The next big project (literally) is the restoration of my 30" Crosley TV, featuring the 30BP4 CRT. I have had this set a number of years now, and it has been lurking in the corner of my garage hiding under a big red bedspread. I had decided not to take it on until now for three reasons. First, its 30BP4 is a dud. Second, top of the cabinet is in poor condition, and will need refinishing. A skil which I do not possess, and am not likely to acquire. And third, I have never been able to find documentation for the set.

http://www.videokarma.org/attachment.php?attachmentid=173966&stc=1&d=1334514986

http://www.videokarma.org/attachment.php?attachmentid=173965&stc=1&d=1334514986

http://www.videokarma.org/attachment.php?attachmentid=173964&stc=1&d=1334514986

With the recent news of RACS in France possibly closing their doors this summer, I contacted RACS through Jerome Halphen to see if they would rebuild the tube. Alas, the word came back that either the tube would bee too big to fit in the over, or if it did fit, it would be too close to the heating elements. This news finally motivated me to do something I have been putting off for a very long time.

I have a spare 30BP4 up on a top shelf in the garage, but it tests quite weak on my trusty Beltron CRT tester. But the 30BP4 in my 30" Dumont Royal Sovereign does not test all that good either, and it makes a presentable, though not very bright, picture. So I decided the only thing to do was to pull the spare 30BP4 down and use the DuMont set to drive it and see if it was worth the effort to use it for the Crosley set.

Being a lazy guy, I really did not want to demount the CRT from the DuMont and install the spare. So I used the bottom canister from the shopvac as a test stand and put the CRT face down on the canister.

http://www.videokarma.org/attachment.php?attachmentid=173967&stc=1&d=1334514986

This worked out very nicely, and after a bit of configuring, I powered it up. Nothint. I adjusted the ion trap, still nothing. I checked the HV; a generous 17KV. So I flipped the ion trap over and after a bit more adjusting.... hot dog!

http://www.videokarma.org/attachment.php?attachmentid=173968&stc=1&d=1334514986

It may not be the brightest tube, but it is good enough. So I made the commitment to take on the Crosley. I made another attempt to find documentation for the set, checking (again) Riders and Sams with no luck. The Model # on the set is E-30 COBU. I have a marketing brochure which shows an artist line drawing of the set, with the Model # EU30COBU (or EU30COMU).

If any of you out there has any info on this set, I would appreciate hearing about it. To be continued....

Continuing... I decided to pull the sweep/power supply chassis and examine it, as it looked unusual. It turns out to be a rather unique configuration,
with separate transformers driving the sweep and HV. I also noted that the whole chassis was put together with nuts and screws, no rivets.
It also has no tags, labels, ink stamps or markings of any kind.

http://www.videokarma.org/attachment.php?attachmentid=173970&stc=1&d=1334516586

http://www.videokarma.org/attachment.php?attachmentid=173971&stc=1&d=1334516586


The TV chassis is clearly a more conventional production chassis, though some sort of a modification of what was probably a standard B&W production chassis.
It uses rivets, but once again, has no stamps or markings, other than one little paper label which proudly proclaims the chassis is union made.
All of this leads me to think I will likely not find any documentation for the set.

http://www.videokarma.org/attachment.php?attachmentid=173972&stc=1&d=1334517000

As I would be a bit reluctant to start recapping the set without a schematic to fall back on, I resolved to trace the wiring and generate a schematic.
Here is the result. The only unknown I found was one crisyp carbon comp ½ watt resistor, shown as R? on page 1, in the B+++ side of the primary of T1.
Does not look like it will be any trouble to S.A.T. a value for it.

I have reposted the two power supply schematic pages in a later post in this thread.

Next, I will generate a schematic for the TV chassis, containing the RF/IF/video/sync/V&H oscillators. To be continued....

John, this is all very interesting! I always thought that the Crosley was a rebadged Dumont. Am I to understand that this set does not share the same chassis as the Royal Sovereign? Also, very nice to see one of these sets in the flesh. I have only ever seen print ads for the Crosley, never the real thing. Do you know of any other collectors that own a 30" Crosley?

leadlike, as you may know, the Royal Sovereign came in two versions. The RA119A featured a RF HV regulated supply, a continuous tuner, and a very deluxe design (as DuMont was wont to do). The second version, (my set), the RA119B1 has a conventional click tuner, flyback, and a very pedestrian design. The Crosley design is their own. The TV chassis is very similar to some other Crolsey B&W sets of the same vintage, but the HV supply (I believe) is unique. I am really looking forward to getting it restored and see how it performs.

Zowie!!!

If it makes that kind of picture without any recapping, it should be an easy restoration. Just keep your forklift handy :)

For such a rare item, I would definitely look into having the cabinet done. There are quick/easy things that can blend minor boo-boos and improve the appearance a lot, if you don't want to invest in a total refinish.

Regards,

Phil Nelson
Phil's Old Radios
http://antiqueradio.org/index.html

Phil, The CRT was being driven by the 30" DuMont chassis (which has been recapped), not the Crosley chassis (which have not been recapped). Still, I foresee no real problems restoring the Crosley, just he usual work of replacing wax paper caps and restuffing electrolytic cans. I WILL have the cabinet refinished.

I get it.

Just looking at that giant red CRT gives me a backache.

Phil Nelson

I get it.

Just looking at that giant red CRT gives me a backache.

Phil Nelson

If it's like other Metal/Glass tubes it probably doesn't weigh all that much but I've never handled one bigger than 16"

The 30" tubes don't weigh very much. I remember KX250rider made a post about handling a Royal Sovereign as well as the crt, and he noted how surprisingly light the metal-glass crt is. Certainly the 16" one I handled out of my Zenith seemed totally featherweight compared to an all glass one.

John, I wasn't aware that Dumont made a "cheaper" version of their Royal Sovereign sets. Kind of disappoints me since I only thought they dropped continuous tuners and robust build quality after Emerson took them over.

As an aside on 30BP4s-so few are found today, and even fewer that test good. Did they have a tendency to deplete their cathodes faster than say, a 12" tube did? They certainly shared the same type of gun, but the 30" had vastly more screen area to light up than any of the other B&W crts ever did.

The 30" tube is big, awkward and scary to handle, but not all that heavy. The tube was stored above my head on a shelf in the garage. The scary part was standing atop a 2-step footladder, embracing the bell of the tube, lifting it to point the neck of the tube past my head and over one sholder, and wobbling back down the 2 steps. Whew!

If you look at the photo of the CRT behind the DuMont, you can see the cheaper version chassis. Very conventional.

As for the life expectancy of the 30BP4, I just don't have any data on the subject. I would speculate that not a lot of sets were made using the 30BP4. Seems like DuMont only produced that tube for 2 year(?). Maybe longer for renewal reasons. Or they may have offered rebuild services. The urban legend is that all the metal cone CRTs had a higher failure rate than the all glass CRTs. Seems probable, but I have not seen any reports or articles on the subject.

Hi John... The "bourbon legend" on the 30BP4 is derived from the 15GP22. And, from what I've heard from those blessed (cursed?) to have had to work with such is almost universal based upon being a metal/glass hybrid. (What was the original hybrid? The mule!)

One thing about the Crosley, have you ever though about trying the IUE local(s) in the Cincinatti area or nearby to other Crosley plants? Perhaps a retiree may be a source of schematcs or at least info...

INteresting idea.... but from down here in Florida, I would not have a clue how to deal with the IUE in Cincinatti.

I have pulled the TV chassis. It appears to be a modified version of their 21" model in Sams 186-3. Going through the video IF, so far it is identical. But I ams sure I will find some differences, and will end up drawing a schematic, as it would be too hard to try and mark-up the Sams to document the changes.

Hi John... The "bourbon legend" on the 30BP4 is derived from the 15GP22. And, from what I've heard from those blessed (cursed?) to have had to work with such is almost universal based upon being a metal/glass hybrid.

But the 15GP22 has an additional "weak spots" that the 30BP4 does not have... the welded flange on the 15GP22 appears to be the major source of leaks. IMHO, one of the problems inherent in the metal cone tubes is the limited getter flash area, as the metal cone allows only the use of getters in the neck rather than the funnel. Much less getter flash area is obtained.

jr

Wow...This is going to be an interesting restoration project John, will be following this thread for sure! :yes:
The largest black and white CRT I've seen is 25 inches in diameter. I have a couple of TVs that use them and both give a very nice picture.
Cheers
Glen.

The next biggest B&W CRT was the 27"... I think there were at least 4 versions made by various CRT makers.

Nice job on those schematics John. That must have taken a lot of time and patients to trace and draw. Good Job!

Thanks Bob. A great deal of my career as an electrical engineer was spent using various drawing editors to generate schematics and PCB layouts and fun simulations, so this was familiar territory. The program I used was from a PCB fabrication company, ExpressPCB (http://www.expresspcb.com/). They supply free software to drew schematics and lay out 2-sided PC boards. The software runs on a PC, or in my case , on a MAC running PC emulation software. I used this software a few years back to design my 'personal color wheel viewer' that I displayed at the ETF.

Steve McVoy used the same software to generate the schematic of Nick's prototype color TV, and Steve was kind enough to let me use his library of components he had created (tubes etc). This made my job a bit easier.

The software is easy to learn, and easy to use, so if any of you want to draw a schematic and/or lay out a PC board, check them out. They have a pretty extensive library of pre mace components, both analog and digital, and it is easy to create custom symbols and shapes in the schematic editor.

PS I noticed a bunch of errors in the reference designators on my posted schematic. Fixed 'em, will update them the next time I make my next update.

Hi John,

Wow: this is an amazing set. Looks like you are going to have lots of fun with this one. I will stay tuned for more.

I reviewed your drawings and I spotted one thing I cannot figure out. It looks like you specified for V10 a 6BQ6 for the vertical output. The control grid has a 500ufd/ 50volt capacitor on the control grid I cannot make sense of. The 500ufd would have to me been more appropriate as the cathode resistor bypass capacitor.

Terry

John, your reference to the Express PCB Schematic software piqued my interest. I downloaded it and it runs on my Linux desktop too using "Wine".

One thing I did notice is that it lacks Vacuum Tube symbols. Did you custom create those symbols or is there a library I can import?

Thanks

Carl

Terry, Oops, my bad. Once you make a mistake, it can be hard to see it. Yes, that cap should be on the cathode. :-)

Carl, send me an email address and I will send you the custom library with conponents tha Steve McVoy and I have created.

This is nothing short of exciting. I've never seen a 30" B/W CRT set in my life.

I've only seen one 27" B/W, and it was a Magnavox, and was weak, even with a brightner.

I've only seen one 27" B/W, and it was a Magnavox, and was weak, even with a brightner.
Every 27" I ever seen was flat as a pancake, as well as every 24" (all Maggies).

Every 27" I ever seen was flat as a pancake, as well as every 24" (all Maggies).

I think it has to have something to do with the size, painting a bigger canvas with the same sized brush and all plus higher 2nd anode voltage pushing it harder.

leadlike, as you may know, the Royal Sovereign came in two versions. The RA119A featured a RF HV regulated supply, a continuous tuner, and a very deluxe design (as DuMont was wont to do). The second version, (my set), the RA119B1 has a conventional click tuner, flyback, and a very pedestrian design. The Crosley design is their own. The TV chassis is very similar to some other Crolsey B&W sets of the same vintage, but the HV supply (I believe) is unique. I am really looking forward to getting it restored and see how it performs.

John, is that the set I sold you many years ago? I'm refering the low-end chassis model. The same guy I bought my set from, also had a Crosley set like you're showing. That set had a 1952 model Admiral 27" chassis in it. The original chassis had a burned up flyback in it, and was scrapped.:thumbsdn:

The next biggest B&W CRT was the 27"... I think there were at least 4 versions made by various CRT makers.

IIRC, Admiral used the magnetic focused 27" glass CRT's. RCA was famous for the 27" metal cone CRT. Magnavox used the electrostatic focused glass CRT's, to the mid-60's. The last one being the solid state B&W chassis. All were 90 degree deflection.

...the RA119B1 has a conventional click tuner, flyback, and a very pedestrian design.

John, did you ever trace out the schematic for the RA119B1 or ever find any service information on it? Is it similar to any other DuMont you've come across? I still haven't attempted restoring either the RA119A or the RA119B1 that I still have in storage.

Also, does anyone have an idea of how many of these 30-inch sets still exist? You and I have the only RA119B1 sets that I know of, and you have the only Crosley I've heard of.

Well, wiscojim, if you are Dave Nash, the answer is yes. Never did find any documentation for the set, but recapped it anyway. Now that I am drawing a schematic for the Crosley, I probably should do the same for the 30" DuMont. When/if I do, I will get you a copy. I have heard of a handful of 30" DuMonts. Steve McVoys ETF website shows 8 in his database. Probably a few more out there, but not a lot more.

Well, wiscojim, if you are Dave Nash, the answer is yes. Never did find any documentation for the set, but recapped it anyway. Now that I am drawing a schematic for the Crosley, I probably should do the same for the 30" DuMont. When/if I do, I will get you a copy. I have heard of a handful of 30" DuMonts. Steve McVoys ETF website shows 8 in his database. Probably a few more out there, but not a lot more.

John! I'm Dave Nash, AKA known as dieseljeep on this forum and also A-K. My beloved Diesel Jeep Liberty is in Jeep heaven now. Rust in peace.

Well then Dave, I am kinda confused. Who is wiscojim?

wiscojim is the guy who didn't sell you RA119B1 he has--and dieseljeep is the guy who sold you the one he had. :)

I'm lost, lol.

It all makes sense to me, but then again I've met wiscojim.

Wiscojim is Jim Menning from Appleton Wisconsin.

John, I'm really looking forward to seeing the Crosley when I come tommorrow.
Looks exciting....
Bill Cahill
I think I should have kept the 24" tv....

Bill, we will have a fun day.

wiscojim and deseljeep, its all sorted. And nice to put a few more names with aliases.

Work progressing on drawing the schematic for the Crosley TV chassis.....

Thanks guys, for sorting it out in my absence. I don't come here every day, and forgot to subscribe to the thread to receive the email notifications of new posts.

Yes, John, if you do ever get around to documenting the B1, I sure would appreciate copies of anything you come up with.

Wiscojim (Jim Menning from Appleton, WI)

I know this is a Crosley thread but as far as the DuMont RS goes I remember seeing something like a service bulletin from DuMont regarding a CRT retrofit for the 30BP4. It was supposed to be a kit of parts to install a "new" square tube in place of the round tube, almost like they were saying the 30BP4 is a dud and we ain't making any more of them.

Anyone heard of such a thing? Are there any more 30BP4 based sets?

I've got a question. The weak point on these large 19 to 30" DuMont CRTs are them going to air past the metal to glass joints, right?

What's to stop you from masking off the joints and applying a clear silicone top seal to eliminate future leaks? Or, another compound?:smoke:

I have one of the DuMont RA-119As, BTW.

Cosmetically, it's superb. In fact, it's the best set in my collection in terms of origional condition. It belonged to a VP of Engineering of Sprague Capacitors in the 50's.

I have a 27RP4 in new condition with great emissions. I'm thinking of using that instead of the 30. Or, maybe the guts of a modern LCD or plasma tv screen for video, sort of an old/new hybrid.

Didn't mean to hijack the thread. I now return you to our regularly scheduled program...:smoke:

I know this is a Crosley thread but as far as the DuMont RS goes I remember seeing something like a service bulletin from DuMont regarding a CRT retrofit for the 30BP4. It was supposed to be a kit of parts to install a "new" square tube in place of the round tube, almost like they were saying the 30BP4 is a dud and we ain't making any more of them.

Anyone heard of such a thing? Are there any more 30BP4 based sets?

Yeah, I've heard of the 27" Retrofit. From what I've read, it comprised a new 27" CRT, a new mask, and no doubt some parts to cut back on the anode voltage to the CRT, etc.:smoke:

After many hours of toil, here are the completed schematic pages for the Crosley. Now I can begin the electrical restoration with some confidence.

First the 2 pages for the power supply chassis, then I will post the 4 pages for the TV chassis.

http://www.videokarma.org/attachment.php?attachmentid=174142&d=1335570054

http://www.videokarma.org/attachment.php?attachmentid=174143&d=1335570054

And here are the 4 pages for the Crosley TV chassis. Enjoy!

http://www.videokarma.org/attachment.php?attachmentid=174144&d=1335570544

http://www.videokarma.org/attachment.php?attachmentid=174145&d=1335570544

http://www.videokarma.org/attachment.php?attachmentid=174146&d=1335570544

http://www.videokarma.org/attachment.php?attachmentid=174147&d=1335570544

John, that thing is a beast! Large quantities of tubes that are power hungry. I imagine it draws at least as much as a tube-type color set?

Nice job. Let the work begin...

From what I've read about it, I don't think that silicone or any "sealer in a tube" would stop high vacuum leaks: the force involved is tremendous. Others have tried to seal I believe using a special glass melted at the joint, probably not possible in a home workshop.

From what I've read about it, I don't think that silicone or any "sealer in a tube" would stop high vacuum leaks: the force involved is tremendous. Others have tried to seal I believe using a special glass melted at the joint, probably not possible in a home workshop.

I'm not so sure about that...

I mean, consider a layer of clear silicone, say even 1/16 to 1/8", on top of an intact metal to glass seam of a CRT. An intact seam. It would seem to me that silicone, which is pretty dense, would have a tough time entering a small fissure or pinhole that would arise in such a joint.

We're talking about a vacuum here. How is hardened silicone going to creep INTO a joint under those conditions? Again, I'm talking about a preventative measure here.:smoke:

Prolly worth a shot...What have you got to lose ? If it saves a truly Unobtainuim CRT, then, it'll be worth the effort.

The problem you will have is that the silicone doesn't adhere nearly well enough to prevent a vacuum leak, the air would just creep under the sillycone and still get in. That's why I think the nickel plating that Bob has done will work, because it's actually a hard coating on the metal ring, as frit is to the glass bell.

I dunno....silicone bonds to both glass and metal very well. If you prep the surface with some lacquer thinner or alcohol it should bond well.

Also, silicone flexes very well, and stands up to high temperatures.:smoke:

If such an easy solution worked, don't you think it would have been tried already?

If I had a dog in this fight, I'd try this stuff:

http://www.pchemlabs.com/product.asp?pid=2629

If I had a dog in this fight, I'd try this stuff:

http://www.pchemlabs.com/product.asp?pid=2629

Yeah, I know about that stuff. Do you think a CRT gets THAT hot? Regular silicone is pretty good at standing up to temperature, I believe...:smoke:

If such an easy solution worked, don't you think it would have been tried already?

Has anybody tried it?:smoke:

The ones to ask would be those involved with the early television museum project of trying to seal leaking CRTs. I don't think they would have gone to all the trouble with frit glass and such if an easier method would work.

Has anybody tried it?:smoke:

It won't even keep the oil inside my VW engine, there's no way it's gonna keep air out of a CRT! lol

After a glorious time at the ETF convention, its back home and back to work on the Crosley.

First up is the sweep/power supply chassis. A straightforward recap job. Three of the four electrolytic cans were restuffed. The fourth, a single section 500uF/50V was replaced with an axial electrolytic under the chassis, leaving the old can unconnected but in place for cosmetics.

http://www.videokarma.org/attachment.php?attachmentid=174358&d=1336779880

Now on to the main TV chassis......

I thought the Dumont Sovereign was the only 30" set back then just goes to show what I don't know.

I am guessing that the DuMont 30" set was the only one produced in any quantity. Dumont made two production versions of the 30" set.

As I have not been able to find any documentation published on the Crosley, and the Sweep/Power Supply chassis is put together with nuts and bolts (no rivets), I think the Crosley was produced in very small quantities.

I'd love to have a set with no rivets.

that is i think the first one i have ever seen ,sure is interesting set.

The recap of the main TV chassis is complete. The electrolytic cans have been restuffed. All the silver micas were replaced to improve reliability. A goodly number of off value resistors were replaced.

http://www.videokarma.org/attachment.php?attachmentid=174441&d=1337286425

All of the AC wiring needs to be replaced, and tubes still have to be tested. And the little UHF converter chassis needs to be recapped. And when all that is done, I still have to swap out the CRT. So still some work to do.....

Nice work, John.

Nice work, John.

Yeah-This brings up a point-Do WE do a better job re-doing this old stuff than when it was originally made ? I know in certain cases, we have better components-eg capacitors-now than they did "Back then", but I'd argue that we put an extra value of "Love" into these old sets that wasn't there when they were made.

Yeah-This brings up a point-Do WE do a better job re-doing this old stuff than when it was originally made ? I know in certain cases, we have better components-eg capacitors-now than they did "Back then", but I'd argue that we put an extra value of "Love" into these old sets that wasn't there when they were made.

No doubt about that. When restoring or even simply repairing a set, we have the luxury of taking as much time as we want to make sure that things are done "right". This simply wasn't possible for production workers on an assembly line.

We can also choose to use better quality parts than the original manufacturer did. This covers cases where either the technology has vastly improved (capacitors), or where the original design cut corners to save money (higher wattage resistors to replace ones which have overheated and drifted).

In addition we have some history and knowledge about the pros and cons of the TV and can try to correct some issues.

Carl

Nice work John! Wish I could have spent a couple days with you last week. Has the cabinet came back from the refinisher?

Bob, I am still waiting on the Admiral 21" color and Airline 7" TV cabinets to come back.

Chuck A will be by this weekend, and I plan to try and swap out the Crosley CRT and power it up for the first time.

So exciting watching a 60 year old piece of electronics coming back to life after a long long slumber!

The first plug-in after capacitor replacements is always a feeling of anticipation to me.

Bob, I am still waiting on the Admiral 21" color and Airline 7" TV cabinets to come back.

Chuck A will be by this weekend, and I plan to try and swap out the Crosley CRT and power it up for the first time.

PUH-LEEZE Be Careful !! You guys really oughta have me down there, wringin' my hands & worryin' for you...

As to weather we improve things or not.

I feel there are several factors where we can "improve" things when restoring/repairing these old sets.

Higher quality components, for Korean War Era 1950-1953 sets, wartime restrictions caused some components most notably resistors to be of lower quality, today's resistors are of MUCH higher quality if we chose good ones.

Capacitor tech has improved greatly in lets say the last 80 years (going back to 20-30's AC radios here) not only are they MUCH more stable and reliable and also take up MUCH less room, making subsequent repairs easier because of the extra space.

TSB's In many cases we have access to not only schematics through Sams and Riders but we also have Technical Service Bulletins (to use a GM term) from the maker to implement production changes and improvements.

Enhancements, we also have the opportunity to add things to earlier or less expensive sets that where never designed in them in the first place DC restoration is an example, and possibly extending video bandwidth on sets such as the post 1954 RCA B&W ones that had a 2.8 mHz bandwidth. Or even crazier stuff like direct AV drive or even component inputs!

Oh and lets not forget the biggest thing REVERSING BAD and BUTCHERED repairs!

All in all I think we make these wonderful sets even better.

Matt

Yeah-This brings up a point-Do WE do a better job re-doing this old stuff than when it was originally made ? I know in certain cases, we have better components-eg capacitors-now than they did "Back then", but I'd argue that we put an extra value of "Love" into these old sets that wasn't there when they were made.

The old sets we love to work on and devote much time to were manufactured on an assembly line, so the faster they were turned out the more money the mfgr. made. I doubt the old sets were assembled, tested and boxed in more than a few hours--may be far less, so there was no love for these sets at the factory, only for the bottom line.

The Cliff, who spent the weekend repairing and now listening to a 70 year old Philco console radio that was my dad's. It looks like a friendly fireplace in a dark room.

Cliff,

Do I see PreWar FM on that set?

Matt

The old sets we love to work on and devote much time to were manufactured on an assembly line, so the faster they were turned out the more money the mfgr. made. I doubt the old sets were assembled, tested and boxed in more than a few hours--may be far less, so there was no love for these sets at the factory, only for the bottom line.

I think you have to separate the management from the the rest of the team before making such a broad-brush comment about ALL of us production workers. Managers cranked the production numbers as high as the workers could bear sometimes, but there were, and still are people who are proud to put their name on their work. Don't you take pride in your work? When I was a biomedical mfg. tech, I had to get it right, lest someone cash in their chips while being monitored or defibrillated by something I said was okay to ship.

Even some company founders had a customer-comes-first attitude. Find a copy of A First-Class Job about the life of Frank Murphy (of Murphy Radio in the U.K.) and see why his company's products are so revered among collectors. Not every manager in an expensive suit bowed to stockholder or Wall Street pressure, and tin-plate ladder-climbers often had strong union pushback when their blind ambition made life unbearable for the line workers.

And as far as better parts available, I feel the poly-film-dielectric capacitor was a great replacement for the paper-in-oil caps of the early 20th century. Precise resistors are readily available and cheap nowadays, but the ones available back then usually lasted a long time, and I prefer the look of a shiny A-B or Ohmite to those pale, ugly dog-bones you get off the boat.

And noone has been able to explain on here why I need low-ESR caps when the original versions perform just fine. Just sayin'...

Just to follow up on the idea of sealing a CRT leak with caulk --

NO polymeric material is a good long term vacuum seal. Every plastic or rubbery material known has a finite permeability to gasses, including the constituents of air like nitrogen, oxygen, and water vapor. You can't even keep humidity out of enclosure with a polymeric mareial, let alone keep a high vacuum over time.

For a good vacuum seal, you need to use metal, glass, or ceramic. There is a reason why you never see any other materials used on something that needs to hold a high vacuum over extended periods of time.

Just to follow up on the idea of sealing a CRT leak with caulk --

NO polymeric material is a good long term vacuum seal. Every plastic or rubbery material known has a finite permeability to gasses, including the constituents of air like nitrogen, oxygen, and water vapor. You can't even keep humidity out of enclosure with a polymeric mareial, let alone keep a high vacuum over time.

For a good vacuum seal, you need to use metal, glass, or ceramic. There is a reason why you never see any other materials used on something that needs to hold a high vacuum over extended periods of time.

Yeah, that was my brain-child. I thought a high grade clear silicone bead was air tight, and that it would be held in place, or not disturbed, by vacuum pressure drawing it tight to the seam, if and when a leak did transpire.

I know about their shortcomings in the automotive world, but that involves OUTWARD pressure, not inward.:smoke:

When I restored my RCA CT-100, I applied a product called Vacseal (http://www.2spi.com/catalog/vac/vacleak.shtml) to the 15GP22 perimeter joint, thinking that it might help and it couldn't hurt. I believe John and Bob G. may also have experimented with applying Vacseal and curing in a heat box around that time.

They have done a lot of investigation since that time, and I believe the current thinking is, as Tom says, that you need something like glass or metal. The only proven method is frit glass. The RACS company in France did a frit glass seal on a 15GP22 some time ago, and the last I heard, it was still holding up at the ETF. My 15GP22s are still holding up, too, but that proves nothing, since they didn't leak before I applied the Vacseal.

Phil Nelson

I'm with Bob when it comes to the 15G. If you have one with good emissions and getters, it's probably best to leave it alone. After all, it held vacuum for the last 58 years without any help so why fix what isn't broken. If on the other hand you need a rebuild, the full protocal of leak sealing ought to be applied whether it was still under vacuum or not. As proven by the rebuild attempt of John's under vacuum tube, leaks can pop up even if you assume the thing was good before. It still took a full 30 days for John's tube to become gassy, so it may start out good and deteriorate. I think in the future, 15G owners will likely opt to have the tube treated with frit regardless if it was still under vacuum or not.

Chuck A was up over the weekend, so we decided to give the Crosley a try. Saturday evening we swapped out the dud 30BP4 for the spare I had. After a lot of adjusting and hooking things up, we connected the variac and brought it up. Nice aucio, but that was all. No high voltage. Kind of a let down. We called it quits for the evening.

Next morning we put the 2 chassis, yoke/focus coil assembly and speaker on the work bench and hooked it all up. First discovery was a blown fuse (which I had tested good earlier). We replaced it and began looking for high voltage.

But here is where I made a really stupid error. Using my B&K HV probe which is a 1000:1 divider, I misread the meter. It was showing voltages (at various times) between 1.1 and 2.0 volts. I was calling this 11K - 20K volts, and we spent the whole day trying to figure out why the high voltage was low and unstable. It would go from 15-16KV down to 11KV or less as thing warmed up. Swapping tubes, checking wiring, freeze spray, nothing we tried was any use.

Chuck A departed back down to south Florida in the morning. Later that afternoon I sat down to have another go at it. Apparently my brain was actually working, and I realized that the meter had been telling us that there was ONLY 1.1-2.0 KV! And yet, using a screwdriver, one could get a big purple arc from the plate of the first 1B3 in the HV doubler. I immediately realized that this meant the rectifiers were not working, probably because the filaments were not being lit. The tubes derrive their filament voltage from the sweep flyback, not the HV flyback. I put two solid state 1B3 replacements in and go 28KV. Hooray!

A check of the bias on the two 6BG6s driving the sweep flyback revealed no screen grid bias. The 3K ohm 10W bias resistor (which had ohmed as good earlier) was open. With a replacement installed and the 1B3s back in, I got a robust 20KV. After things warmed up, it settled at 18KV plus.

I tested all the tubes on the TV chassis, and found none to be bad. I reinstalled everything back in the cabinet, and after some adjusting of the yoke and focus coil and centering lever, gat a very presentable picture. I actually looks much better than these photos indicate.

http://www.videokarma.org/attachment.php?attachmentid=174518&stc=1&d=1337816915

http://www.videokarma.org/attachment.php?attachmentid=174521&stc=1&d=1337817036

http://www.videokarma.org/attachment.php?attachmentid=174520&stc=1&d=1337816915

This CRT works even better than I hoped. Plenty of brightness and contrast. Next time Chuck A is up, we will do setup on the V&H size and lin, and play with the pincushion magnets.:banana:

I am jealous.....Nice Set!!

Thats one handsome TV set! I've never seen a round screen 30 incher!

I'm in love...Hats off to you guys !

Wow, that is an extremely impressive set! Way to go!

Dave

Ditto I'm impressed.

Kinda sad, really...How many of those Dumont/Crosley sets are still around after 60 yrs, & how many still WORK ? And now that Scotty/Hawkeye has thrown in the towel, there will likely NEVER be anymore ever rescued...Says something pretty damning, to me, anyway, that w/all our grand & glorious 2012 technology, we CAN'T bring an obsolete television back to life....Well, except for a small group of Mad Monks, maybe....(grin)

That looks great, John.

Kinda sad, really...How many of those Dumont/Crosley sets are still around after 60 yrs, & how many still WORK ? And now that Scotty/Hawkeye has thrown in the towel, there will likely NEVER be anymore ever rescued...Says something pretty damning, to me, anyway, that w/all our grand & glorious 2012 technology, we CAN'T bring an obsolete television back to life....Well, except for a small group of Mad Monks, maybe....(grin)

+1 and I'm thinking maybe this is the only working one, with a picture anyway. Could be wrong. Nice work all around. Great to see one of these behemoths working.

I am aware of at least 2 or 3 working DuMont 30" sets (I have one), and there are probably a few more. The ETF website shows 8 sets known, not sure how many are working.

Yeah, I shoulda known. Sorry, John.

My friends uncle owned a TV shop that closed in the 90's. he has one of those 30" CRT's at his house. if I ever get over there, I might try to buy it in case someone here needs one.

Very nice, John! And, you only had to take it apart twice!! :D:drool:

Seriously, nice job on a very nice set. I saw the set in your garage when I came. I fell in love with it then....
Bill Cahill

I am aware of at least 2 or 3 working DuMont 30" sets (I have one), and there are probably a few more. The ETF website shows 8 sets known, not sure how many are working.

Now that you have two working 30 inch sets you should put a 72 inch color wheel on at least one of them. :banana:

Cliff

I have these questions:

What are the dimensions of that cabinet?

and

How much do you think it weighs?

I love the styling of the set. I'm thrilled it plays well!

Bruce

Ha ha! You so funny! :-) Still, I have fantasies of putting a color wheel on the DuMont
Westminster 20" 'pop up CRT' set. But probably not. :0)

Isn't there a picture around that does show a color wheel in front of a 30-inch Dumont TV? That wheel assembly was more like ten feet around if I remember right.

Bottom of this page:

http://www.earlytelevision.org/cbs_color_system.html

These were the LARGEST B/W CRTs ever made, right ? I mean, there weren't even any larger ones ever made even for experimental/industrial purposes ? And IIRC, "Their Reach kinda exceeded their Grasp" w/these puppies, they had problems w/Ion burn & other things.

What a wonderful set. You don't really appreciate the scale of these 30" TVs until you see one in person or see a photo like the color wheel shot, with a human standing next to the cabinet.

Phil Nelson

I saw that set in person. It's neat. I was really impressed with the hv supply chassis.
The cabinet styling, I think Crosley outdid themselves. It's beautiful.
Bill Cahill

Atta Boy, John. Nice work.:smoke:

John did you ever see this?

http://4.bp.blogspot.com/-LpuMLz42wXQ/Ta9wxctokfI/AAAAAAAAAwE/QFVoipHHxag/s1600/Crosley+TV.jpg

That set has UHF? I thought these 30-inch sets were from 1950-51. Or, was Crosley that far ahead of its time?

Thank you for posting that interesting ad, David.

Bruce; The cabinet measures about 50" W X 62" H X 24" D. I don't have a good estimate for the weight. I put casters on the set, so it is easy to move around.

Dave, I do have a copy of that Crosley flyer, thanks. The flyer calls out two models:
EU 30COBU (blonde)
Eu 30COMU (mahogany)

There were two paper labels in my set one for model is E-30 COBU, one for E-30 COMU. None of these model numbers shows up in any Sams Riders or other set indexes.

The set has a UHF converter built in. I see some original Crosley tubes with 1952 date codes, though most of the tubes have been changed out.