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Old 09-17-2011, 05:07 PM
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radiotvnut radiotvnut is offline
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RCA Victor R-93-B 78 RPM phonograph attachment

I was digging around in my junk and found this rather sad looking RCA Victor model R-93-B 78 rpm record player attachment that was designed to plug into the phonograph input jack of a radio. One interesting thing about this unit is that it uses a direct drive motor and the motor must be started by hand when the power is turned on. I'm guessing this to be from the '38-'40 time period. Does that sound about right?

I would like to restore this; but, there are some problems. The cartridge and the on/off/volume control are missing; but, I'm sure I can come up with those parts from something else. The cartridge will have to be something that is designed for high tracking pressure because there is no sort of counterweight on this tonearm. Otherwise, I'll have to figure out some way to add a counterweight. If I had the original cartridge, I'd have it rebuilt and be done with it. The Bakelite case is very dirty; but, I think it will clean up OK. The biggest problem is with the spindle and the platter. The platter wobbles on the rotor assembly and it looks like there should be something where the spindle is because what's there is too small for an ordinary spindle hole. The platter won't even sit straight and scrapes against the motorboard. The platter can be seperated from the rotor assembly by removing a clip from around the spindle. There are several rubber circles that seperate the actual platter from the rotor assembly and I suspect this was to cut down on the amount of motor noise that was transmitted thru the platter and picked up by the cartridge. I also suspect that there was some type of rubber that made up the turntable spindle and prevented the platter from wobbling around on the rotor assembly. The actual rotor assembly appears in good condition. It's just the platter and spindle that isn't right. Anyone ever worked on one of these or have any idea what I can do to fix the spindle/platter issue?









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Old 09-17-2011, 09:42 PM
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I'm surprised this unit has a volume control; after all, it was made to work with the audio section of a radio, which of course has its own audio amplifier and volume adjustment -- therefore, the phonograph attachment did not need a volume control, as the output cable was connected directly to the cartridge and terminated at the other end in an RCA pin plug. (RCA Victor's 1950s-vintage 45-EY-3 45-rpm changer, also for use with radios and TVs having phono inputs, was wired the same way.)

My best guess is that the hole on the motor board of your R-93-B 78 phono is probably for an on-off switch, maybe rotary but it could have been (and could be replaced today by) a push button; in a pinch, even a toggle switch would probably work. For testing purposes, you could even solder together the two wires from the switch and use a power strip to switch the unit, as well as the radio with which it is used, on and off.
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Old 09-17-2011, 10:28 PM
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ok, this is really a wild guess on my part, but it seems that the hole in the top is about where a support for the tone arm (when not in use) should have been located. I wonder if perhaps there was a support with a switch button that would turn on the power to the motor when the arm was lifted up?
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Old 09-17-2011, 10:45 PM
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I did find the service information at nostalgiaair and this did have a volume control on it. Also, the early 45 rpm players had a volume control. I think this was so that the output of the crystal cartridge could be compensated for whatever type of amp the record player was plugged in to.
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Old 09-19-2011, 08:11 PM
dieseljeep dieseljeep is offline
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Quote:
Originally Posted by radiotvnut View Post
I did find the service information at nostalgiaair and this did have a volume control on it. Also, the early 45 rpm players had a volume control. I think this was so that the output of the crystal cartridge could be compensated for whatever type of amp the record player was plugged in to.
I thnk when those things were new, they included a set of instructions on how to connect the unit to various types of radios. If connecting it to a TRF receiver, you needed the volume control because the first audio stage didn't have the volume control there. Also true of a non-AVC superhet. I heard RCA sold those things real cheap to bolster their record sales.
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Old 09-20-2011, 01:39 AM
bob91343 bob91343 is offline
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I used to own a similar unit. The spindle was very unusual, a major taper shape. The platter slid down until it jammed and what was left sticking up was about right for a record. I don't remember the cartridge, maybe an Astatic?

I used to have fun with it by starting the platter in the wrong direction and putting the arm way over on the other side of the spindle and playing records backwards. It's fun to try to figure out the lyrics sung by the vocalist. In particular, Francis Craig's Near You and Red Rose were what I had at the time, around 1947 I would guess.

The base was different; it had a teardrop shape with a small platter, maybe 8 inch with the arm mounted at the apex of the teardrop. It was plastic, maroon in color.
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Old 02-29-2012, 08:26 AM
Phototone Phototone is offline
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The spindle top would have had a rubber sleeve over the little round end, which brought it up to standard record hole size.
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Old 04-03-2012, 06:34 PM
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I had one of these many years ago. The owner thought it was broken because it wouldn't start turning by itself. Oiled up, it is a fairly quiet performer.
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