CED VideoDisc and Player Discussion

[Smoky Pond]

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Some of you might get a kick out of how my wife and I watch our CED collection:




This is a 1947 RCA 648-PV rear projection television, radio and phono console with a 1983 SKT400 hooked up to it. I acquired the 648-PV from the estate of the original owner and restored it several years ago. It's great for watching old black and white movies. If you haven't already guessed, the title playing is "The Compleat Beatles."

Many people believe that the early rear projection RCA sets were unpopular due to the dimness of the picture. That is totally not true. With a good projection tube, the picture is quite bright. I believe that the problem (aside from high cost and very little advertising) was the in-home setup of these sets. They were shipped to the home, for the most part, dis-assembled. The assembly, setup and alignment of the optics AND electronics is no small task. A TV tech could probably install 5 standard sets in less time then it took to setup one of these properly.

The CED player will come in handy when analog TV broadcasting comes to an end in February of 2009.

Now that I think about it, it's almost unreal to think that this TV has been able to receive TV broadcasts continuously since the day it was built over 60 years ago, with no modifications. All that will end next year.

You can see more pictures this TV (inside and out) at:

http://www.smokypond.com/gallery/pictures/antique_electronics/

BTW, for those of you that remember the dial-type channel selectors, this TV's tuner includes channel 1!

-Matt
_________________
"Born after my time!"
Smoky Pond Farm Website

[pamperchu]

wow that TV is super cool. I wonder how much that set went for when it was new.

[Smoky Pond]

Cost was about $1,400 in 1947. That's equivalent to $13,500 in 2008 dollars!

-Matt
_________________
"Born after my time!"
Smoky Pond Farm Website

[pamperchu]

wow and what was the price of a new house then. hmm new house or a new TV...

[Smoky Pond]

The set came from one of the Briggs family homes in Grosse Pointe, Michigan.

Walter O. Briggs was a wealthy Detroit industrialist. He owned the Detroit Tigers baseball club from 1920 until his death in 1952. Legend has it that he bought this set, which had a very large screen for its time, right after he struck a deal with a local television station to broadcast his Tiger baseball home games.

You can read more about him at:

http://en.wikipedia.org/wiki/Walter_Briggs,_Sr.

-Matt
_________________
"Born after my time!"
Smoky Pond Farm Website

[Rixrex]

I recall seeing that same type set at my Dad's radio-TV repair shop when I was a kid, though it might have been a later and/or different model. As I recall, it was about a 30" diagonal screen. Looking at the 17" wide CED player there next to it, that seems right, somewhere between 29-31", is that correct?

I remember when he had it apart to repair, that the set had one CRT inside with lens system that reflected off a mirror onto the back of the screen. I think that the CRT inside was somewhere between a 9 to 13 inch circular-faced tube and pretty long too. The rectangular "matte" apparently was created by the rear projection screen with the excess image just falling off the screen to the sides. Is this how yours works?

I remember that once my Dad replaced the bad CRT, the alignment and focus were very simple adjustment in comparison to newer rear-project sets as it was the single CRT. I would bet that if you could find one of these units non-working, that you could retrofit it with a single-tube color CRT system with CRT tube of about the same size as the original, but I don't know if the lens and mirror system created the reversed image for rear projection or if the CRT itself scanned in reverse.

Certainly could be a fun project for a technically adept person! I'd pick either a Trinitron TV tube or a progressive scan PC monitor with video input adapter of some sort.

However, I would replace the CED player shown with a wood-grained model and add a wood-grained VHS and/or Beta VCR, for the sake of similar appearance.

[Smoky Pond]

Unfortunately, there is a little bit more to it than that. You may have seen a set like those made by U.S. Television that projected directly from the CRT through a lens, up to a mirror then onto the screen. This RCA system utilized Schmidt-Cassegrain optics, which is a much more efficient way of gathering light. It uses a 5"CRT (a 5TP4, which is a true projection type CRT) that is located in a large aluminum optical barrel. The CRT points down towards the floor.



A spherical mirror is located in the bottom of the optical barrel. The image is reflected around the CRT through a corrector lens that is located around the neck of the CRT at the top of the barrel (note that the full image is reflected from every point on the mirror), then up to a 45 degree mirror, then onto the back of a 26" diagonal screen that is actually a lenticular fresnel lens (concentrates light in a relatively narrow vertical angle and uses some of this "spare" light to help widen the viewing angle somewhat).



The rectangular shape of the picture is created by the raster. The image does not fill the face of the CRT, so there is very little overscan. Excessive overscan would hit the mirror and be scattered across the back of the screen, lighting up the areas that should be dark or black.



There are 6 optical adjustments:

- Optical Focus
- Alignment of Optical Barrel
- Lateral Optical Adjustment
- Horizontal Optical Adjustment
- Corrector Lens Centering
- and 2 Optical Barrel Tilt Adjustments (Front to Back and Left to Right)





Note that the spherical radius on the face of the projector tube is extremely critical. If the radius is too large or too small, optical focus across the screen can not be attained. In fact, many of the adjustments would not come close to anything one would consider satisfactory, especially if the face of the CRT is not truly a spherical radius.

Yes, it would be nice if the SKT400 had a wood-grained cabinet. However, many of the earlier CED players with wood-grain used platters that were smaller than the discs themselves. These players are the reason that many CED's exhibit noise and skips at around the 12 minute point during playback. Because of that, I will not play my CED's on any of these older players.

-Matt
_________________
"Born after my time!"
Smoky Pond Farm Website

[Rixrex]

I see, this is a projector TV using the same principles as an optical reflective telescope, rather than those of a refractive telescope as do the more common type of rear projection sets, though they all have the fresnel lens screen in use. Quite unique, and not one I'd ever seen before in the shop.

It is possible to put a wood grain case onto your CED player. You'd have to take it off of an earlier model of the same body design that uses the same case which has a wood grained finish, meaning only the back part of the unit that comes off with two screws, and that covers the top and sides, and just leave the rest alone. I think some 200 models have that wood grained finish and maybe some other lesser models. Probably can get it from a non-working unit.

[Jesse Skeen]

A shame that TV had to witness the horror that is the Fox network (and bugged TV in general).

About 10 years ago I saw a 1950s console TV in a thrift store turned on, it worked reasonably well except that the picture had shrunken to a square in the middle of the screen. It was tuned to a "trash talk show" with everyone yelling at each other- I thought that was kind of sad considering the stuff it must have shown when it was new.
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Videodisc and stereo sound- there's no better value around!

[pamperchu]