RCA CTC4: the barberized Seville. Update: it is ALIVE, with video and sound!!
 

Last weekend I visited Nick to get that Zenith poster, and exchange a couple more items, and he mentioned that he had a CTC4 he wanted to sell.

To make a long story short I ended up buying it.
This I believe is the Seville model minus the legs. http://i1095.photobucket.com/albums/...h/DSCN1387.jpg

Whom ever owned it before Nick did not take good care of it.
All the tubes (aside from the CRT), the speaker, the back, the legs, the channel selector knob, and possibly other stuff are all missing.

The 21AXP22 has the PNGOD (Purple Neck Glow Of Death) so it seems that I'm going to have to use a 21FJP until I come upon sufficient luck and or resources to bring a good 21AXP22 into my possession.
http://i1095.photobucket.com/albums/...h/DSCN1401.jpg
http://i1095.photobucket.com/albums/...h/DSCN1398.jpg

A nice 21FJP22 with the strongest emission of any of my roundys came with the set so I have a strong jug to put in for the time being.http://i1095.photobucket.com/albums/...h/DSCN1402.jpg

One of the IF cans got knocked off the board, but miraculously the board appears to be just fine.

I'm going to go down in a few minutes and start examining the set in day light (read pulling the chassis and examining it).

Here is a link to some pictures of it...
http://s1095.photobucket.com/albums/...lond%20finish/

I've clearly got my work cut out for me, but still I can't suppress that "Woo Hoo! I finally have got a CTC4!:banana::banana::banana::yippy:" feeling.:D

Nice set!!!!!!! :thmbsp:

Thanks!
This was RCA's second large screen color chassis, and their first "simplified" color chassis.
And considering that modern color TV started here in 1954, this 1955 model is super rare (not taking the less common blond wood cabinet finish into account).

Too bad about the CRT. :no: Will be nice when done!

isnt there some way to pull a vacuum on a crt that took air instead of tossing it? there must be a way, theres ways around everything about these vintage tvs. maybe a pinpoint torch and a way to attach a line to evacuate. i dont know just thowing it out there as i would attempt it with a rare crt b&w or color because when there gone they are gone for good, no loss if it dont work a plus if it did.

Rebuilding is the only way to fix it.

Too bad about the tube, I was hoping maybe something had gone wrong with my tester. Time to begin recapping, then stick that glass tube in it!

Have any of the heaters burned out yet from the poor vacuum, or do all 3 still light up?
How do the neck getters look?
jr

Timmy, from my memory I believe that folks have pulled vacuums on these leakers and had them return to being too gassy to use within months. I have NO intentions of throwing this tube out. There is a group (I know Bob Galanter is a part of it) trying to come up with a way to seal the leaks on 15GP22 and 21AXP22 CRTs so that they can be rebuilt by a professional rebuilder in France, and last a long enough time to financially merit the cost of the rebuild process. I would probably not be able to afford to have it rebuilt for several years anyway, even if the process is perfected tomorrow.

I'm not crazy enough, and don't have the equipment to try redneck engineering that tube back to life in the way you purpose. I would like to ask someone who is more knowledgeable than me, how a tube can still have enough vacuum for the heaters not to burn open, but yet have enough gas inside to fail to work....Shouldn't the getther be able to deal with the gas?

I pulled the chassis about an hour ago and brought it upstairs for examination and some work. here are the chassis shots...
http://i1095.photobucket.com/albums/...h/DSCN1417.jpg
http://i1095.photobucket.com/albums/...h/DSCN1420.jpg

The fly looks good with only a pinch of wax dripped.
http://i1095.photobucket.com/albums/...h/DSCN1418.jpg
http://i1095.photobucket.com/albums/...h/DSCN1419.jpg

A fuse was blown and a replacement was slapped in at some point in the past.
http://i1095.photobucket.com/albums/...h/DSCN1423.jpg

And this just looks like a hack job.
http://i1095.photobucket.com/albums/...h/DSCN1421.jpg

The set uses a metal color crystal.
http://i1095.photobucket.com/albums/...h/DSCN1424.jpg

There is minor damage to the IF board where the transformer got busted off.
http://i1095.photobucket.com/albums/...h/DSCN1422.jpg

One of the CRT socket wires is snapped off.
http://i1095.photobucket.com/albums/...h/DSCN1425.jpg

I see there have been more replies while writing this.

Nick, I accidently left some of the controls on my tester up and when I connected it I got lots of purple quickly and the tester made some new sounds.... I quickly dialed everything back and did the test to confirm what the light show told me.

Jr, all the heaters work, but I haven't seen the getthers yet because between about 57 years of grime and the neck hardware they ain't visible right now.

Congratulations on your acquisition of your first CTC-4, I am personally yet to get me a roundie colour set of any kind as they aren't cheap to ship to Australia haha lol, the day will eventually come when I can budget for one and when I do Videokarma will hear about it! :D Anyhow best of luck with your restoration work, look forward to seeing a photo finish working CTC-4!!! :D

I didn't realize that CTC-4 had a PC board.
Must be the world's first Printed Circuit in a TV !

Also see premium Allan Bradley pot in HV cage.

4's are fun! :banana: A few shots off my Haviland. :D

Far out - What a set :yes: Seeing that chassis makes working on black and white sets seem rather basic :D Good luck with your restoration of this beast! Cheers.

Wow such nice colorimetry. Is yours using a 21AXP22 ?

Thanks for the encouragement all.

A humorous development is that the main power fuse that had a new one jumpered over it was actually replaced by one less than half the current rating of the original, and that device used to jumper it had a cracked rivet causing an open circuit. The replacement fuse was good so I have to doubt that this set saw any use since the time that the original fuse popped.

Gassy
 

"I would like to ask someone who is more knowledgeable than me, how a tube can still have enough vacuum for the heaters not to burn open, but yet have enough gas inside to fail to work....Shouldn't the getther be able to deal with the gas? "

The kind of leak we see in must gassy crt's is not a catastrophic leak, but one that took perhaps 50 years to get to the point where there are enough air molecules in the tube to interfere with the flow of electrons.

Through our experiments with our Helium leak detector, we have terermined that the leaks almost always are caused by a microscopic defect somewhere on the weld, where the front and rear sections of the envelope have been weleded together. We also discovered that something as simple as oil from you fingers can temproarly seal the incredibly small leak.

If left long enough, (maybe another 50 years) it is possible that eventually enough air will infiltrate the tube to enable the burning out of the filiments.

There is no way that we have yet discovered to repair a gassy tube, except to rebuild it. And unless you locate the leak and repair it, the likelyhood of the rebuild working is very low.

You have to remember that the higher the vacuum inside the tube is (10 -6 torr is where you need to be for a tube to function) the stronger vacuum is that is trying to suck the air into the tube. As the vacuum inside the tube degrades (say down to 10 -4 torr) the vacuum inside the tube is pulling less strong on the air outside the tube. So eventually you get to a point where the vacuum inside the tube is not pulling hard enough to suck air into the tube through the microscopic leak in the weld and you reach an equibrilium and no more air enters the tube. At that point you are left with a tube that has too much air inside it to function, however there is still a significent vacuum inside the tube. Enough to still make it implode if struck.

In our experiments with the 15GP22 I probably removed the gun assemblies from at least a dozen tubes. Every one still had a huge amount of vacuum inside, but still the vacuum was nowhere good enough for the tube to function.

Getter flashes are only intended to clean up the remaining air molecules left inside the tube after you reach 10 -6 torr. That would be 1 molecule in 1,000,000. 10 -6 torr is 1/1,000,000 of an atmosphere.
A very good standard grade laboratory vacuum pump, like a Welch 1402, is capable of pulling a vacuum of .010 torr. A vacuum good enough to make a crt work needs to be 10,000 times better than a mechanical pump is capable of. To get a vacuum good enough to make a crt work, you need a diffusion pump or a turbo pump and the tube has to be elevated in temperature to around 600F to excite the gas molecules inside the tube to a point were they can be traped and pulled out of the tube by the diffusion or turbo pump over a period of several hours.

So given the kind of vacuum needed to make a crt work, if the leak took 50 years to polute the tube, you can see how incridebly small the actual leak is.

We are talking about a leak in a weld that is likely not much larger in size than an atom of Ozygen or Nitrogen. We use helium as the trace gas in the helium leak detector process, because the helium atom is many times smaller than an atom of Oxygen or Nitrogen (which is what composes the majority of gas in our atmosphere) and because the He atom is so small it can more easily get sucked through the microscopic leak so we can find the location of the actual leak.

Ideally the best course to fix a leaky tube would be, cut the old gun off, locate the leak on the weld using a Helium leak detector, figure a way to fix the leak (that is the big issue), then retest the tube with the He leak detector to make sure you fixed the leak, and lastly to install a new gun assembly and evacuate the tube and seal it off.

FYI we have already tried re-welding, and that only created more leaks than it fixed. We are presently thinking about either nickel plating over the weld, or using frit glass. But the project has come to a screeching hault because the only rebuilders left are located in France.

Actually it is even less than that... a torr is 1 mm of Hg pressure, and atmospheric pressure is 760 mm of Hg, so 10 -6 torr is 1/760,000,000 of an atmosphere.

jr

Yes, a 21AX. It seems to be a very early production tube, as the screen is greenish like a 19VP22 instead of kind of gray like later tubes. Also no "A" suffix in type number. It produces amazing color when set up correctly. Probably would look spectacular in a 21CT55.
Good luck with yours! We all will help any way we can!!:yes:
Kevin

It does look good in a 21CT55, here's my green screen 21AX:

http://videokarma.org/attachment.php...3&d=1307252941


Bob G also has an original production green tinted AX in his CT55, they make a slightly more saturated picture than the later whitish ones. It looks just like a 21" CT-100, which makes sense.

Thanks for the explanation Bob!

I remember that Jr_tech wanted to know how the getthers looked. They look silver and dark gray to me....
http://i1095.photobucket.com/albums/...h/DSCN1433.jpg
http://i1095.photobucket.com/albums/...h/DSCN1434.jpg

I decided to pull the CRT yesterday here are some pictures.
http://i1095.photobucket.com/albums/...h/DSCN1428.jpg
http://i1095.photobucket.com/albums/...h/DSCN1429.jpg
http://i1095.photobucket.com/albums/...h/DSCN1430.jpg
http://i1095.photobucket.com/albums/...h/DSCN1432.jpg
http://i1095.photobucket.com/albums/...h/DSCN1431.jpg


I've also slowly been cleaning 57 years worth of grime off the chassis.
http://i1095.photobucket.com/albums/...h/DSCN1427.jpg

I've been recaping too. Here is the completed IF board.
http://i1095.photobucket.com/albums/...h/DSCN1435.jpg
The two ceramic cased ones I managed to restuff, but the rest had "bakelitized" paper tubes the ends of which my soldering iron could not melt or even soften! I had to double up to get two of the values....I replaced a .027 with a .022 and a .0047 in parallel, and I replaced a .056 with a .047 and a .01 in parallel ( I know this not wonderfully exact, but it is an improvement over the .068 maroon drop that was in there).

I also remounted the IF shield after the recap.
http://i1095.photobucket.com/albums/...h/DSCN1436.jpg

With luck in the next couple of days I'll have the recapping done good enough to do a test power up.

I have dug out of my stocks all the tubes this set needs except for the Damper, H output, HV rect., the 6CL6s, the 6AN8s, and the 6AZ8s (I managed to find a majority of RCA branded used and NOS tubes for this set:banana:). I'm going to sift through my unboxed tubes and see if I have any. If not I'll see if nostalgiaair lists any sub types that I might have.

Damn, this thing's gonna come back to life faster than my Director 21 did! Show us color bars!!!

You are corrrect. I always get that confused because most of the scale on our militor meter is graduated from 1 torr to .001 torr and the top end of the scale from 1 torr to 1Atmosphere is only 1 graduation, so I always think 1 torr is 1 atmosphere. Sorry for my brain fart :-)

Well since my last post I found replacements for the missing damper, HV rect, and H output tubes, but I have not found the others in my stocks yet....Also it seems that there are no compatible types according to two tube sites I've checked. :headscrat

I finished replacing all the paper caps, and found that this set more closely matches the riders schematic than the Sam's folder from the ETF.
The only cardboard tubes left under chassis are either lytics or restuffed papers.
http://i1095.photobucket.com/albums/...h/DSCN1437.jpg

I realized that one of the doubled up caps on the IF board I had a single-cap replacement for and decided to swap my first replacement for it as I needed the .0047 that was part of the first replacement elsewhere.
http://i1095.photobucket.com/albums/...h/DSCN1440.jpg

After doing all that it was very late and I decided to call it a night thinking I had reached my goal of ousting all the paper caps, then as my head hit the pillow I thought "Oh sh!t I forgot three! Oh well tomorrow then.", and this morning I swapped them out. Now I can say all the papers are gone.
http://i1095.photobucket.com/albums/...h/DSCN1439.jpg

Now to try to find the remaining tubes and hopefully get enough new lytics in for a test power up.

Yesterday was basically me barely managing to scratch up enough caps to replace the papers, and now it will be the remaining tubes and the lytics. Wish me luck!

so what you are saying is that for a crt like the 21fb,21ax needs10-6 torr of vacuum so what would the hg be for that amount? i ask because i have a gauge that i think has hg on it and is used for vacuum. i only thought vacuum was measured in inches, like in autos.

One atmosphere of pressure pushes on us with about 14.7 pounds/square inch. That pressure will support a column of Hg about 29.9 inches high in a Hg barometer... that is about 760 mm of Hg. One mm of Hg is defined as 0ne Torr.

So to go from inches(of Hg) to Torr, just multiply by 25.4 (mm/inch conversion).

jr

so this is physics, wow, so then 10-6 would be what torr because there is 2 numbers. one mm hg defines one torr but what number to use, 10-6, why a dash and not a point.

It's 10 to the minus 6, scientific notation...

ok thanks... i was never good with math,lol....

or in simple terms 10 to -6 torr is .000001 of 1/760th of an atmosphere

(one atmosphere being 14.7PSI) so 14.7PSI * .000001 / 760 = 1.934 * 10 to -8

in PSI it would be 0.00000001934 PSI or as a fraction

1.934
------------- PSI
100,000,000

Someone please check my math to make sure I have all the decimal points correct. I came up with 1.9342105e-8 PSI

Neon Bulb Time
 

Neon Bulb Time is from 1 Torr to 1 millitorr.
We can't have any spacecraft power on or else the chance of "corona" arc is high !

I see the CRT was rebuilt near the end of 1965.

Congratulations on the CTC4!

I have a question for CTC4 owners. I noticed that RCA in I believe this chassis only, tried to get away with taking the intercarrier audio directly from the video detector instead of having a separate intercarrier detector. The separate detector for intercarrier sound would facilitate better sound rejection to minimize the 920kHz beat.

I believe this was unique only to the CTC4. Do any of you with working CTC4's see the difference with later sets or actually see any detrimental effect of the possibly greater 920kHz interference?

Another thing: was the title of this thread intended as a playful reference to the Rossini opera? I wanted you to know I appreciated the humor, intended or not.

Progress & Questions
 

Okay! I'll start with the questions....

Is it necessary to replace the seleniums before a power up?

And to those whom have installed 1N4007s in place of the seleniums what if any added series resistance value did you use?

And to those who have used newer CRT types than the 21AXP (Nick...) how did you connect the HV button on the CRT to the HV connector on the HV cage? I've got my fingers crossed that this can be safely done without cutting the HV plug off the plastic CRT cover as I entertain the hope of someday having a good 21AXP22 to install......

Also which tubes are supposed to have shields on them?

As for progress......

I've disconnected the Doubler and B+ from the transformer and done a power up to confirm that the power xfmr is still good. The fillaments lit so it would seem that my power transformer is still good.:thmbsp::yes:

I'm presently variacing the set with only the doubler caps and seleniums connected to the B+ winding on the xfmr (I unsoldered the B+ lines) so I can reform 3 of the lytics and check the seleniums under power simultaneously.

I've been continuing to clean the chassis as well.
I thoroughly cleaned the inside HV cage including removing the HV rectifier cup for a cleaning.
The place where the HV rectifier cap connects to the fly was missing most of it's wax and kinda loose so I took some dripped wax and built up the wax around it for added support. I was concerned that the the connection on that lead was open so I checked the resistance between it and the HOT cap lead and got within 10% of what sam's lists that resistance value to be which is a good sign.:) I also for the briefest of moments touched the barrel of my soldering iron to the wax on the HV winding of the fly to melt the outer layer of wax in order to fill in some small cracks in the wax coating.
I replaced the HV cage lytics as well. I replaced the 20uF 25V caps with 22uF 250V replacements, and the 5uF 25V with two 2.2uF 63V Radio Shack "how the heck can new caps have some ESR???" specials connected in parallel (I'll likely change these turkeys later for a better part).

Here are some pictures.....More can be found in the link from the first post in this thread....
http://i1095.photobucket.com/albums/...h/DSCN1481.jpg
http://i1095.photobucket.com/albums/...h/DSCN1480.jpg
http://i1095.photobucket.com/albums/...h/DSCN1479.jpg
http://i1095.photobucket.com/albums/...h/DSCN1467.jpg
http://i1095.photobucket.com/albums/...h/DSCN1475.jpg
http://i1095.photobucket.com/albums/...h/DSCN1474.jpg
http://i1095.photobucket.com/albums/...h/DSCN1482.jpg
http://i1095.photobucket.com/albums/...h/DSCN1486.jpg
http://i1095.photobucket.com/albums/...h/DSCN1487.jpg
http://i1095.photobucket.com/albums/...h/DSCN1489.jpg
http://i1095.photobucket.com/albums/...h/DSCN1490.jpg

EDIT: yes the title is a me using a word play on the title of the opera "The Barber of Seville" as a pun....Glad one a' ya uncultured swine (I'm joking here) gets it. And NO I'm not a fan of Opera (classical aint bad, and I like most popular music from the 50's to the 80's, but Big Band/Swing is what I really LOVE).

My CTC-4 came with modern silicon rectifiers already in it, I just run it a little low on input voltage and read B+ till it's correct. I toyed with resistors before, but they dissipate a ton of heat.

The HV tower uses the exact same connection as a Tektronix o-scope, that's where I stole my lead from. I had to desolder the original wire, then soldered on a HV cup with a longer wire that matches the connection on the CRT (the type with a silicone cup). I think I might have given the one I made to Bob or Mark, you can make your own the same way if you get your hands on one of those leads.

Here's an Ebay link, but $70 seems pretty steep for just the wire: http://www.ebay.com/itm/Tektronix-pn...item43ac0df518

Perhaps you can cannibalize a broken scope?


Just the ones that have grounding fingers attached to the chassis.

I used to have a busted Tektronix scope....sh!t now I wish I had not chucked it into a radio club swap meet donation auction!

So basically all tubes except the the 6AQ5s, octals, and what is inside the HV cage need to have shields. Right?

You got it!

Went to Chester's yesterday and got the remaining tubes and some lytics I needed.
Yesterday night I brought it up on my variac with the plate lead of the HOT and the damper tube unpluged, and was able to tune in good sound from my signal source, and confirm that the H osc. is working properly.

I didn't try for a raster as the screen voltage on the HOT was too low for me to justify connecting the HOT and damper. Also the vertical osc. appears to be dead.
I haven't had enough time to do much today so far, but do know that an open 11K resistor is to blame for the low screen voltage. I may not have an exact replacement for that resistor, and will likely have to do some scrounging later on.

I bought some HV lead at Chester's and striped, folded, and soldered a long section of wire at the end so that it has a decent mesh with the HV connector. Not the best, but it should be good for a test later on.

I'm very happy that the RF and IF seem to be working! :banana:
With luck I may soon have a raster.

We have got a RASTER!! :banana: :yippy::beerchug::banana:

http://i1095.photobucket.com/albums/...h/DSCN1491.jpg

About an hour ago I finished preparations and proceeded to do a full power up including the FULL horizontal stage. The best replacement for the bad 11K ohm 10W screen resistor for the HOT I could find was a 10K 7W, but I figured that it would last long enough for a full test, and I was right.
After putting the sub in with the top lead of the HOT still disconnected I read 110V. Sam's calls for 160V at the screen. I also decided not to sweat over not having the vertical osc. running the other day as I noticed that the plate of that tube gets it's voltage from the boost line, and thus would not work unless I went ahead and connected the flyback up to the HOT and damper.

The HV was only 15 KV (and falling) on the second test (I was too excited on the first brief power up to read the meeter). I figure that with low HOT screen grid voltage and all new tubes across the board that this is not too bad for a first power up.

I did not have sound during the test which I attribute to me messing with the tuner setting earlier in the day. This set may possibly have video for all I know.

This was the last task of the night. I'll see if I can do more tomorrow.

Congrats! It;s always a good feeling when the raster appears for the first time.

We have now got VIDEO and sound!:banana::banana::yippy::banana::banana:
http://i1095.photobucket.com/albums/...h/DSCN1522.jpg
http://i1095.photobucket.com/albums/...h/DSCN1520.jpg
http://i1095.photobucket.com/albums/...h/DSCN1519.jpg
http://i1095.photobucket.com/albums/...h/DSCN1508.jpg
http://i1095.photobucket.com/albums/...h/DSCN1506.jpg
http://i1095.photobucket.com/albums/...h/DSCN1500.jpg

Well I got my signal issue sorted and did another power up. This time at the suggestion of a member of ARF to my thread there; I meetered the screen of the horizontal with the plate lead of the HOT connected, and I got 150V. This is close enough to the 160V sam's calls for that I will not loose sleep over the resistor that is in there(at least for now). When I first powered it up with signal the video was so weak I almost missed it. I did see it though and synched up the horizontal and vertical. Even with the contrast maxed the video was really weak, and the deflection would not keep synch so my mind went straight to AGC. The control was near max already and maxing it did not yield enough improvement so I started jiggling tubes in their sockets and it was the second IF tube that fixed it. In fact after shifting that tube to a better position the signal was overloading the set. A quick readjust of the AGC and all was well (except for the dead color circuits and a some other bugs).

The HV stayed at about 20KV this time and adjusting the regulator would only reduce it. After about an hour of operation the fly was pretty warm.
I think it is about time for me to read and preform the Sam's horizontal adjustment procedure on this set....

The screen controls were sticky and the red is stuck. Between this and the dirty tube sockets I believe that it is time to get some DeOxit and start cleaning controls and contacts.

WOO HOO! Just a bit more and it will be working like new again!

Good job, Tom!!!

I knew it was a good chassis the minute I laid eyes on it, all it needed was the attention of a good tech to bring it out of hibernation. Image still looks like hell, but you can tell everything's trying to work. Worry about the color section last, for now you need to turn your attention to all the pots on the convergence panel. I promise every last one will end up having something wrong with it, and you'll never get it adjusted right without them being good. So fix all the bad pots, then move on to other sections.