Ron has a good point. Most of the early electric motors that were
used in the first electrified phonographs were of the "universal" type.
I seem to remember seeing this type in the early Columbia electrics.
Meaning they had windings of wire in both the armature and in the stator
magnets. This is unlike the pure induction motors that were typically
used by Victor in this period. The rotor of an induction motor has no
obvious wire in the rotor that comprises a winding, so it's generally
easy to identify it as an induction motor. The armature of a universal
motor has a commutator with electrical contact brushes that is required
to switch and energize the several sections of the armature at the
correct times to interact with the magnetic poles in the stator. Motors
of this type can run on either AC or DC current, hence the term
"universal". Since the household power commonly in use at that time
could be anything from low voltage to high voltage DC (the Edison
system) or variations of AC voltages, universal motors were found to be
the most compliant with these early electrical systems. Maybe as a
consequence of the several voltages available back then, most of the
early universal phono motors were designed to operate on a fairly low
voltage of around 24 to 60 volts or so.
So in order to use them with 120 volts power that is universal
throughout the USA today, you need to add a "ballast" resistor in series
with the motor to reduce its operating voltage to whatever it was
designed for. Some of these motors have an identification plate
attached to them that states their operating voltage range. But some
don't. So unless you have some other service data that tells you what
the motor voltage should be, you have to figger that out by trial and
error. The easiest way to do this is to hook up the motor to a variable
voltage device such as a variable autotransformer, typically referred to
as a "variac" or a "powerstat". These devices have a continually
variable output voltage, usually determined by a knob that slides a
contact brush around the periphery of a toroidal winding on a magnetic
core. Then slowly raise the voltage on the variac up from 0 and observe
the operation of the motor. Motors such as these had their speeds
dependent on their applied voltage. In order to make them suitable for
phonograph use where you want a constant speed, the motor assembly
usually had a mechanical flyball governor attached to it which operated
in a manner similar to the flyball governors that were used on spring
motors. The electric motor functions as a torque motor and its speed is
controlled by the mechanical braking action of the governor. So you
would need to have the governor mechanism attached and functioning while
you try to determine the motor voltage. Crank up the variac until the
governor engages the brake mechanism to provide the desired platter
speed of 78 or 80 rpm. If you have the motor mounted in the player,
play a record which will produce some additional drag on the motor and
raise the variac voltage until the playing record is running at the
desired speed at the outermost diameter (greatest drag). Then notch the
variac voltage up a little more, say 5% to 10% or so to provide some
reserve torque for "draggy" records. Note the voltage you are providing
to the motor. Then you can either leave the variac in place
permanently, or you can figger out how to reduce the 120 volt household
voltage to what the motor wants to see. You can do this by inserting a
big, power-hungry wirewound resistor in series with the motor, which
needs to dissipate a lot of power and will get VERY HOT in operation,
which is why they are typically wound on a ceramic core. This is what
most of the player manufacturers did in their original designs. This
allows the motor to continue to be used with either DC (maybe if you're
still living in the downtown New York City subway system) or typical
AC. If you only plan to use the motor with AC, you can look for a fixed
transformer that provides the required voltage change that you need.
You'll need to use a fairly hefty transformer for this application since
the motor is probably consuming 25 watts or so and the transformer will
have to provide sufficient current for the job.
In summary, your Columbia motor is probably a low voltage universal
type. So you DO NOT want to hook it up directly to your 120 volt
household current. Doing so will burn it up pretty quickly. Perform
the variable voltage check described above to determine the proper motor
voltage and then find a way to step down your household 120 volt outlet
power to what the motor wants.
Greg Bogantz
On 11/6/2019 5:11 PM, Ron L'Herault via Phono-L wrote:
You should be able to figure out what connects to what with visual
inspection and a meter that measures continuity. Most of the old motors
went through some kind of resistance device, a long coil of wire on a
ceramic tube, for instance, as a way of controlling voltage. You may want
to submit the question to the Electrola group., electr...@yahoogroups.com
but don't wait too long. Yahoo is abandoning these mailing list type
groups.
Ron L
-----Original Message-----
From: Phono-L [mailto:phono-l-boun...@oldcrank.org] On Behalf Of Robert
Wright via Phono-L
Sent: Tuesday, November 05, 2019 3:39 PM
To: Antique Phonograph List
Cc: Robert Wright
Subject: Re: [Phono-L] Columbia Grafonola - electric motor question
Anyone? No one here knows about these Columbia electric motors? I would be
shocked if that were true!
On Oct 25, 2019, at 5:35 PM, Robert Wright via Phono-L
<phono-l@oldcrank.org> wrote:
Hello, all! Got a question on behalf of a lovely couple I get this weekend
regarding a big, beautiful Columbia Grafonola. I was going to find them a
crank for it, since they thought that's what was missing, but upon further
inspection, it's got the same situation as in the attached ad. Pretty cool,
and super clean as well.
Problem is: how do you connect this motor to an outlet? No cable included
(that's the easy part), couple of loose wires, not sure what does what... I
only know Victor induction motors! Anyone have a schematic for getting this
thing wired up back to original spec? I'd sure love to help these folks if
possible.
Thanks from them and myself in advance!
Best,
Robert
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