Quote:
Originally Posted by Jeffhs
It probably is an Emerson set. I saw at least two Emerson branded tubes in the chassis.
I don't know where you saw that Emerson logo. I looked at the ballast tube and didn't see anything but a perforated cylinder over the tube itself; there was no logo on that cylinder, unless I was looking at the wrong part.
BTW, this is the first TV I've ever seen that uses a ballast tube in the power supply. Every set I've ever worked on has had a power transformer and at least one 5U4 rectifier, or series string filaments with seleniums.
That this set uses a ballast tube probably dates it to the late 1940s--'47 or '48. By 1950, however, I am sure the 5U4 had taken hold as the rectifier tube of choice in most TVs, although my folks' second set, a 1955 Crosley Super V 21" b&w console, still used selenium B+ rectifiers. That set had two such rectifiers, probably wired in parallel across the output of the B+ supply. The plate voltage for the tubes was probably taken directly from the output of the rectifiers and fed through at least one filter capacitor.
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The set, definately is an Emerson 1949, 12" chassis from a TV, radio, phono combination.
The first set, my parents bought was the TV only model, using that type chassis. A smaller type console, where the speaker was as large as the picture. The ballast was for surge limiting of the two power supplies.
The CRT went weak, when the set was about four years old. They gave it to me, to take it apart when I was about ten years old.
Regarding the Crosley set, that model used a voltage doubler, two seleniums and a voltage doubling cap, before the two rectifiers and two caps and a choke to furnish the B+ voltages. It also used the audio output tube as a voltage divider. I common scheme that many manufacturers used.
