• Year
  • 1948 ?
  • Category
  • Broadcast Receiver - or past WW2 Tuner
  • Radiomuseum.org ID
  • 197252

Click on the schematic thumbnail to request the schematic as a free document.

 Technical Specifications

  • Number of Tubes
  • 7
  • Main principle
  • Superheterodyne (common); ZF/IF 455 kHz
  • Wave bands
  • Broadcast only (MW).
  • Details
  • Record Player + Tape Recorder
  • Power type and voltage
  • Alternating Current supply (AC) / 110-120 Volt
  • Material
  • Wooden case
  • from Radiomuseum.org
  • Model: 7YR772 Ch= 7B09A - Majestic Radio & Television Co
  • Shape
  • Tablemodel, Box - most often with Lid (NOT slant panel).
  • Notes
  • Radio with Phono and Wire Recorder.
  • Author
  • Model page created by Ernst Erb. See "Data change" for further contributors.

 Collections | Museums | Literature

Collections

The model 7YR772 is part of the collections of the following members.

 Forum

Forum contributions about this model: Majestic Radio &: 7YR772 Ch= 7B09A

Threads: 1 | Posts: 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!

Attachments

Bob Poole, 15.Dec.20

Weitere Posts (5) zu diesem Thema.