Zenith 1949 10" Porthole Television
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- เผยแพร่เมื่อ 26 ส.ค. 2024
- Back in the old days manufacturers gave their sets names, this model is called "The Mayflower"
It's nicknamed a "Porthole" by collectors because the screen is not masked off in a 4:3 ratio but left open so the whole face of the picture tube is visible.
This allowed them to advertise more square inches of picture while still using the same 10 inch tube as everyone else.
It also requires either stretching the picture vertically so everyone is tall and skinny, or over scanning the whole image so you lose some image off the sides but the vertical is correct. I compromised here, the image is a little stretched vertically but it's also overscanned enough so Broderick Crawford doesn't look like Don Knotts.
Zeniths of this era are know for being difficult to restore, this one wasn't too bad except as is typical, the Flyback transformer was burned up, it was a weak point on these sets and you will run in to it often.
All the supplies of easily found old stock replacements have been used up so a bad fly is a showstopper, or at least that's what I thought.
It turns out the very common RCA Flyback used in nearly every other set of the late 40's can be made to work, it wires in directly with no circuit mods other than changing the capacitor inside the deflection yoke to eliminate some ringing in the image.
Other than the bad Fly restoration was pretty much normal, replacing all the capacitors and some resistors that had drifted out of spec.
The picture tube is a Rauland 10FP4 that tests like brand new.
The 10FP4 is the aluminized version of a 10BP4 and is resistant to Ion burns and also has a brighter picture with better contrast.
Typical of a vintage Zenith the picture on this set is amazing, very sharp and clear.
There is a socket on the back labeled "Phone Vision" this was an early Pay Per View type scheme created by Zenith, it apparently never got past the experimental stage.
Phone lines didn't have the bandwidth to handle the actual analog broadcast of a movie or event so they were used to send the sync signal needed to watch the program while the program itself was received over the air in the normal fashion, at least I think that's how it worked..
Note: There are Brass plated doors that cover the controls but they are flipped down in this video. - วิทยาศาสตร์และเทคโนโลยี
Wouldn't this 'over scanning' by the electron beam inside the CRT cause damage to the aquadag coating on the sides of the tube? Did it even has this coating??
@Crisologowilx13 Yes, provided your Cable box has an R.F. output (i.e. Ch 3) or a Component or Composite output that can be run through an R.F. Modulator.
@Vintagetvs Oh I didn't know you could hook up a DVD player to that oldie!
Nice image quality for a 1949's TV receiver & CRT screen. Perfectly circular screen - - And image? Was this 'television' programming here made for this type of television? Or was it film material adapted to this 'portal' TV by editing and or cropping of the pictures?
Since nearly all early TV picture tubes used circular CRT screens, why didn't they use spiral scanning instead of horizontal sequential scanning? Not compatible with Iconoscopes (Emitrons)?
I can only guess that spiral scanning would probably be a lot harder to achieve, it would probably have some weird effects on the image as well. The image the TV displays is actually square, all TV's make a square image (well rectangular actually) it's just zoomed in so much the corners are cut off. .
We had one of these when I was a little kid. Mom watched The Edge of Night on it. It died in 1963, I think, and dad bought a new Admiral B&W. Didn't miss the porthole, though.
@Vintagetvs oh, nice and tnx for the reply:)
Which model RCA fly back did you use? I am picking up a mayflower soon.
+Samrr Fly1, used in the 621, 630, 721 and lots of other early sets.
How did he pause that at the end??
very nice set
could it connect to the cable and watch Disney?
@soccerwin55
I Just pressed "Pause" on the DVD player.
amazing!!
Highway Patrol Lol
Wouldn't this 'over scanning' by the electron beam inside the CRT cause damage to the aquadag coating on the sides of the tube? Did it even has this coating??
The tube has a conductive coating on the inside and outside of the bell area, it forms a filter capacitor for the high voltage supply and accelerates the electron beam to the screen.
The overscan doesn't affect it, it's not really in the area that gets scanned anyway.
This particular 10FP4 tube has an Aluminum coating over the phosphor which makes the image brighter and the contrast better, it also prevents Ion burn to the screen.