Dual 1226 - Pitch Control

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 varia-
tion of up to 6 % (approximately one semi-
tone).
When the pitch control knob (13) is turned,
the suitch segment (108) and the switch le-
ver (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
run when unit is motor interrupted
plugged in and b) Idler wheel (150)
start switch opera- not in contact
ted with platter
c) Motor pulley
loose
Platter does not a) Motor pulley is
reach required not correct for
speed local line fre-
quency
b) Slip between id-
ler wheel (150)
and motor pulley
(113) or platter
c) Excessive fric-
tion in motor,
idler wheel or
platter bearings
Rumble in repro- Worn idler wheel
duction
Idler wheel does not
contact motor pulley
correctly
Correct nominal
speed obtained
only at extreme
settings of pitch
control
Trouble
Tonearm head is not parallel to turntable
platter.
Cause
Orientation of tonearm head on tonearm tu-
be has altered because of jolting in trans-—
port (shipping).
Remedy
Remove turntable platter with the help of
a screwdriver inserted through the hole
in the chassis placed there for the purpose.
“Loosen screw on tonearm head. After correc
ting the tonearm head, tighten screw.
(Fig, 6).
Fig. 5S Position of idler wheel
Remedy
a) Check connection at switch plate and
voltage selector
b) Check switch lever assembly (130)
c) 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 (150), clean platter
drive surface and motor pulley with grea-
seless solvent. (Once surfaces are cleaned
do not touch them your fingers).
Adjust position of idler wheel by turning
adjustment screw (5) so that when the fine
speed adjustment knob (13) is in the center
position the correct nominal speed is achie-
ved. (fig. 5)
Fig. 6