Scott 312 output section inductor

39cross

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I was doing some recapping in a Scott 312 tuner and must have somehow messed up an inductor in the audio output section. At least I think it's an inductor, it's L102 on the schematic, 50mH. I attached a photo, circled the guilty party. If I jumper across it all works well, otherwise it's crickets on the right output.

What are these used for, as far as I could guess from a web search they can be used to filter high frequency AC?

Sooo......I guess I oughta replace it, although opinions are welcome. I found this at Mouser, would this be appropriate? https://www.mouser.com/ProductDetai...=sGAEpiMZZMv126LJFLh8y3ZZdlxu0Nf0jesk8WR/nRQ=

scott-312-inductor.jpg

Thanks,
Rick
 
Replacement part should work fine. Would replace on both channel to keep things matched.
 
Thanks Mike, and for the tip to replace both sides.

An interesting thing to note, I was just comparing the schematics between the 312 and the 312C. The audio amps are exactly the same, but the 312c uses silicon instead of germanium transistors. The QA2 equivalent in the 312C is a 2n3702, which I have a couple of. A swap works fine - easy to test because the original 312 uses socketed transistors.
 
Last edited:
I was doing some recapping in a Scott 312 tuner and must have somehow messed up an inductor in the audio output section. At least I think it's an inductor, it's L102 on the schematic, 50mH. I attached a photo, circled the guilty party. If I jumper across it all works well, otherwise it's crickets on the right output.

What are these used for, as far as I could guess from a web search they can be used to filter high frequency AC?

Sooo......I guess I oughta replace it, although opinions are welcome. I found this at Mouser, would this be appropriate? https://www.mouser.com/ProductDetail/JW-Miller/70F502AF-RC?qs=sGAEpiMZZMv126LJFLh8y3ZZdlxu0Nf0jesk8WR/nRQ=

View attachment 1372028

Thanks,
Rick
Yes I have two different Scott LT112B tuners which are the exact same tuners at the Scott 312C. The outputs use a 50mh inductor to filter out the 19Khz pilot after the desired L and R channels have been decoded. I also had problems with this 50mh inductor on TWO different Scott LT112B tuners. The 50mh inductor must use super thin wire to go infinite ohms. Likely the wire either tore or became disconnected inside the 50mh inductor.
 
Thanks Mike, and for the tip to replace both sides.

An interesting thing to note, I was just comparing the schematics between the 312 and the 312C. The audio amps are exactly the same, but the 312c uses silicon instead of germanium transistors. The QA2 equivalent in the 312C is a 2n3702, which I have a couple of. A swap works fine - easy to test because the original 312 uses socketed transistors.
I do not own either of these tuners nor do I have manuals. Usually, germaniums are PNP and silicons are NPN. Are you swapping the same transistor into these two tuners?
 
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