7YR772 Ch= 7B09A
Majestic Radio & Television Co.,(post 1932)
- Pays
- Etats-Unis
- Fabricant / Marque
- Majestic Radio & Television Co.,(post 1932)
- Année
- 1948 ?
- Catégorie
- Radio - ou tuner d'après la guerre 1939-45
- Radiomuseum.org ID
- 197252
SAMS Photofact
Cliquez sur la vignette du schéma pour le demander en tant que document gratuit.
- No. de tubes
- 7
- Principe général
- Super hétérodyne (en général); FI/IF 455 kHz
- Gammes d'ondes
- PO uniquement
- Particularités
- Tourne disque et magnétophone
- Tension / type courant
- Alimentation Courant Alternatif (CA) / 110-120 Volt
- Matière
- Boitier en bois
- De Radiomuseum.org
- Modèle: 7YR772 Ch= 7B09A - Majestic Radio & Television Co
- Forme
- Modèle de table boitier avec vouvercle
- Remarques
- Radio with Phono and Wire Recorder.
- Schémathèque (4)
- Photofact Folder, Howard W. SAMS (Set 42, Date 7/48, Folder 4812-17)
- Auteur
- Modèle crée par Ernst Erb. Voir les propositions de modification pour les contributeurs supplémentaires.
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Tous les appareils de Majestic Radio & Television Co.,(post 1932)
Contributions du forum pour ce modèle: Majestic Radio &: 7YR772 Ch= 7B09A
Discussions: 1 | Publications: 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!
Pièces jointes
- Majestic 7B09A Schematic (288 KB)
Bob Poole, 15.Dec.20