
as the
turntable, the speed
is too high
and vice versa.
To vary
the
adjustment,operate the
"pitch" knob 18. The
strobo
marks on the
turntable
rim, have the
following
meanings (starting
from
the
lowest
row): 33 1/3 rpm at 60
Hz, 33 1/3
rpm at 50 Hz.
To exchange
the glow lamp
GI 131,
remove the
screws 234
and the
strobo case.
Pitch
Control
This feature
is
independent of the
power and
controls both turn-
table
speed. The
tuning range is
max. 6 % or
about one
semi-
note.
When
you
rotate the
knob 18, you will move the belt pulley 2
105.
This motion will
be transferred
by the toothed
belt 109
to the
belt pulley 1
113. As a
result, the counter
bearing 114 and
taper
sleeve of motor
pulley 116
are shifted
upwards or down-
wards,
respectively.
The taper
sleeve of the
motor pulley
116
causes the
pulley
diameter to be
reduced or
increased, which
permits the
variation of
the rated
speed within
the said
range of
±
3 %.
Tone Arm with Bearings
The I ight-weight
torsion-resistant
aluminum-tube tone arm has a
62
universal
gimbal bearing
characterized by four
hardened and
lapped steel points
located in high-precision
ball bearings. The
tone -arm
bearing
friction is thus reduced to
a
minimum,
namely
less than 0,07 mN 0r0,007 gr in vertical and
less than 0,15 mN or 0,015 gr in horizontal
direction,
referred to the stylus po int.
This ensures
particuiarly satisfactory tracking
conditions. Before
adjusting
the tracking force,which
should comply with the pick -
67
up system used,
adjust the tone arm to its
balanced position while
the
tracking-force scale indicates zero.
The tracking
force is produced by tensioning the
helical spring
located in
the spring case 62. The rotary turn
knob 60 has a scale
201
with marks permitting exact adjustment of the tracking force
within the range 0-30 mN lor 0—
3 gr).
Z LI- N
209
202
60
To Remove the
tonearm complete with the
tonearm bearing
We
recommend the
following
procedure:
1. Secure the
unit in a repair stand.
Turn the rotary turn
switch
60 to the
zero position. Lock the
tonearm 38. Remove
the
counter-weight 55.
2.
Adjust record player to head
position. Remove the shield
160.
38
Unsolder the tone -arm leads from
muting switch.
3. Remove the main lever
177. Remove the lock
washer 242.
Rotate the set screw 26
until guide bearing
241 and setting
ting
bar 228 come free. Remove
lock washer 228 and
setting
bar
204.
4.
Unlock the tension
spring 212,
loosen the lock
washer 216 and
remove
skating lever 215.
5. Remove lock washer 202 from segment
200.
6.
Remove hex. nuts 209 and
the screw 202. Remove
the bearing
200
201 and the
segment 200.
7. Grip the frame 44 and the
tonearm 38. Loosen the machine
screw 45 and take off
the tonearm and frame.
Reassembly of the tonearm
involves the reverse procedure. Take
care that the grub screw 43
is correctly seated in the
bearing when
when fastening the frame 44.
4