My "new" 1954 CTC2B 21CT55 21" roundie

[walterbeers]

I've used capacitors from Capacitor World for several different sets, and never had a problem with them. Once in a while when replacing large long wax caps, the leads don't reach so I have to solder some extra lead wire onto it, but that is to be expected since the capacitors today are so much smaller in size. I'm sure I will be ordering more from them as I continue to restore old retro, unique, and antique TVs, and radios.

[etype2]

Congratulations on bringing the RCA 21-CT-55 back to life.

[roundscreen]

Originally Posted by ohohyodafarted

Nice Job Walter,

RE: your issue with contrast and brightness. My CT55 does the same thing. I have never been able to figure out what causes this issue. Someone told me that the HV section is probably just not capable of supplying enough current when you drive the tube real hard. My set has a NOS flyback so I know that the flyback is not the issue.

I would bet that if you look at the HV level when you drive the tube real hard to the point where the picture pulls in, you will see the HV droping. I can drive mine so hard that I can cause the picture to almost fade away. My 21AX was rebuilt by Hawkey before they closed so it has very strong emission from the guns which easily can overwhelm the HV section.

I also have another issue that I never was able to track down. It takes about 15 minutes for the convergence to stabilize. I thought the problem was a leaky capacitor in the convergence chassis, but after rebuilding it, I still had the issue. I can speed up the stabilization by turning the brightness up real far and forcing the picture to shrink in and go out of focus. I don't understand the relationship between these issues, but after the set warms up it has a great picture.

The RCA service manual purity adjustment step 5 states that the repair man should set the contrast fully counterclockwise and set the brightness control for maximum brightness with out blooming. This would tell you that it normal that the set can bloom with the brightness turned up to high. Also when you do convergence on any tube color set, It is best to run the set for twenty minutes before you start the convergence procedure. So really, Your set's are working fine. I have a ctc 16 that has to be on for a few minutes before the convergence stabilizes. I changed the convergence board with a known good one And it still has to warm up, So it must be the CRT. Walter beers. That is a really good picture on your set.

[walterbeers]

Thanks for the compliment "round screen". Well I got another NOS Horizontal output and a NOS damper tube, and the set hardly pulls in at all unless I crank up the brightness way too high. Cathode current of the 6CB5 I think is a little high, 223 ma or so, and I tried adjusting the horizontal efficiency (linearity) coil and that is the minimum current I can get it adjusted to. Picture even looks a little better with the tubes in there. High voltage is running around 22 to 23KV, but it will not adjust up to 25KV as per the Sams. I'm not sure though if my probe though is completely accurate. Actually I haven't even touched the dynamic convergence yet, and it looks fairly close. I just did the center convergence and purity, and purity is still off a bit, but will make final and closer adjustments when I get the cabinet touched up or refinished, and the chassis back into the set.

[walterbeers]

I still have the chassis on top of the cabinet, and attempted a rough dynamic convergence. I also replaced the 6SN7 tube, had to readjust the horizontal frequency coil to get the picture to lock and now I have the cathode current down to around 208 ma. Apparently the 6SN7 was a bit weak although the tube tested good. Here is a picture of my rough dynamic convergence attempt. It's not perfect, but close.

[Steve D.]

Walter,

I'd say that's pretty good convergence. I wouldn't knock myself out doing much more set up until the chassis is back in the cabinet and the set is sitting close to its final resting place in your home. Of course, after convergence, purity and screen adjustments would be about the last items on the list imo.

-Steve D.

[walterbeers]

Here is the latest, as of Dec. 27th, 2015. I have been working on refinishing the cabinet, and have it looking pretty good. (I am definitely a novice as a cabinet re finisher). I used a Minwax mahogany gel stain after a hefty rubdown with lacquer thinner on the sides and front of the cabinet. For the top I used a varnish/paint remover to get all of the old finish off down to the bare wood, sanded it with a power finish sander, then applied the gel stain. Then I gave it 2 coats of Minwax semi-gloss fast drying polyurethane. It has a few (feel-able) dust speckles in it as I had to do it in my finished basement shop area, since I don't have a dust controlled environment. I took the escutcheon off that holds the safety glass in, and cleaned off the black goo that was between the glass and the mask around the CRT. I don't really know what the goo was from, as I didn't see any kind of gasket or glue substance. The clips that held the escutcheon in were a challenge to get to, as I chose not to remove the CRT. I tried about everything to polish the escutcheon, but nothing worked, so I ended up spraying it with a brass colored spray paint. It may not be perfect or exactly original, but I gave it my best attempt. Here are some pictures of the cabinet. The chassis is set back into the cabinet, but it's not re-connected yet, and final adjustments have not been made.

PS: FOR THOSE INTERESTED, I am NOT intending to sell this set (or my CTC9) as I intend to cherish and keep it for all of the hard work I have put into it.

[Electronic M]

From owning a CTC-4 with the same CRT mask assembly I can tell you the following: The black goo was once a rubber gasket. They degrade differently with each sets' unique storage conditions (mine was partially melted partially intact/rotted dry/gummy). That brass bezel is best polished with Brasso and an old (not going to be used on you again) toothbrush....Vigorously brushing while the Brasso is wet. Afterwords you will need to run steel wool or scotch-brite up and down the length of the strip to restore the "brushed" finish to the metal....The brass on my CTC-4 was nearly black.

[ohohyodafarted]

I am not a fan of Minwax Gel Stain. It has a tendency to cover the character of the natural grain. It can be put on too heavily and become more like paint than a true stain. I only used the Minwax gel stain once and I deplored the results so much so, that I stripped it off and started over. Apparently it is a combination of some sort of varnish and stain.

I prefer any brand of liquid OIL stain directly against the bare wood which has already been grain filled.

For finish coat, I have been using Sherwood Pre-catalized lacquer from Sherwin Williams. It is a true commercial/industrial type coating. It's available in 4 levels of sheen from gloss to a dull mat. Comes in Gallons and 5 gallon sizes. Link below will take you to a SW Pdf of the product.

http://www.paintdocs.com/docs/webPDF...&prodno=T77C35

I no longer use "varnish" for anything except when I re-finish hardwood floors.

You will need compressed air spray equipment to spray the Pre-cat. Since I started using the Sherwood Pre-cat, I have completely abandoned all other finishing lacquers and varnishes. And I very rarely use shellac any more because it spoils and always has to be made up fresh. The Sherwood Pre-cat also has a shelf life of only 6 months after the catalyst is added. However, you can ask the people at the Sherwin Williams store to give you the UN-catylized components and mix small batches when you are ready to do some spraying. That way you add catalyst to only enough to do the job at hand, and keep the UN-catalized material on the shelf for future use.

The Sherwood Pre-cat lacquer sets up in about 15 minutes. It is very easy to spray, more so than even conventional nitro-cellulose, or acrylic lacquer. Even an amateur like me can get professional results that look as good as if it came from a professional furniture factory.

I start by wiping down the cabinet with lacquer thinner. If the old finish is not too terrible, and I think it can be salvaged without an entire striping, I proceed as follows. After the wipe down with lacquer thinner, I locate any scratches that need touching up with stain. After staining the defects (where necessary) I take come Sherwood Pre-cat, and using an appropriate artists brush I paint on several coats of lacquer on the scratches to seal the wood where the old lacquer was scratched off. 24 hours later I wet sand with 220 to level the lacquer in the areas where I did the touch up. Then I lightly power sand the entire cabinet with 180 to scuff up the surface for good adhesion of the new finish. Wipe down the cabinet after sanding with an automotive type "pre-cleaner" to make sure all the old wax and silicone's are removed so you don't get "fish eyes' when you spray.

Then I spray 2 coats of Sherwood Pre-cat. 24 hours later I wet sand again to flatten out any dust particles that landed in the wet lacquer. And finally I give it one last coat of Sherwood Pre-cat. The results will look like it just came from the factory.

[Kevin Kuehn]

Is that SW Pre-cat lacquer still dissoluble by lacquer thinner once it's fully cured, so you can blend in repairs like traditional nitrocellulose? I'm thinking not, but I've never used the stuff. However we may not have many choices in the near future, other than to use some non dissoluble finish.

[Titan1a]

Walter, it looks great. Now for the picture! You do good work.

[ohohyodafarted]

Originally Posted by Kevin Kuehn

Is that SW Pre-cat lacquer still dissoluble by lacquer thinner once it's fully cured, so you can blend in repairs like traditional nitrocellulose? I'm thinking not, but I've never used the stuff. However we may not have many choices in the near future, other than to use some non dissoluble finish.

Kevin,
I can tell you the pre-cat Sherwin Williams lacquer I use is Nitro-Cellulose based. They also make a pre-cat Acrylic lacquer for applications where you can not tollerate the fact that NC turns yellowish over the years. The acrylic pre-cat is useful for light blonde finishes that must not yellow over time.

The claim is that pre-cat is more durable than a conventional NC lacquer. I have read that if you re-coat during the time frame when the pre-cat is still not completely cured, the re-coat "melts" into the existing finish. I did read a thread where the poster spoke to SW tech support people and they assured the poster that regardless of how long the pre-cat had cured, re-coats would adhere into the existing finish.

I read another post by a furniture re-finisher who said he uses pre-cat lacquer all the time and it is easily "repaired" unlike polyurethane varnish.

Other sources say that pre-cat must be sanded prior to a repair job to make the new repair adhere mechanically. This infers that the cured pre-cat can not be dissolved by the new lacquer.

That said I can say that the Nitro Cellulose component of the pre-cat product should always be lacquer thinner soluble regardless of how old the pre-cat finish is. I just can't quantify for you how easily it will dissolve. I would suspect it would dissolve very much like 50 year old conventional NC lacquer that was applied to our tv sets back in the 60's

From what I understand, conventional NC lacquer dries when the thinner evaporates. Pre-cat has additional components that "cross-link" making the product more durable. Still the bulk of the product is nitro cellulose and should be soluble in lacquer thinner.

Varnish does not "dry" it "cures" through cross linking. That is why old varnish is notoriously difficult to soften and re-coat. Usually you have to sand varnish to re-coat to get mechanical adhesion. Or else you strip old varnish and refinish.

Post-catalyzed lacquers are a bit of a different story. You add the catalyst right before spraying. The cross-linking takes place very quickly. The terminology is post-cat finishes are very "HOT". The pot life can be as short as 15 minutes to 90 minutes. After that the product starts to gel and harden. The re-coat time on post-cat product is very short. If you miss the window, you have to wait until a full cure is obtained, sand and then re-coat.

Back in the 1970's I repainted a car. Back then base coat, clear coat was a new cutting edge process. I painted the car with a lacquer base coat (lime green), and then I use a post-cat urethane clear coat over the top of the lacquer. The pot life was about 90 minutes and after that, the left over clear coat product turned into a rubbery substance that could not be dissolved.

If you are concerned that a pre-cat lacquer is like IE: "2 part epoxy" or cured polyester resin after you added the methyl ethyl keytone peroxide, (which basically nothing on earth will dissolve after it sets up), I can assure you that pre-cat lacquer is nothing like that.

Unfortunately I can not give you a definitive answer on whether or not very old pre-cat will be repaired as easily as conventional NC or Acrylic lacquers.

But for me at least, the quality of the finish and ease of use is most important. I will let somebody else worry about how to fix the pre-cat finish on my antique TV sets after I am dead and the sets go to a new caretaker.

[walterbeers]

I agree I'm not a pro furniture finisher, and I'm sure there are a lot better ways, stains and finishes to use. I think it looks fairly reasonable, not perfect, but acceptable, and it looks a lot better than it did. Maybe someone, will get the set in the future, can do a more professional job, (assuming the set will still be around). For now, I plan to keep the set, and I'm satisfied.

[walterbeers]

Well, I have it done, at least for now. I'm sure maybe with more time I can improve upon it some more, but it does have good color, and is completely back together and working. Not bad for a color set produced at the end of 1954. I thought I would post some final pictures of this RCA CTC2B, 21CT55. Also in case someone is wondering about the set next to it in the one picture, it's my CTC9. They are 2 of my most prized possessions. Yes, lots of work has gone into it, but didn't really cost me a lot of money. Just the usual stuff, capacitors, some tubes, the color crystal, a doorknob capacitor, a few resistors, etc.

[jr_tech]

A thing of beauty and a joy forever! - (Keats)

One of my favorite early color tvs... still has that great early tv upright packaging, has a tube that can be replaced, has I & Q demodulator system and enough tubes inside to heat a small room!

Good job!
jr