Adjusting a 1934 Victor model 341 radio/phono

I have a 1934 Victor model 341 radio/phono. I think it is the first model advertised as having Magic Brain. The radio needs work, but I do play the phonograph. This machine has two speeds, 78 and 33, but I just use the 78, since you need special needles to play the old transcription Victor 33's. All I had done so far was have George Eppel rebuild the pickup. This model has a pusher type record changer and the cobra style tone arm, but the record changer on this machine does not work. I think something is out of alignment because when I play some records, it starts to bind up in the middle like it's ready to shut off. If a record plays to the end, it only shuts off 1 out of 10 times on eccentric groove records. When I grab the pickup to return it to the base the turntable starts spinning again. So something is amiss. Does anyone know what I should do? I'm just talking about adjusting the turntable so it shuts off at the end of a record, and doesn't turn back on when I put the pickup back.

Victor never had a Cobra tonearm to my knowlege. Only Zenith. Need Pictures.

Thom

I take it, by "cobra" you mean the cobra winged tonearm that RCA produced in the 1930s to offset the tendency of the pickup and tonearm to twist sideways when the record was played.

I don't know if it will help you, but you can download a PDF version of the schematic from this page: http://www.nostalgiaair.org/Resources/910/M0014910.htm

(To view the file, click on the small "eye " icon; to save it, click on the small floppy disc icon.)

This image is taken from the 341 schematic:

Here is a photo of one:



It's a throwoff changer, not a pusher. This is a pusher:

My Victor 341 is the pusher type as shown in your photo. I called it a cobra arm because that's what it looks like to me. Sorry for the confusion, as I know in the 40s Zenith had a tonearm called the Cobra. So I guess no one has an answer for me on how to adjust this thing. I guess I'll have to try to read the manual! Marc.

Now I am more confused. RCA never made a pusher changer with that arm. They made two kinds of changers with that arm, plus some manual players:

The throwoff:


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and the repeating changer:


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The next series of RCA changers (also called Magic Brain) were knife type (also called "slicer):


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The Magic Brain two-side changer (knife type) is here:


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Zenith used this cobra tonearm in its Cobra-Matic changers:


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RCA didn't have a real pusher changer (other than some Admiral RC-200s they bought) until after World War II. They did use this one. Zenith also used this, with a cobra-shaped tonearm head:



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If you really have a throwoff changer (the first image), and it is stopping the turntable with the arm on the record, one of the following is happening:

- The auto shutoff (see below) is activating while a record is still holding up the arm.
- The mechanism is jamming.
- The idler wheel is shot.

One version of this changer repeated the last record. The other version shut off the motor when the needle dropped below the turntable surface because no record was there (it had been ejected).

Note that those throwoff changers had a position trip. The trip occurred when the arm reached a certain distance from the spindle. There is a screw on the underside to adjust it, but it will not work on all records.

The change-cycle cam is under the turntable, and the cycle completes in one turntable rotation.

Although Victor invented the eccentric trip, RCA didn't use it until they made the knife-type changer.

I would not play any records I cared about on any of the RCA record changers shown, except the last one.