6
Setting Motor Speed
Please note:
In the first 4 hours of use from
starting up the motor, the speed tends to drift but
then settles down fairly permanently. To burn in
the regulator board components we recommend
at least 4 hours of running the motor at 33 rpm
(approx) before you accurately set the speed.
The thin output wires from the transformer only
carry 8 volts and are safe to handle.
Voltages
inside the transformer are dangerous so the
transformer case should not be unscrewed or
opened.
The switch box is designed such that when the
rotary switch on the front of the control box is
turned fully anti-clockwise the motor is off. One
click of the switch clockwise is 33.3 rpm and the
second click clockwise is 45rpm.
Please note:
The speed should only be checked
with the cartridge dragging on a centre track of a
record as the drag affects speed setting slightly.
Reading The Strobe
Place the strobe disc on the record to be played.
Play the record and watch the relevant ring on
the disc. Adjust the speed until marks on the ring
appear stationary while the record is rotating. It
sometimes helps to stare at infinity whilst doing
this as the marks become easier to see. You can
see the strobe effect in florescent light although
an ordinary bulb held about 2 feet from the
strobe disc will also work fine. The bulb flickers
at 50 Hz in the EEC and 60 Hz in the USA. You
can purchase bayonet fitting florescent bulbs to
fit normal lamps. Try to shut out daylight when
carrying out speed setting.
Note A:
P1 is the left hand adjuster when looking at
the rear and P2 is on the right.
Note B:
You cannot use many modern LED lights
or high frequency fluorescents because these
bulbs use a modified supply which is not 50 or 60
Hz as the mains is.
Motor Socket
Transformer Socket
PI Adjuster
for 33 RPM
P2 Adjuster
for 45 RPM
Adjust the motor speed as follows: using a small
flat blade screwdriver turn the screws of the 25
turn Trimmer resistors P1 and P2 on the regulator
board. P1 is for the 1st speed 33 rpm and P2
45 rpm. To increase speed, turn the screws
clockwise. The pre-set screw will not fall out and
may need a fair number of turns to set the correct
speed so keep turning until the speed changes.
If the screw reaches the end of it’s travel you can
usually hear a faint clicking.
Rotate the switch knob on the control box
clockwise to the first click i.e. 33 rpm setting.
Set P1 so that the platter turns at 33.3rpm. When
setting the speed, place the arm on the centre
track of a record so that the cartridge is tracking
the grooves. This ensures that the drag of the
cartridge is taken into account. Speed variations
of up to plus or minus 1% are quite common on
decks and the DC motor is capable of plus or
