Dual 1224 User manual

ition May 1974
Technical data
Current type
Line voltage
Drive Dual 1224
Drive Dual 1225
Power consumption
Current requirements
Dual 1224
Current requirements
Dual 1225
Platter
Platter speeds
Pitch control
Wow and flutter
Signal-to-noise ratio Dual 1224
Signal-to-noise ratio Dual 1225
Tonearm
Pick-up head
(cartridge holder)
Stylus pressure
Pick-up cartridge
Dimensions
Weight Dual 1224
Weight Dual 1225
Dual 1224
Dual 1225
Service Manual
AC 50 or 60 cycle, with appropriate motor pulleys
110/130 V and 220/240 V selector
Two-pole Dual single-phase asynchronous motor
Four-pole asynchronous motor
< 10 Watt
approx. 60 mA at 220 V 50Ocycle,
approx. 115 mA at 110 V 60 cycle
approx. 64 mA at 220 V 50 cycle,
approx. 115 mA at 110 V 60 cycle
1.45 kg, 270 mm @
33 1/3 and 45 rom, automatic tonearm setdown coupled to speed selector
Adjustment of approx. 1 semi-tone (6 %) at both platter speeds
<+ 0.15 % rated in accordance with DIN 45 507
Rumble signal-to-noise ratio > 55 dB
Rumble unweighted signal-to-noise ratio > 35dB in-accordance with DIN 45'500
Rumble signal-to-noise ratio > 56dB
Rumble unweighted signal-to-noise ratio > 37 dB in accordance with DIN 45 500
Torsionally-rigid tubular aluminium arm with vertical pivot mounting, horizontal self-adjusting
pivot mounting
Removable, suitable for acceptance of all (Dual 1224 all piezo electric) cartridges having 1/2”’
mounting and a deadweight of 2 — 10 grams (including mounting fixtures)
Continuously-adjustable from O — 8 p, reliable as from 1 p stylus pressure
See separate data sheet
329 x 274 mm (+ 2 mm tonearm overhang)
3.9 kg
4kg
Dual Gebriider Steidinger - 7742 St. Georgen!/Schwarzwald

Fig. 1 Pick-up Connection Diagram
right channel left channe!
a
1
Da 3
-——| > | re
i I t gfe = ———__-¢ q : |
1 s--s ee at a1 fiettos 7 ao
Lm oe Ss TR ~
| \
C1 | ! | '—~ Tonearm audio cable
The~ = —-471
° i
me 3 |
I
dl an a) with miniature plug 5-pin
| he +
; Q, rey Q9 3
Muting switch i ft
c oa | right channel
!
:
red
lead
| 1
| left channel
: | white lead
| |
| |
| | b) with phono plug
|
{
| i 1! TT]
{
! : ot
|
|
black
1
fl
white
L
ee
(red)
(yellow)
black
right channel left channel
red white
‘Mass right channel Mass left channe!
green blue
Qo
| en een ren eee
Mass sheet
Foto rey heres et ee a “”
oan ee ne a a 4
SSS oe
a a ae ae |
Contact plate at tonearm head ! Tonearm head
|
plug-in cartridge
|
| ep ef : Spring contacts between
| head and tonearm
t
red i white
|
(}
green | M, l blue
Cartridge Pa |
Record Q
SS inner side of groove 1 outer side of groove
left channel right channel

Contents
Technical Da
Pick-up Conn
Motor and Dr
ta
ection Diagram
ive
Pitch Control
Tonearm and
Replacing th
Replacemagnt
Tonearm Anti
Tonearm Guid
Tonearm lift
Start Cycle
Manual Start
Stop Switchi
Platter does not run when unit is plugged in and start
Switch operated
Platter does not reach required speed
Rumble in reproduction
Correct nominal speed obtained only at extreme settings
of pitch control
Suspension
e Complete Tonearm and Bearing Assembly
of Tonearm
-skating Device
Pick-up head not parallel to platter
e Mechanism
Tonearm misses edge of record
Tonearm strikes record during change cycle
Tonearm does not move onto record when drop cycle ist started
Tonearm lowers too quickly when drop cycle is started
Tonearm returns to rest immediately after being placed on
record manually |
Ng
Muting Switch
Record Drop
Shut-off and Change Cycle
Shut-off Mechanism
Spare Parts
Lubrication
Platter stops after automatic set-down of tonearm
The last record of a stack keeps repeating
After adjusting the tonearm set-down point for 7" records
the set-down point is not correct for 12" records
Record drops when unit is switched to "stop"
Records do not drop
Stylus slips out of playing groove
Vertical tonearm movement restricted during set-—down
Disturbing noises during change operation
No sound
Motor does not shut off
Acoustic feedback
with Exploded Views
ai
oa
owwo wo wo Oannt aan wm
10
10
11
17
4
12
AZ
12
13
13
13
14
14
14
14
14
14
15
21
20

Figve 2
1
Hida
ee
RRS EPR
AGEGOOOOL
CODD BGO
11 104 10 109 126 108 130 152
Fig. 3
Motor suspension and platter drive Dual
| AMMA MMEM Rs
oe
a
ad
1224
———
[| EE
ive a
1
‘Tl
ee 77,
tt
139 125 156
Motor suspension and platter drive Dual 7225
11 104 10 109 126 108 130 152
Motor and Drive
The platter and associated mechanism are
driven on the Dual 1224 by a two—pole asyn-
chronous motor (125) and on the Dual 1225
by a four-pole asynchronous motor (150).
Both motors have a rotor balanced at two
levels, polished bearing surfaces and en-
Sure vibrationfree running. In addition,
the four-pole motor is distinguished by
an extremely small stray magnetic field.
The speed of the motors is constant over a
supply voltage range of + 10 %. Deviations
in speed depend on, and are proportional
to, the line frequency. Adaptation of the
motor to 50 or 60 Hz power is accomplished
by changing the motor pulley (137/139).
Two-pole motor (Dual 1224):
Pulley for 50 Hz ATG, NOx. 292: 69:6
Pulley for 60 Hz Art. No. 2342897
Four=pole motor (Dual 1225):
Pulley for 50 Hz Art. No. 232 898
Pulley for 60 Hz Art. No. 232 899
137 150 156
The motor pulley is secured to the motor
shaft by a setscrew. When a pulley is re-
placed or exchanged it must be set at the
correct height (see Fig. 4).
The platter is driven by the idler wheel
(152) which is automatically disengaged
From the motor pulley when the unit is shut
off in order to protect its driving surface.
Platter speeds of 33 1/3 and 45 rpm are se-
lected by raising or lowering the idler
wheel (152) to the appropriate step on the
motor pulley.
When the selector lever (33) is moved, the
selector segment (108) rotates. This causes
the lever (130) fitted in the slot of the
selector segment to move in a vertical di-
rection. The idler wheel (152) mounted on
the swinging arm (155) is lifted off the
mator pulley and set down again on the mo-
tor pulley step for the appropriate speed.

Pitch Control
For platter speeds of 33 1/3 and 45 rpm
the unit incorporates a power-—independent
pitch control which permits a platter speed
variation of up to 6 & (approximately one
semi-tone).
When the pitch control knob (10) is turned,
the switch segment (108) and the switch
lever (130) attached to it are moved up or
down. This vertical displacement changes
the position of the idler wheel on whatever
step of the motor pulley it has been placed,
by the speed selector, and due to the ta-
pered shape of the pulley effects approxi-
mately + 3 % variation in speed.
Trouble Cause
Platter does not a) Current path to motor
run when unit is interrupted
plugged in and b) Idler wheel (152) not
start switch in contact with platt-
Operated er
es Motor pulley loose
Platter does not a) Motor pulley is not
reach required correct for local
speed line frequency
b) Slip between idler
wheel (152) and motor
pulley or platter
c) Excessive friction in
motor, idler wheel or
platter bearings
Rumble in re- Worn idler wheel
production
Idler wheel does not
contact motor pulley cor-
rectly
Correct nominal
speed obtained
only at extreme
settings of pitch
control
Fig. 5 Motor field connec—
tions (less voltage selector)
Coil II not in
2-pole motor
which, according
to model, can only
be used for 220 y
or 110 V or 150 ¥
Position of idler wheel
Fig. 4
Remedy
a) Check connection at switch plate and
voltage selector
b) Check switch lever assembly (130)
° Tighten motor pulley
a) Change motor pulley
b) Clean friction surfaces of idler wheel,
motor
pulley
and
turntable
platter.
If
necessary, replace idler wheel. Once
the drive surface of the platter has
been cleaned do not touch it with your
fingers
c) Clean and oil bearings
Replace idler wheel (152), clean platter
drive surface and motor pulley with grea-
seless solvent. (Once surfaces are cleaned
do not touch them with your fingers).
Adjust position of idler wheel by turning
adjustment screw (12) so that the fine
speed adjustment knob (10) is in the center
position by correct nominal (Fig. 4).
Fig. 6 Motor field connec-
tions (with voltage selector)
(ON pee GC | CSW eee
|

Tonearm and Tonearm Suspension
The tonearm of the Dual 1224 and 1225 is
counter balanced and pivot mounted verti-
cally and horizontally. This provides ex-
tremely favourable tracking characteristics.
The tonearm head is removable. To aid in
replacing or adjusting the tonearm head a
hole is provided in the chassis to facili-
tate adjustment of the tonearm head witheut
first removing the tonearm. Before setting
the correct stylus force for the cartridge
which has been installed the tonearm should
be balanced with the stylus force setting
at zero. It is recommended that balancing
should be carried out in the direct vici-
nity of the tonearm rest. This is carried
out by rotating the counterweight.
Fig. 7 Tonearm bearing assembly
Fig. 8 Tonearm bearing assembly
(view from underneath)
68
58
55
241
245
212
225
223
The counterweight is designed so that it
can balance cartridges weighing 1 -— 10 gq.
For shock absorption (absorption of brief
shocks) the counterweight is flexibly moun-
ted on the tonearm and secured to prevent
unintentaional rotation. The tonearm head
is designed to accept all cartridges with
internationally standard 1/2" mounting cen-
ters and weighing not more than 10 gq. Sty-
lus force is set by rotating the graduated
spring housing (ses and thus tensioning or
slackening the coil spring contained the-
rein. The scale is calibrated for an ad-
justment range of O - 5 p, permitting ac-
curate setting within that range in 0.5 p
steps.
Replacing the Complete Tonearm
and Bearing Assembly
To replace the complete tonearm and bearing
assembly we recommend proceeding as follous:
1. Tighten unit in repair jig, set stylus
force scale to zero and lock the tonearm
in position
2. Turn unit upside down, remove retainer
spring (188) and: unsolder tonearm leads
3. Remove main lever (223), disengage spring
(256)
4. Remove lock washer (227) and skating disc
(226), remove shut-off slide (225) from
eccentric pin on segment, ensure ball
(224) does not drop out
5. Slacken hexagon nuts (244), remove seg-
ment (245), then remove tonearm, ensu-
ring that bearing pivot (39) and compres-
sion spring (40) do not drop out.
Tonearm complete with bearing frame assem-
bly should be refitted in reverse order. The
unit is in normal position. Insert tonearm
complete with bearing frame assembly and
lock in rest. With tonearm held in place
turn unit upside down. Place segment (245)
in position and fit hexagon nuts.
Replacement of Tonearm
To remove the tonearm from the bearing fra-
me unsolder the tonearm leads and set the
tonearm tracking force scale to zero. Uns-~
creu locknut (65) with setscrew (64) and
bearing screw (68) (left-hand thread). Care-
fully remove tonearm from bearing frame.

Tonearm Anti—skating Device
The geommetrically caused skating force ac-
ting on any tonearm is eliminated to a lar-
ge extent in the case of the Dual 1224 and
1225 by means of a precision antiskating de-
vice.
The skating force is dependent on the tone-
arm geometry, on the stylus force and the
tip radius of the cartridge stylus. The in-
ward pull of the tonearm caused by the
skating effect leads not only to undesirab-
le jumping of the tonearm when set down on
the record but also unequal forces on the
two opposite groove walls with resultant
unfavourable effects. These can be correc=
ted with the aid of a suitable anti-skating
device. By turning the knob (69) of the an-
ti-skating device located on the cover the
asymmetrical plate cam (238) is moved. This
plate cam has tuo different curvatures which,
according to the different scales used, for
spherical and elliptical tip styli and for
CD 4 pick-up cartridges, move the skating
lever (241) out of its position of rest and
transmit the counter force to the tonearm
by means of the tension spring (256).
Skating adjustment is set at the works for
conical styli with a tip radius of 15 +
2 um and for elliptical styli with measure
ments of 5/6 and 18/22 um and also for CD 4
cartridges. The hexagon nut (239) is firmly
tightened and locked with paint. Readjust-
ment should only be attempted with the aid
of the Dual Skate-O-Meter and the L 096
test record. This is best done by an autho-
rised Dual service station.
Trouble
Tonearm head not located parallel to plat-
ter
Cause
Shocks incurred during transport have alte-
red the location of the tonearm head on the
tonearm tube
Remedy
Remove platter, slacken the screw on the
tonearm head with the aid of a screwdriver
inserted through the hole in the chassis
provided for this purpose. Retighten screw
after aligning the tonearm head (Fig. 10).
Fig. 9 Anti-skating force
a) Anti-skating force O-set-
ting. No compensation
of the skating force ta-
kes place as a result of
the action of the tension
spring at the fulcrum of
the tonearm.
Anti-skating mechanism
set to “’1.5”’ on the scale
for elliptical styli. Tone-
arm on tonearm rest.
The tension spring pro-
duces the anti-skating
force which is transmit-
ted to the tonearm via
the segment, The V-spring
presses the skating lever
against the plate cam.
b
—
c) As “b” but tonearm abo-
ve platter.

Fig. 17 Tonearm guide mechanism
199 173 132 A 193 180 223 202 212 245
Tonearm
Lift
(Cue
Control)
The
tonearm
lift
permits
the
tonearm
to
be
set
down
on
the
record
safely
at
any
desi-
Ted
point
outside
the
shut-off
area,
Moving
the
tonearm
lift
handle
(44)
for-
ward
causes
lift
cam
(235)
to
rotate.
This
movement
is
transmitted
via
positioning
slide
(212)
to
the
lift
pin
which
then
ralses
the
tonearm.
Fig.
12
Tonearm
lift
(tonearm
raised)
44 235 236 212
Tonearm Guide Mechanism
A guide groove located on the underside of
the main cam (193) controls the automatic
lift and set-douwn of the tonearm as the
cam rotates through 360. Tonearm lift and
lowering are controlled by main lever (223)
and lift screw (249). Horizontal movements
are controlled by the main lever (223) and
the segment (240).
Automatic tonearm set-down is designed for
12", and 7" records and is coupled to the
platter speed selector. Set-—down points
are determined by the spring pin of seg-
ment (240) contacting the positioning slide
ee which is. only raised by the main lever
223) during the change cycle and thus mo-
ves within reach of the spring pin fitted
on the segment. On completion of set—down
or change cycle (tonearm sets down on the
record) the positioning slide (212) is
released again and returns to its normal
position. It thus moves out of reach of
the spring pin permitting the tonearm to
move horizontally without hindrance while
playing the record.
After moving the tonearm (by hand) to the
desired spot on the record the tonearm lift
handle is tapped lightly (to the rear) to
release the mechanism.
The positioning slide (212) is thus relea-
sed and the tonearm descends slowly, con-
trolled by the viscosity damped lift pin.
The height of the stylus above the record
can be varied from zero to 6 mm by turning
adjuster screw (43). Turning to the right
increases the height, turning to the left
reduces the height.
251 43 249 245

Trouble
Tonearm misses edge
of record
Tonearm strikes re~,
cord during change
cycle
Tonearm does not
move onto record
when drop cycle is
started
Tonearm lowers too
guickly when drop
cycle is started
Tonearm returns to
rest immediately af-
ter being placed on
record manually
Start Cycle
Cause
a) Record setting
incorrect
b) Set-down point
incorrectly
adjusted
c) Record not stan-
dard size
d) Friction surfaces
of tonearm clutch
dirty
Tonearm height ad-
justment incorrectly
set
Excessive damping
caused by dirt in si-
licone oil in lift
tube
Insufficient damping
caused by improper
addition of lubricant
to damping compound
Shut-off mechanism
has shifted out of
position during
shipping
Moving
the
start
switch
(33)
causes
change
lever
(209)
to
rotate
outwards.
This
ini-—
tiates
the
following
functions:
a)
A
lug
rotates
shift
arm
(180).
The
lat-
ter
in
turn
by
means
of
a
tension
spring
moves
the
change
lever
(130)
and
thus
the
idler
wheel
(152)
into
engagement
with
motor
pulley
(137/139)
and
platter
ye
At
the
same
time
the
power
switch
167) is actuated by the switch slide
(177) coupled to the shift arm and the
platter starts to rotate.
b)
Change
lever
(209)
is
brought
within
reach
of
the
cam
follower
lever
(195)
so
that
the
latter
is
pushed
into
the
chan-
g&@
position
after
subsequent
rotation
of
the
main
cam.
.
Remedy
a) Carry out necessary adjustment by means
of right-hand selector lever (33).
b) Set right-hand selector lever to "45".
- With a screwdriver inserted through the
hole exposed turn eccentric pin until
the tonearm sets down approximately
1.5 mm from the edge of the record. (Ad-
justment is only carried out for 7" re-
cords and is then automatically correct
for 12" records.)
c) Use standard record
d) Clean clutch surfaces
Adjust arm height with adjuster sleeve (38).
Height is correct when stylus tip is 2 = 3 mm
above selector lever (33) when arm is remo-
ved from rest.
Remove tonearm complete with bearing assem-
bly (described on page 6). Remove lock was-
her (37), detach adjuster sleeve and remove
second lock washer 137). Remove lock washer
(253) on adjuster lever (214). Detach posi-
tioning slide from pin on adjuster lever,
turn slightly until lift pin (249) is relea-
sed. Remove lift pin. Clean lift tube and
lift pin. Smear lift pin evenly with "Wacker
Silicone oil AK 500 OOO". Smear lift pin
evenly with "Wacker silicone oil AK 500 O00".
Reassemble components,
Remove tonearm complete with bearing assembly
(described on page 6). Remove lock washer
(37), detach adjuster sleever and remove se-
cond lock washer (37). Remove lock washer
(253) on adjuster lever (214). Detach posi-
tioning slide from pin on adjuster lever,
turn slightly until lift pin (249) is rele-
ased. Remove lift pin. Clean lift tube and
lift pin. Smear lift pin evenly with "Wacker
Silicone oil AK 500 O00". Reassemble com-
ponents.
Before using changer after moving, run it
through start cycle with tonearm locked
on rest (selector moved to "start")
|
225 223 193 212 180 209 183 214 157

|
i
193 180 212 209 183 214 157
Fig. 15 Muting Switch
Cam wheel at zero:
Contacts of muting switch opened
Cam wheel is turning:
Contacts of muting switch is closed
10
Moving the operating switch (33) also re-
leases the start level (208) which is pul-
led towards the main cam by means of ten-
sion spring (207). By this means the shut-
off lever 7190) is moved within the range
of the dog on the platter pinion thus dri-
ving the main cam. The change lever (209)
is also locked. To prevent malfunctions the
operating switch is locked in position du-
ring the start cycle (rotation of the main
aay Just before the main cam Teaches neu-
tral position (at the end of the change cy-
cle) the start lever is pushed clear by the
main cam and thus the operating switch and
change lever are returned to their original
positions. After installation and after mo-
ving the changer the unit should be started
with the tonearm locked on the rest. This
will automatically readjust the shut-off
lever which may have shifted out of posi-
Lions
Manual Start
When the tonearm is swung inwards by hand
the pawl (202) on the shift arm (180) en-
Gages on a square end pin fitted in the
chassis, retaining the shift arm in this
position and thus the idler wheel (152)
in engagement with the platter.
The slide (177) linked to the shift arm
actuates the power switch and sets the plat-—
ter in motion.
On reaching the run-out groove the tonearm
automatically returns to its rest position
and the unit shuts itself off. If, however,
the tonearm is lifted off the record before
completion of play and returned to the rest,
the pin of segment (245) releases the paul
(202). The tension spring then returns the
shift arm to its initial position, opening
the power switch and disengaging the idler
wheel.
Stop Switching
When the operating lever is moved to "stop"
only the starting lever (208) is drawn for-
ward. As a result, the shut-off linkage en-
gages with the main cam. The cam follower
lever remains in stop position. When the
tonearm is on its rest and the operating le-
ver is pushed to "stop", the change lever
must not jam.