7YR772 Ch= 7B09A
Majestic Radio & Television Co.,(post 1932)
- País
- Estados Unidos
- Fabricante / Marca
- Majestic Radio & Television Co.,(post 1932)
- Año
- 1948 ?
- Categoría
- Radio - o Sintonizador pasado WW2
- Radiomuseum.org ID
- 197252
SAMS Photofact
Haga clic en la miniatura esquemática para solicitarlo como documento gratuito.
- Numero de valvulas
- 7
- Principio principal
- Superheterodino en general; ZF/IF 455 kHz
- Gama de ondas
- OM (onda media) solamente
- Especialidades
- Tocadiscos + Grabadora de cinta
- Tensión de funcionamiento
- Red: Corriente alterna (CA, Inglés = AC) / 110-120 Volt
- Material
- Madera
- de Radiomuseum.org
- Modelo: 7YR772 Ch= 7B09A - Majestic Radio & Television Co
- Forma
- Sobremesa, caja, normalmente con tapa (panel no inclinado).
- Anotaciones
- Radio with Phono and Wire Recorder.
- Documentación / Esquemas (4)
- Photofact Folder, Howard W. SAMS (Set 42, Date 7/48, Folder 4812-17)
- Autor
- Modelo creado por Ernst Erb. Ver en "Modificar Ficha" los participantes posteriores.
- Otros modelos
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Donde encontrará 418 modelos, 174 con imágenes y 358 con esquemas.
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Colecciones
El modelo 7YR772 es parte de las colecciones de los siguientes miembros.
Contribuciones en el Foro acerca de este modelo: Majestic Radio &: 7YR772 Ch= 7B09A
Hilos: 1 | Mensajes: 5
I'm working on my Majestic 7B09A, my first full restoration. As I am going through the unit doing a recap, I have run across a capacitor that I think is the dreaded "death cap", but I'm not sure. It's C14 (.1 uf, 250 volt), which the Photofact lables as a "Line Isolation" capacitor. It's tied between chassis ground (as is one side of the input AC) and B-, with a 220K resistor across it. I'm attaching the schematic for reference and I've circled the section in question.
I'm thinking this cap needs to be replaced with a Safety Cap. I researching them, it appears that only X2 caps come in the .1 value, which would make this application "across the line". However, the connection to B- is causing me confusion, as this point is the only reference to B- and uses the Earth Ground symbol, which is used throughout the rest of the chassis circuitry.
Is B- actually a DC circuit ground point and the .1 cap is providing noise filtering between it and the AC line?
Man, I've got a lot to learn, but this is so much fun!
Anexos
- Majestic 7B09A Schematic (288 KB)
Bob Poole, 15.Dec.20