Dual 521 Service Manual

Table of Contents
Page
3
Specif ication
4
Motor and drive
4
Speed
selection
4 Turntable
4
Belt
4
To replace the
motor pulley
5 Stroboscope
5 Tuning to the pitch-of-tone level
6
To replace the
spring case
6
To adjust
the tone arm
bearings
6
Tone arm with bearings
6
To remove the
tone arm from
its bearing
frame
6
To
remove tone arm
complete with
bearings
6
Anti-skating device
7
Tone arm lift
7
To replace the lift
plate
7
Tone arm control
8
The starting sequence
8
Manual start
8
Continuous play
8
Muting switch
8
Final shutting-off
9
Stop circuit
9
Adjustments
9 Tone arm
set-down point
9
Set -down point
for 30 -cm
records
9
Set
-down point for
17 -cm
records
9
Shut-off
point
9
Tone arm l ift
height
9
Troubleshooting
9
Turntable does
not start
9 Turntable
speed
unsatisfactory
10
Tone arm
improperly lowered
10 Acoustic
feedback
10 Rated speed
borders
pitch adjustment
range
10 List of spare parts ( I
nstructions)
12
Explosivie views
14 Lubrication
Specification
Mains frequency
50 or 60 Hz; use associated motor pulley
Maind voltage
110 — 130 V or 220 — 240 V, pluggable
Drive motor
Dual model, 8 -pole, synchronous
Drive
by motor pulley-to-turntable belt
Power consumption
10
watts approx.
Current drain
75 mA at 220
volts, 50 Hz; 140 mA at 117 V 60 Hz
Turntable
non-magnetic, dia. 304 mm,
vveight 1.2 kg
Record speeds
33 1/3
and 45 revolutions per
minute
(rpm)
Tone arm lift
automatic, coupled to
speed selection
Pitch of tone
adj. range about 1 semitone (6 %) ,
both speeds
Wow and flutter
less than ± 0.1 % by
test standard
Signal/noise
ratio
instrinsic min. 60 dB, external min. 40 dB
Tone arm
tubular
anti-torsion metal tube
Tone arm bearings
universal four-point gimbal
suspension
TA brg. friction
vertical less than 0.10 mN ref. to
stylus point
horizontal less than 0.40 mN
ref. to stylus point
Tracking
force
continuously
adjustable in the range
0—
50 mN
(0—
5 gr);
reliable operation
with 5 mN
(0,5 gr) and higher
Pickup
head
detachable, accpets
all Dual snap-in cartridges and all
other 1/2" systems
weighing between 4.5
gr and 10 gr, mounting material
included
Weight
4.1 kg
For dimensions and bench
cutout, refer to Installation I nstructions.

Dual 521 Specifications

General

Drive System	Belt drive
Speeds	33 1/3 and 45 RPM
Weight	5.5 kg
Anti-Skate	Yes
Stylus	Elliptical
Output	Depends on cartridge