The Dream is Alive: The CBS 205 Lives On
 

Hello All

In a recent thread, YOUR DREAM TELEVISION http://audiokarma.org/forums/showthread.php?t=159280

Sandy G posed this question "....A 1954-55 era 19" color set-Did any of those survive intact & working ?"

I am very pleased to report I recently completed restoration of my CBS Model 205 19" color TV. This set dates from summer or fall of 1954.

Scott AVitt at Hawkeye picture rebuilt the 19VP22 CRT last February, using an off the shelf 21" round tube gun, as there are no exact replacement guns available for the 19VP22. This tube was rebuilt using the custom made "double cycle " oven control cam, which allows Scotty to process the tube using a 6 hour oven cycle, as opposed to the standard 3 hour cycle, and operates the oven at a reduced temperature. The hope was to improving the chances that the CRT would survive the trip through the oven. The 19VP22 has a large metal flange and glass to metal frit seal around the front of the cRT, similar to the predecessor 15GP22 CRT, but features the CBS-Hytron invention of placing the phosphor dots directly on the screen. The first photo shows an original 19VP22 (left) and the rebuilt 19VP22 (right). Note the reduced length of the neck of he rebuilt tube, due to the shorter replacement gun length. Fortunately, the CRT survived the rebuild, and the replacement gun works very well. The only adjustment that had to be made was to reduce the CRT G3 focus potential from the 9-10KV required by the 19VP22 to the 3-4KV required by the replacement gun. A simple rebalancing of the resistive divider network around the focus pot accomplished this.

The CBS 205 featured a split chassis design, with an RF/IF/Chroma/Video/Audio chassis, and a LV/HV Power Supply Deflection and Convergence chassis. For those of you who like to look under the hood, the next 5 photos show top and bottom views of the chassis.

Rebuild of the chassis was pretty much the standard process. First, replace all the wax paper and electrolytic capacitors. I also replaced the silver micas, as I did not want to be back in the set later on chasing a bad mica capacitor. I replaced any grossly out of tolerance resistors, checked and replaced tubes as required, checked all inductors and transformers for continuity, and then brought it up on the VARIAC to see what it would do.

In actuality, the rebuild of this set has taken place over a number of years. The steps just described were initially completed over the course of several months, and I brought the set up on the VARIAC, and had nominal performance. But the CRT was very weak, and the Beltron rejuvenator would not make it any better. So I set it aside and moved on the greener pastures, hoping someday to find a better CRT.

Eventually I acquired a DUD 19VP22, still under vacuum, from a friend and then managed to get all the ducks in a row required to have Scotty rebuild the CRT. A fantastic video on DVD, captured and produced by Bob Galanter, documents the rebuild of this tube and several others at the Hawkeye facilities. Alas, I was unable to attend this histoic event in person. Bob will debut this fascinating video at the ETF convention.

Upon receipt of the rebuilt CRT, I set up the chassis on the bench with the CRT and brought it up. The only modifications required were to change the focus voltage from the 9-10KV required by the 19VP22 gun to the 3-4KV required by the replacement gun. This was accomplished by a straightforward rebalancing of he resistive divider network around the focus pot. Next I gave the set a swept IF alignment, and now the set works very well.

The convergence is not good at the edges, but the CBS service data for the set indicates this is to be expected. And the purity could be better, but after all, that cRT has has quite a long and rugged existance over the years. And this was the first magnetically converged CRT.

The next 4 photos are vanity shots of the cabinet. Quite a handsome TV, no? When I got the set, the only knobs it came with were the channel selector, UHF and fine tuning (3 knobs on one shaft). A generous friend loaned me one each of the 3 knob types used for the "small" knobs. Using silicone RTV rubber, I made casts of each of these 3 knobs, and cast replicas in liquid plastic. The next photo shows the original knobs (left) and the reproductions. Not perfect, but a lot better than no knobs! I elected to tint the knobs dark black because I could not cast all the knobs simultaneously, so color matching the original dark grey color would have been very difficult. But they look good on the set, and seem to match the channel selector knob pretty well. You serious students may have noticed that my on/off volume knob is actually a channel selector knob. This was the best I could do rummaging around through my knob box. My friend who loaned me the "small" knobs was missing the channel selector knob and the on/off volume knob on his set. So my next task is to reproduce my channel selector knob for him, then make a version of that same knob with the embossed channel numbers removed. This will give both of us a complete set of knobs Hooray! The original on/off volume knob had "on/off volume" embossed on the front of it. Anyone out there seen this knob? I would certainly be interested.

The last couple of photos are screen shots of the set operating. The photos do not do the set justice, it looks better in person.

Well, that is about it for the CBS 205. It has been a long an fulfilling adventure bringing this old gal back to life.

Hope to see many of you AKers at the ETF next weekend.

BRAVO!!! {clapping} Great set! Thanks for sharing! This is definitely a holy grail set!!!!! I'll be at the ETF!!! See you there!

That is awesome John! I wish i could make it to the ETF convention this year but will have to wait till next year now. I hope to make it to the museum though in the near future.
-Tony

i think you TV guys are kinda weird, and i still think that is completely awesome

Yes, that is awesome,, thanks for the great post.
Dan

KINDA weird ?!? Just "Kinda" ? But we are Men on a Mission, preserving history. There is a certain nobility to our weirdness..People in the year 2525 might well wonder about this strange device called "television"...Maybe our efforts will be appreciated someday..

A++

---

Just wanted to add my two cent. I was at John's yesterday and saw this set in operation. It is nothing short of fantastic. The set itself is quite impressive from a standpoint of cabinetry. It has these impressive vertical louvres at the rear of the side panels and gives the set a most impressive and individual character.

Picture is nothing short of astounding for a set of this vintage. Color saturation is very good and it displays a picture that is reminiscent of a Technicolor motion picture.

John did a fantastic job in restoring this set. It was a labor of love that not only took a long time but a great deal of persistance in persuing the rebuild of the 19vp22 crt, without which, this set would never have been reborn.

Congratulations John! You done REAL GOOD!

Bob

john....great job preserving a piece of Television history. Do you have any data on the history of your exact set?

It's a beauty!!

It looks marvelous! See you in Hilliard!

Thanks guys, for the nice words. And Bob, you are too kind!

Andy, I use silicone RTV from Alumilite, HS-11.

https://www.alumilite.com/ProdDetail...th%202%20(HSII)

But you can get silicone rubber from many places. This particular version mixes 10:1 by weight, but you can get types that mix 1:1 by volume as well. The HS-II is stretches a lot and resists tearing.

Now, as for the plastic, Smooth-On makes a bewildering variety of liquid 2-part plastic products.

http://smoothon.com/liqplas.htm

I choose the Smooth-Cast 322 product, which cures to a off-white opaque color, can be tinted to any color using pigments (from Smooth-On), has a pot life of 20 minutes, and does not seem to be very moisture sensitive. They also have clear products, black products, and a wide variety of pot lives and hardness. Some types are very moisture sensitive, so read the product data sheets, and if you call Smooth-On, they can advise you on porduct choices.

The stuff is not cheap, a 1 pound ration of the Silicone RTV is about $30, and the plastic is about the same as I recall.

Wow, just wow.

Does the crt rebuild speak well for a possible 15GP22 rebuild? Haven't followed up on that lately. But, hey, this is the rarer beast!

In the year 2525....if man is still alive....if woman can survive.....


:D


Seriously, that has gotta be THE PRETTIEST TV I ave ever seen.

WOW! that is a nice TV set! Beautiful Picture too!

The rebuild of the 19VP22 DOES bode well for the rebuild of the 15GP22. Scotty at Hawkeye is probably going to make the first attempt in the next 2-3 months. Now, the bad news. There is currently no one who is willing to rebuild the CRT gun once it is removed from the 15GP22. I current hold 2 15GP22 guns which were rebuilt (new haters and cathodes). But the company who performed this work, Southwest Vacuum Products, is no longer willing to do this (long story, not going to elaborate at this moment). I am searching for a way forward which would allow more than 2 attempts to rebuild a 15GP22. There will be discussions of this at the ETF, and more here later.

Fantastic job! :thmbsp: That is a gorgeous, historic set that you've obviously done an excellent job on.

It warms the heart to see something that old and rare be brought back to life and restored to such condition. Not many people on the planet would or could do that, but the world is better off for the existence of people who do such things. One more piece of history that is preserved for at least another generation. Bravo! :thmbsp:

Way ta go, John! A classic "do it the right way" original restoration. The main chassis component-side pix sure is pretty, all orange and blue. The wiring even looks mostly new. This is the first time I've had the opportunity of viewing the underside of a professionally restored early '50s CT, I'm impressed!

The Judy Garland screen-shot has great color shading and detail. I know from experience that cameras can't convey the qualities of the direct view. Do you intend making provisions for external composite video input directly into the 1st video amp? I'd like to see some screen-shots of the DVE test dvd that most of us surely have for comparisons. Congrats again.....Tom

Tomcomm,

I did spend some time on the bench running the set from a video amplifier feeding the grid of the 1st video amp. This produced a superb picture, with no noise or hash. I resorted to this because the front end of the set was performing terribly, with all kinds of noise and interference. I eventually figured out the poor front end performance was due to 1. a bad antenna balun, and 2. a crappy el-cheapo RF modulator. Once I found and replaced these two miscreants, the performance was better than I expected. So to make my life easier, I am not going to install a baseband video input and amplifier. It is good enough.

By the way, the CBS 205 design was most likely licensed from RCA, at least in part, as the IF/video/chroma/matrix sections are virtually identical to the RCA cT100. CBS designed their own tuner, defelction, HV and LV power supply, and convergence circuitry. But the color bandwidth is full I&Q. :-)

Here is a photo I took while the set was on the bench and driven at baseband at the 1st video amplifier grid. The exposure on the photo is not very good and I had not optimized the convergence but you get the idea.

I can only imagine that working on/playing with this set would be like taking a ride in the 1903 Wright "Flyer"...Or going for a spin w/Carl Benz or Gottlieb Daimler in their 1886 cars...Are there any other working examples around that we know of ?

John,

Delighted that this long term project turned out so well. A good job, well done. I'll look forward to viewing the documentary on the tube rebuild at the ETF. See you there.

-Steve D.

Excellent work John! It gives me inspiration to get my RCA working!

That's quite the primitive looking CRT shield holder on the back. Or is it actually holding the CRT up as well?

Classicradio, The shield on the CRT serves to provide magnetic shielding and also serves to hold the CRT in place.

beautiful,movie like color. great job!!!

Great job John.

A pesky antenna balun; who would've thought.

Pete

John,

thank you very much for this long and excellent report about your CBS 205 project. This is a reading pleasure.

- Eckhard

Very impressive, that raster is beautiful! Wish I had that kind of know-how

Hi @ all!
John's restauration is a milestone. It shows what is possible and is absolutely state of the art. The colour balance is one of the best I have ever seen: thmbsp:
Congratulations Josef

John, Congratulations!
Great looking pictures on this set. The set itself is very nice looking too, what a 'Television Set' should look like. All your photos really tell of the time you spent
making it work again.
Cliff