Origin Live DC Motor Kit - Manual (Page 4)

Page 4
S E T T I N G T H E M O T O R S P E E D
NOTE:
In the first 4 hours of use from starting up the motor, the speed
tends to drift but then settles down permanently. To burn in the
regulator board components we recommend at least 4 hours of
running the motor before you accurately set the speed.
The thin output wires from the transformer only carry
8 volts and therefore 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.
NOTE: The speed can only be checked with the cartridge
dragging on a centre track of a record as the drag affects
speed setting.
I N S T R U C T I O N S F O R R E A D I N G T H E
S T R O B E
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 stobe 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.
If this photo is not quite the same as your control box you
can identify P1 & P2 as they are labelled on the circuit
board.
Adjust the motor speed as follows: using a small flat blade
screwdriver turn the screws of the 25 turn resistors P1 and
P2 on the regulator board. These are accessible through
the hole in the underside of the control box (See diagram
below). P1 is for the 1
st speed 33 rpm and P2 45 rpm. To
increase speed, turn the presets 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.
Note for “Standard” control box, to increase motor speed
turn the set screw anti-clockwise and vica-versa.
Set the switch on the control box 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 2% are quite common on decks and
the dc motor is capable of plus or minus 0.1% accuracy. Use
the strobe disc provided to set the speed (full instructions
are on the card). However if you have problems using the
strobe card, then count the rpm using the following method.
Counting the 33.3 revs per minute is best accomplished
by placing a small piece of sticky tape on the perimeter of
the platter and then counting 100 revolutions. 33.3 rpm
is exactly 100 revolutions completed in 3 minutes. To save
time in the early stages it is easiest to count 50 revs in 1
minute 30 seconds (or 25 revs in 45 seconds) and save the
100 count for the final check.
Please note the following points when setting the speed.
Firstly all the figures below are based on setting the speed on
the deck using the centre track and letting the deck play for
a good 5 minutes beforehand with the stylus on the record
so that the whole system has settled down. The regulators
seem to take about 5 minutes to warm up, so speed is about
2mins 58 seconds for 100 revolutions when the system starts
from cold. In other words it is 2/180 x 100 = 1 % fast when
started from cold. Speed variation with the dc motor varies
minutely depending on the track played and cut of record.
Click the rotary switch to the 2nd click clockwise and set P2
so that the platter rotates at 45 or 78 rpm (if you wish) using
the same procedure as outlined above.
The dc motors are noisy to begin with and are never
completely silent in comparison to a/c motors. This is
thought to be due to a different type of precious metal
brush. Having said this they still sound a great deal better
in performance terms. To assist “running in” you can turn
the speed right up via the control box. The motor then runs
at high speed. Allow this for approx 4 hours. After the
running in period reset the motor speed. The motor should
then be run for approx 3 days under load (i.e. turning the
platter) to free it up from vibration and to “bed in” the
bearings.
Like most turntable manufacturers we recommend that you
leave the turntable running between changing records as this
reduces the belt wear that occurs with constant stopping and
starting.