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I was at an auction that had several upright phonographs that had sat in a barn for what looked like decades. The cabinets were beyond repair so I wasn't able to take them home. I also couldn't let them go as cheap as they were so I bought them all and took everything that was worth anything off of them and carted it all home.

One of the phonographs was a C-250 Diamond Disc and recently while talking to a friend of mine who is also a collector, I mentioned wiring on the motor of the C-250. We talked about it a bit and he informed me that it was an electronic brake that was used on some C-250s as well as some of the art models. So I took a few pictures and am happy to take more if anyone would like any specific views. I don't have the battery for it, (left it in the cabinet as I thought it was an old junk battery thrown in the cabinet for storage) but everything else is there. Here are the pictures of the Duncan Automatic Stop.

This is a picture underneath. You can see the wiring as well as the solenoid coil that actuates the brake mechanism.




Here is the top. The brake is released to stop the turntable by meansof the solenoid which is located under the black cover seen in this photo.



Here is the end with a connection that would connect to the reproducer, that of course, I don't have.



I can post other pictures or closeups if anyone would like. Also, if anyone has any other information on these please let me know. I would like to use this brake sometime but need to find a proper reproducer and maybe a wiring schematic. It's definitely an interesting addition to a otherwise normal C-250.

Does anyone know how many of these automatic stops were produced?

Thanks for posting! The system is a lot more involved than I thought it was, but at the same token, it appears that it is possible to identify a player with the system (or that had the system) just by looking at/for a few key things.

Has anyone encountered a DD player that had the Duncan stop removed at some point?

SonnyPhono wrote:Does anyone know how many of these automatic stops were produced?

I don't know of any factory documents to answer this, but the Duncan stops are found occasionally on C-250s. They're not rare, but they are interesting, and work reasonably well if you don't mind fussing with the battery (or an HO train transformer as I use).

I have a mechanism in the bone-yard where someone disconnected the solenoid, but it's still hanging there by the wires. There's not much point in removing the Duncan stop - - simply remove/disconnect the battery and the device is disabled.

By the way, Sonny, the mechanism you picture appears to be a C-19, unless it's a late C-250 lacking the pinstripes on the bedplate. Is there such an animal?

George P.

If a machine had the Duncan stop factory installed, then the wire passes through a tube on the horn. That tube would be dead giveaway that a Duncan stop had been there originally if none is found. Also, the mechanical brake lever is completely replaced by the Duncan brake lever, so if the stop is missing, the machine would have no brake lever at all unless someone took the time and trouble to replace it with a mechanical lever.

Lastly, there is usually a black-painted sheet metal strap inside the back of the horn compartment that secured the dry-cell battery that energized the stop. A dead giveaway since these are out of reach and usually not molested.

You shouldn't need a wiring schematic per se. It is a simple loop to ground. The hinge block on the reproducer is replaced with an insulating block made from a 'plastic' material (like hard rubber or Bakelite). The electric current is in the weight of the reproducer via the plug on the wire that plugs into the weight. The limit loop on the reproducer has just a bit of insulating material on the 'V' portion so that the reproducer can be raised and lowered without completing the circuit, but the straight sides of the loop are left uninsulated. At the end of a record, the stylus hangs in the groove and waits for the reproducer body to advance. When the bare side of the loop touches the pin, it makes the circuit activating the stop solenoid and the brake releases to stop the turntable. So + to the weight and - to the solenoid. That's it!

phonogfp wrote:

SonnyPhono wrote:Does anyone know how many of these automatic stops were produced?

I don't know of any factory documents to answer this, but the Duncan stops are found occasionally on C-250s. They're not rare, but they are interesting, and work reasonably well if you don't mind fussing with the battery (or an HO train transformer as I use).

I have a mechanism in the bone-yard where someone disconnected the solenoid, but it's still hanging there by the wires. There's not much point in removing the Duncan stop - - simply remove/disconnect the battery and the device is disabled.

By the way, Sonny, the mechanism you picture appears to be a C-19, unless it's a late C-250 lacking the pinstripes on the bedplate. Is there such an animal?

George P.

George, I had a C250 with plain black bedplate and Duncan mechanism some years back. I've also got a W250 with plan bedplate and Duncan mechanism. It was a featured phono here awhile back. I've also seen at least one B250 with plain black bedplate. I don't think it was altered. Could be Edison again just putting machines together with what's available?

Bruce,

Thanks - I've wondered if the last of the pre-1919 series machines had gone over to plain bedplates. Now the B-250 with a plain bedplate would make me suspicious, since we're dealing with a 1915 cabinet and a 1918/1919 mechanism. Still, stranger things came out of West Orange - - especially for export.

Thanks for the info, Bruce!

George P.

phonogfp wrote:Bruce,

Thanks - I've wondered if the last of the pre-1919 series machines had gone over to plain bedplates. Now the B-250 with a plain bedplate would make me suspicious, since we're dealing with a 1915 cabinet and a 1918/1919 mechanism. Still, stranger things came out of West Orange - - especially for export.

Thanks for the info, Bruce!

George P.

George, isn't the B250 just an A250 cabinet with the newer Standard Disc mechanism incorporated (end of 1915)? That still does not explain why/whether a B250 with a flat back bedplate would be correct, just would make it more "possible".

Bruce,

Oh, there's no doubt that a later "250" mechanism would fit into a B-250 cabinet, but the later plain bedplate should have appeared at least 3 years after the discontinuance of the Pooley cabinet. It just seems anachronistic, especially considering the B-250's short production life.

George

Does anyone have a picture of the reproducer tailweight (I presume the wire from plugs into this somewhere)?

tarheeltinkerer wrote:Does anyone have a picture of the reproducer tailweight (I presume the wire from plugs into this somewhere)?

Sorry I dont have a picture that would show it clearly but yes the wire plugs into the back of the reproducer so if you have a duncan mechanism you need a special reproducer. The limit pin is also slightly modified.