View Full Version : RCA CTC4: the barberized Seville


Electronic M
12-19-2011, 12:40 PM
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 for slightly more than 400$.
This I believe is the Seville model minus the legs. http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1401.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%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

Komet
12-19-2011, 01:06 PM
Nice set!!!!!!! :thmbsp:

Electronic M
12-19-2011, 01:24 PM
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).

mstaton
12-19-2011, 01:27 PM
Too bad about the CRT. :no: Will be nice when done!

timmy
12-19-2011, 05:00 PM
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.

miniman82
12-19-2011, 06:48 PM
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!

jr_tech
12-19-2011, 06:58 PM
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

Electronic M
12-19-2011, 07:36 PM
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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1417.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1420.jpg

The fly looks good with only a pinch of wax dripped.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1418.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1419.jpg

A fuse was blown and a replacement was slapped in at some point in the past.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1423.jpg

And this just looks like a hack job.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1421.jpg

The set uses a metal color crystal.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1424.jpg

There is minor damage to the IF board where the transformer got busted off.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1422.jpg

One of the CRT socket wires is snapped off.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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.

Aussie Bloke
12-19-2011, 08:33 PM
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

NewVista
12-19-2011, 08:54 PM
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.

stromberg6
12-19-2011, 09:57 PM
4's are fun! :banana: A few shots off my Haviland. :D

Glenz75
12-19-2011, 10:20 PM
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.

Electronic M
12-19-2011, 11:07 PM
4's are fun! :banana: A few shots off my Haviland. :D

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.

ohohyodafarted
12-20-2011, 03:53 PM
"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.

jr_tech
12-20-2011, 04:50 PM
10 -6 torr is 1/1,000,000 of an atmosphere.


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

stromberg6
12-20-2011, 04:57 PM
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.

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

miniman82
12-20-2011, 06:18 PM
It does look good in a 21CT55, here's my green screen 21AX:

http://videokarma.org/attachment.php?attachmentid=170633&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.

Electronic M
12-21-2011, 02:20 PM
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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1433.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1434.jpg

I decided to pull the CRT yesterday here are some pictures.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1428.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1429.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1430.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1432.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1431.jpg


I've also slowly been cleaning 57 years worth of grime off the chassis.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1427.jpg

I've been recaping too. Here is the completed IF board.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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.

miniman82
12-21-2011, 05:57 PM
Damn, this thing's gonna come back to life faster than my Director 21 did! Show us color bars!!!

ohohyodafarted
12-22-2011, 04:52 PM
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

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 :-)

Electronic M
12-23-2011, 02:18 PM
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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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!

timmy
12-23-2011, 03:56 PM
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.

jr_tech
12-23-2011, 04:25 PM
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

timmy
12-23-2011, 05:05 PM
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.

miniman82
12-23-2011, 05:53 PM
It's 10 to the minus 6, scientific notation...

timmy
12-23-2011, 06:20 PM
ok thanks... i was never good with math,lol....

ohohyodafarted
12-23-2011, 06:39 PM
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

WA3WLJ
12-23-2011, 08:27 PM
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 !

ChrisW6ATV
12-24-2011, 12:15 AM
I see the CRT was rebuilt near the end of 1965.

Penthode
12-24-2011, 03:21 AM
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?

Penthode
12-29-2011, 12:29 AM
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.

Electronic M
12-29-2011, 01:29 AM
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/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1481.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1480.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1479.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1467.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1475.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1474.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1482.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1486.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1487.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1489.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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).

miniman82
12-29-2011, 10:46 AM
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?


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.

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?

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-154-0672-00-7603-7403N-Small-Graticule-CRT-Used-Working-/290649404696?pt=BI_Oscilloscopes&hash=item43ac0df518

Perhaps you can cannibalize a broken scope?

Also which tubes are supposed to have shields on them?


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

Electronic M
12-29-2011, 12:44 PM
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?

miniman82
12-29-2011, 12:59 PM
You got it!

Electronic M
01-01-2012, 06:27 PM
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.

Electronic M
01-02-2012, 02:03 AM
We have got a RASTER!! :banana: :yippy::beerchug::banana:

http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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.

mstaton
01-02-2012, 02:07 AM
Congrats! It;s always a good feeling when the raster appears for the first time.

Electronic M
01-02-2012, 03:27 PM
We have now got VIDEO and sound!:banana::banana::yippy::banana::banana:
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1522.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1520.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1519.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1508.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1506.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/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!

miniman82
01-02-2012, 03:39 PM
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.

IsthmusTV
01-03-2012, 08:52 AM
Wow, Tom congratulations! I'm amazed at how fast you got it up and running-- truly inspirational.

-Clark

Electronic M
01-03-2012, 01:58 PM
Thanks!
The main reason I could do this so fast is that I had most of the right values of paper caps on hand, and enough extra wrong values to make accurate enough (I fudged some values in the audio stages because those stages are not critical, and I rarely use the sound on my sets) replacements for values I was missing. I also was on Christmas break, and until today I was able to dedicate the better part of a few days on end to working on it.

My plan of attack will be to get De Oxit tonight to clean contacts, and this week end swap the CTC4 cabinet in the garage for a roundy in my bed room/work shop/display area/big mess. Then once I have the CRT mounted in the cabinet I will concearn my self with the deflection tweaks, and then color issues.

I'll have some questions soon. Gota run!

Glenz75
01-03-2012, 05:40 PM
You've made excellent progress with this one, must have given you goosebumps when finally a picture appeared on the screen :yes: Great stuff, you'll have nice set when its all done! Cheers.

Electronic M
01-03-2012, 07:35 PM
Thanks!
I was barely able to get any video at first and almost did not notice that I even had any. Once I got it to synch I was briefly very excited, but it was so weak that it was difficult to tell what I was at on low contrast images. This and the unstable synch (the signal was so weak that I could barely even get a picture of the synch bar when the vertical rolled) quickly made my inner technician take over and start trying to improve the signal using any tricks at my disposal. Once I succeeded at getting the video back to a reasonable level I went right back to excitedly celebrating this significant mile stone, and proceeded to watch, for an hour, a level of picture quality that I would not bother to watch on any other set I own. I will admit that I enjoyed watching it more than any of my other, presently much better preforming, restorations. :)

Now that I have time to type more I have three questions for those whom have used these sets with the newer roundy tubes.

First is it a good idea to keep using the field neutralizing magnets on the front of the CRT with a 21FJP?

Second those knurled metal things on the outside ends of the convergence yoke that point towards the back of the set, are they the static convergence adjusters?

Third is how do I preform safety glass removal on a CTC4?

This set is nearly a decade older than any color set that I've worked on before so it is a real learning experience of how they designed them in the early days, and a good chance to sharpen my trouble shooting skills and put those skills to the test.

miniman82
01-04-2012, 12:59 AM
is it a good idea to keep using the field neutralizing magnets on the front of the CRT with a 21FJP?


I tried to use them with a glass tube, but they are too weak to fix impurities in the center of the screen. I also gave you that plastic ring with the hairpin magnets on it right? CTC-9 chassis use the same thing, I'd strap that to the back of the tube and see if you can get good purity between that and the edge purity magnets from the CTC-4. The hairpins come in pairs and I think one is missing. You'll want to remove that one...

Second those knurled metal things on the outside ends of the convergence yoke that point towards the back of the set, are they the static convergence adjusters?


More like beam positioning, but call it what you will. Basically you center all the dynamic convergence controls, then use the knurled knobs on the conv yoke to set up a roughly converged center cross pattern. From there, you follow the Sams dynamic proceedure RELIGIOUSLY till it starts to look better. Then you do it 5 more times till it looks right. :D

Oh, don't forget to do red purity before any of that other stuff. Purity first, then convergence. ETF has the CTC-4 Sams posted if you don't already have one.

This set is nearly a decade older than any color set that I've worked on before so it is a real learning experience of how they designed them in the early days, and a good chance to sharpen my trouble shooting skills and put those skills to the test.

Actually, the 4 was one of the easier sets I've worked on. Most things remained about the same after the CTC-4 and 5, which were each special in their own ways. The 4 detected color on different axes than any other set before or after: R-Y and G-Y vice the typical R-Y and B-Y that came later, or I/Q that came before, along with having high level demod. The 5 had a funky demodulator circuit using 12AT7's. The CTC-7 and everything thereafter looks the same on paper, subtle changes only. Most of it is different tube types, but later ones also shed an IF stage or 2 due to getting tubes with higher gain.

wa2ise
01-04-2012, 08:42 AM
EDIT: yes the title is a me using a word play on the title of the opera "The Barber of Seville" as a pun...

That was an excellent Buggs Bunny cartoon! :)

dieseljeep
01-05-2012, 08:38 AM
Actually, the 4 was one of the easier sets I've worked on. Most things remained about the same after the CTC-4 and 5, which were each special in their own ways. The 4 detected color on different axes than any other set before or after: R-Y and G-Y vice the typical R-Y and B-Y that came later, or I/Q that came before, along with having high level demod. The 5 had a funky demodulator circuit using 12AT7's. The CTC-7 and everything thereafter looks the same on paper, subtle changes only. Most of it is different tube types, but later ones also shed an IF stage or 2 due to getting tubes with higher gain.[/QUOTE]
Nick.... The CTC5 had two different chassis that year. The better model had a color circuit that was simular to the later chassis.

mstaton
01-05-2012, 01:18 PM
The "super"=cheaper, the "deluxe"=better. I have a "super"

miniman82
01-05-2012, 07:59 PM
The CTC5 had two different chassis that year. The better model had a color circuit that was simular to the later chassis.

Yes, you're referring to the differences in the 'Super' and 'Deluxe' chassis. I do admit to liking the circuit with 12AT7's though, pretty nifty. :thmbsp:

Electronic M
01-08-2012, 04:07 PM
That was an excellent Buggs Bunny cartoon! :)

Agreed!

Nick, what does "high level demodulator" mean?

As of Wednesday I got the cabinet up stairs and dismantled the CRT mask/safety glass/trim assembly for cleaning.
On Thursday I cleaned the disintegrated rubber gasket from the Glass and mask. I used Goof Off to get the rubber off the glass, and started to use it on the mask. I then realized that it would be too harsh on the paint of the mask, and switched to rubbing alcohol, which is also not particularly good for the paint, but less harsh and yet still efficient at dissolving the rubber goo.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1534.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1536.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1543.jpg

On Friday I started to polish the the the brass trim. It was not going fast at all on the lightly tarnished piece I started on. After that piece was good on Saturday, I grabbed the worst corroded piece I had and started experimenting with technique, and found that vigorously scrubbing the polish on with a tooth brush was VERY effective. Sadly even though it looks good from a distance it is clear up close that these pieces are brass plated copper, and that all pieces have spots of varying size where the plating was corroded through over the years.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1540.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1546.jpg
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1547.jpghttp://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1549.jpg


Nick I found out why those corner pieces were loose....Their retainer clips are busted. On the left is a good one the two others are the bad ones.http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1552.jpg

I mounted the corner pieces with the bad retainers at the top, and reinstalled everything in this picture.http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1561.jpg

I did a quick green purity (at the time the red would not work) and neglected to take a picture. I was confounded by the red not working for some time, but then found that there was a lead touching the screen wire terminal that was shorting the screen to ground:yikes: It looked much better after that.

The color circuits work, and I did some minor convergence tweaks to improve the picture. I still need to spray deoxit into some of the convergence pots as they can get squirly and mess with the deflection circuits. Still tons of adjustments to do which I'm going to need to fabricate a yoke extension cable to preform, and then hope that either the convergence will reach where I need it or that the set will not mind having the convergence yoke unplugged.

http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1556.jpg
And what Nick has been wanting to see.....Color bars.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1558.jpg
My camera made the left side look worse than it is, but it is clear that the demods need adjusting.

There is a nasty imtermitant that kills the signal at the second IF tube. I'm begining to wonder if the socket is bad.....

I actually lifted that set (minus the top lid) on to the black roundy my self. If it was not for the sore mussels I'd have been pretty proud of doing that.:nono::D

old_tv_nut
01-08-2012, 07:10 PM
Hi level demods go directly to CRT grids with no further amplifiers.

miniman82
01-08-2012, 08:21 PM
Correct. If you look at most other schematics, you'll notice that each color has an output tube. On the 4, the demods go directly to the CRT without passing go or collecting $200. Thus it's high level, where the circuits requiring amplification are considered low level.

ohohyodafarted
01-09-2012, 06:07 PM
Tom,

The trim is SOLID brass. It is not plated copper. Brass is acutally COPPER, that is alloyed with zinc. The copper pits or spots you see in the brass finish are areas where the zinc has likely been depleatd from years of chemical corrosion. When that happens the base metal COPPER is what is left and it looks like it was brass plated copper. I can asure you that the trim is solid brass and you can steel wool and scotch brite until you are blue in the face and you will never wear through the plating because it is not plated, it is solid brass. For an easy way to polish solid brass trim follow this link to my web site.

http://antiquetvguy.com/Web%20Pages/My%20Methods/BrassRefinishing/BrassRefinishing.html

Good Luck,
Bob

Electronic M
01-09-2012, 07:46 PM
That is pretty cool Bob! I'll have to try that sometime.


I'm trying to preform the horizontal adjustments and have hit two walls the worst of which is that the linearity coil slug is BADLY frozen (I sprayed some deoxit gold in there and nothing) I'm afraid to proceed because I may end up breaking it. Please help!

Secondly in the HV adjustment procedure it says to adjust the HV control for 25KV, and the most I can get before bottoming out the control is 20KV. Is this something that will shake out if I iterate the procedure a few times?

Putting a meter in place of the HV fuse I'm getting around (ie a little over) 175mA of current.

miniman82
01-09-2012, 08:18 PM
Sounds like the output tube isn't being driven hard enough, have you checked the oscillator for correct performance? My CTC-4 will make 25kv no problem, same with the 21-CT-55. They have very stout HV supplies, so if you can't get more than 20 I'd look for issues in the drive or make sure it's not being dragged down somehow. Check that the output has the correct negative grid bias, and make sure the waveform going into it is of the correct amplitude and shape. If that's not it, juggle HV rectifiers till it comes up. I went through 3 of them before mine was stiff enough, just because they are new doesn't mean a whole lot. I've found that color sets in particular are very picky about what rectifier they have in them.

Electronic M
01-09-2012, 08:49 PM
Before the first power up I adjusted for the EXACT HOT grid drive voltage called for in sams as a safety precaution. The wave form looked decent, but I did not compare it to the sams at that time.

I just preformed the synchro-guide horizontal adjustment for equal peaks so the drive may have fluctuated, but I seem to recall that the HV was hovering at around 20KV before that so it may not have affected the drive level.

The sam's High Voltage Adjustment procedure is to,with contrast and brightness down, adjust the HV pot for 25KV connect a 0-500mA meeter (I only have a 0-250 unit on hand) across the HV fuse terminals, and adjust the linearity slug for minimum current. Then reset the cont. and bright controls for a raster, and adjust the drive pot until drive bars appear then back off until they are gone.

I was planning to iterate the process until things improved, but I'm hung up at the linearity adjustment because the lin. coil is stuck almost like gremlins have been dumping excess super glue that they have been using elsewhere into the lin coil.

Anyone know how to unstick linearity coil slugs? Even if I skip linearity and go to drive the linearity adjustment will be done in the next step or two and hang me up again then.

miniman82
01-09-2012, 11:47 PM
Try a new rectifier before you do anything else, then you can hit the lin coil with a hairdryer set to maximum warp to unfreeze it.

Electronic M
01-10-2012, 12:26 AM
Well this sucks!! The damn flat head screw head on the copper adjuster rod for the linearity coil snapped off, but I finally got it loose using a combination of Goof Off poured in the track for the ferrite core and heating the coil by connecting it to 2 flashlight cells thus heating it.

I think I need a new core/copper adjuster rod assembly. Here is what it looks like..
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1563.jpg

I'll try to see tomorrow if my RCA 9-T-246 has a similar core in one of it's coils that I can scrounge as a replacement for the original core with the destroyed adjuster threading.

Been a lousy day between the rotten stomach bug that ruined my sleep Sunday night as well as making my folks tell me to skip school on Monday, and damaging this part. Ugh.

Edit: all this happened before your post Nick.

miniman82
01-10-2012, 11:41 AM
Same thing happened to my CT55, I just turn it with needle nose pliers. It should be possible to file a new slot into it, just be careful. Also, I always wanted to try brazing a knurled knob onto one of those.

Electronic M
01-10-2012, 08:58 PM
Thanks for the advise Nick!

My file is a tad large, but if I can get the slug to rotate freely enough I ought to be able to get a screw driver to work with it after filing. I can't comment on the 21-CT-55 layout, but it would be kinda awkward to adjust the linearity control on the CTC-4 with pliers considering they wedged it between the damper and the HV cage. Not what I'd call a particularly good good place for it, but at least it is not as buried as the same adjustment in the CTC-16 (I tend to wear rubber gloves when doing live chassis horizontal adjustments on my 16's as the controls tend to be cramped, and uncomfortably close to dangerous voltages and searingly hot output tubes :thumbsdn:).

I'll try some other HV rect. tubes, but doubt they will fare better than what is in there. The tube in there is perhaps the first 3v filament HV rectifier that I've seen that will peg the needle on my tube tester, although I've heard the mantra that the best tester of TV sweep tubes is a TV set.

miniman82
01-10-2012, 09:14 PM
What the tester says means squat when it comes to HV rectifiers, unless an open or short is indicated. They simply don't test at a high enough voltage to get reliable results.

mstaton
01-10-2012, 11:15 PM
That is so true. I struggled with my 9 with strange HV issues. I could hardly adjust the HV up or down. the regulator and rectifier tested good. I replaced both with NOS and now works great. Tube testers cant always find problems with HV tubes like miniman said.

Electronic M
03-01-2012, 02:27 AM
Been back on it for a bit, and here is what has been happening.

After my last post I scrounged a replacement slug from the width coil of my 9-T-246 that seems to be the best thing I have on hand. pictures below.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1571.jpg

http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1575.jpg
The HV was (and is still) at 20 KV. The dead IF intermitant that was bugging me devolved into a completely dead IF.
I then got too busy to touch the thing for several weeks.

I got back to it over the week end.

The IF has gone back to intermitantly not working from being dead merely by sitting around. I'm fairly sure this set will need an alignment at some point to work right as color sound and monochrome don't seem to lineup as well as they should.

I did not feel like messing with the IF and HV issues, and instead began tweaking the color circuits. It was hard at first because I did not have a nonmetalic alignment screw driver that was long and slender enough for the dual-core transformer let alone two to tweak both slugs at once. So I went to Radio Shack to see if they had those tools available, and let me tell you that I felt like I was in a grocery store that doesn't stock bread when I was told that those tools haven't been on the shelves for a long time! I ended up making my own alignment tools from some used up mechanical pencils I had laying around from the previous quarter of college which were waiting to be thrown out (good thing I didn't get to that). Shown below are my home made alignment tools.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1618.jpg

http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1619.jpg

I have the color adjustments a good deal better than before, but there is still much room for improvement.
http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1621.jpg

http://i1095.photobucket.com/albums/i469/ElectronicMemory/RCA%20CTC4%20Seville%20%20blond%20finish/DSCN1624.jpg

Think I'll go at it some more tomorrow......I should really get to bed now.

zenithfan1
07-01-2012, 12:56 AM
Hey Tom, this thing is really coming along. It looks good, I saw it in person before you got it. How's it going now? Have you had the time to keep working on it? Good job!:thmbsp:

Electronic M
07-01-2012, 01:54 AM
A heck of a lot has transpired since my last post in this thread: College finals, a move from an apartment into a sizable house, work on the CTC-4, and I have on going remodeling(my folks are counting on my skills), emptying out of my families HUGE storage unit and work to get my stuff set up and arranged(which is tough to do considering that the other two things eat up a comparable amount of time to college).

I have not mannaged to work on the CTC-4 since the move, but before that I was working to remove the rust from the tuner shields and making decent progress(I lost some screws though :sigh: ). It was coming along nicely and almost done, but it is starting to rerust so I may just spray paint the offending surfaces silver and say 'good enough'. Part of me wants to use lacquer, but I don't have a great budget and want to save where I can.

About all the actual 'work' I've done on any of my equipment was setting up my stereo/video system (which not only is unfinished, but already needs to be mostly redone because of new finds changing the way I want to do things), fixing an Atwater Kent model 40 for (and with) a friend, and starting to spray paint a rusty TV cart that is a factory accessory for a Zenith set I like.

As the set sits the alignment is lousy, that damn IF intermittent persists, and I feel like, given the behavior of the color demods tinting the raster(or was it selective weak colors...crap I'm starting to forget things!), that there are probably off tolerance resistors that I need to look for and replace before taking Nick up on his generous offer to align it for me. Once it is aligned that may be it for the electronic end of the restoration unless I buy some fresh pots for the convergence board. I really doubt that I can preform the kind of cabinet restoration this set needs(I want to teach myself refinishing etc. later this summer if I can but don't know if I will have time), but I don't know if I will be able afford some of the repro parts I need for this set this year let alone pay for someone to restore the cabinet.

I've got a lot of projects calling for my services at present, but one of these days I'll get back on it.

miniman82
07-01-2012, 09:51 AM
Tom,


There is a guy right there in Milwaukee that can handle the cabinet for you, he did my CT-100 for me and it turned out better than new. Didn't charge too much either. Hit up Bob Galanter for his contact details, guy's name is Dennis.

Electronic M
04-23-2020, 04:29 PM
I'm back on the chassis after only a brief ~8 year break.:eek: lotta water under the bridge since then. I got my EE degree and a job. When I got this Seville way back when I had around 10 monochrome TVs, 2 tube rectangular color sets, and 2 CTC15 clones....I now own every RCA color before the CTC-7 (2 each CTC4 and 5), Philcos first production color and Motorolas third (which even combined together are rarer than any RCA). And own or have serviced almost every RCA roundy from CT-100 to CTC-20 except the 7 and 10-12....

This resto originally went on hold due to a move and the sets apparent need for an alignment....in the mean time I have acquired sweep alignment equipment a good 21AXP22 to install, some cabinet restoration skills, a replacement CTC4 Havilland bottom board to replace the bowed one in my Seville and even a complete CTC4 director in better condition than this Seville....when I stopped working on the Seville chassis it had the tuner bracketing and shields disassembled for cleaning and rust removal (it all rerusted since then), a number of kludgy parallel caps and lousy ancient 70s NOS lytics from Chester electronics that were slightly leaky when acquired but better than the originals I also had forgotten to solder some of the AGC caps I changed. :o ...I also had a mishap where I stepped on the selenium rectifier and bent it to heck....
So why am I picking this basket case up? Well I was trying to get the picture to look GOOD on my CTC4 director and was leaning towards doing an alignment on it, but decided to practice on my worse Seville chassis first so if I screw up there's nothing to loose... Also I have all the extension cables stiting out to use the director as a test jig and the Seville chassis has been sitting out for almost a decade so it couldn't be easier to pick it up and start on it. So I replaced the seleniums, the percentage of lousy caps I used last time, changed the junk 2nd IF tube socket, painted the tuner brackets and IF shield an automotive gray that looks better than rust and it lived again and ran as well as it did before if not marginally better.
Before trying an alignment I went through all the resistors in the IF changing any off tolerance and that helped, then I went through the luminance channel and AGC/sync sep resistors and that really helped....color sync and demodulation was still a bit wonky though so I did the resistors there too...now it looks like I may be able to call it done soon. The 2 issues I have left are the fine tuning needing to be at max to have a good picture (I'm going to adjust the channel osc slugs) and I need to check and address the low HV issue I had years ago.
Once I get it working I'm probably going to put it in the director till I can get the director chassis as good or better. The Seville cabinet needs a lot of work and I need either a new HV cable insert for the shroud or to fix the snapped off CRT contact spring on the old one (the one in the director was broken and arcing when I got it and I swapped the Seville one into the director.
I don't want to work on the directors original chassis until I can track down 5 more good 6AZ8s and a 6AG7... The 9 pin sockets especially the IF are delicate and I only have 1 correct good spare left. If someone has those tubes and wants to sell them I'd be grateful...

old_tv_nut
04-23-2020, 04:58 PM
Onward!

JohnCT
04-24-2020, 06:54 AM
I got my EE degree and a job.

Congratulations sir!

John

Electronic M
04-24-2020, 10:43 AM
Congratulations sir!

John

Thanks.


Last night I checked the HV and it is measuring a steady 25KV.

I just need to go after the tuner, stick this in the director cabinet and converge it...the convergence yoke is the only cable I don't have the fittings to make an extension for. My solution was to leave the one in the director cabinet unplugged and grab the yoke from the Seville to act as a dummy load for the chassis. The convergence yoke plug is essentially a 6-pin version of the battery connector on a tube Zenith transoceanic...I have a 5 pin cable and socket off an old Baldwin organ, but no 6-pin connector.

When I do get the Seville cabinet done and ready for 21AXP I'm going to need to do something about the pictured cable. There used to be a contract spring (curved piece of flat spring steel) coming from the center of the bullseye that broke off and has been lost... I'm considering trying to solder a flashlight spring on and see if that works.

Electronic M
04-24-2020, 02:36 PM
From the kludge department:

Electronic M
04-26-2020, 03:46 PM
Friday night I got the VHF tuner dialed in had to adjust the slugs for each channel plus the hidden master slug for CH13 and a coarse osc adjust trimmer. The procedure I followed was to start at 13 making the coarse adjustments to give it enough range and work my way down the channels.
I started. By going the other way and made things worse before making them better.
All but one channel has good sound color and monochrome alignment on the fine tuning and all channels optimum fine tuning is in range of the fine tuning control...I would have liked to line up the osc so each channel is the same position on the fine tuning but that isn't easy especially with my body position effecting reception and affecting it differently on different channels...But it is good enough that it should work well on any VHF channel I'm ever going to pipe in to it and that's all that matters to me.

Last night I took a crack at making the UHF tuner work....it will tune in everything from 13-35 on one position of the UHF tuner and nothing elsewhere. Since I don't use a UHF modulator normally and only wanted to make the UHF channel indicator match the tuner position I decided to leave it alone.

I also removed the safety glass and trim and cleaned the rotten rubber gasket gunk off the bezel with isopropanol and off the glass with goof off. I then polished the bottom of the brass trim with brasso and steel wool and sprayed lacquer on it. I reassembled it upside down to hide some small dents and and minor color difference on the bottom. I may go back and hit a couple spots on the side which I notice more now that it is back together. I'll post some pics of the cleaned up trim/safety glass later.

All I need to do now is convergence and reassembly.
Once that's done I'll go back to my Moto 21CT2B and order the tubes the other CTC4 chassis needs and some slip plate to replace the silver foil that has peeled off it's CRT shroud.

That all has to wait for the folks to release me from work on the enclosure for our covid19 anti-starvation garden...

Electronic M
05-04-2020, 04:57 PM
A week ago Sunday I assembled it and tried to adjust the dynamic convergence...It seems like only the blue H amplitude control behaves as it should (vertical seems to be okay).
I decided that I'm not going to sort about the dynamic convergence being poor. I ran it through the whole Wizard of OZ and at the end installed the back it was then that the only 2 original capacitors (the B+ doubler caps) decided to fail so the next morning I changed them and then gave it another OZ run through (this time with a little less pointless letter/pillar boxing from my settings challenged Blu-ray player. The next couple of days I gave it some run time too. Last time I ran it green seemed too strong in the grey scale.... I'm eventually going to check the green video tube as I changed its B+ resistor to match the red tube and sams (it matches the RCA issued schematic) to try and improve green demodulation response.

At some point hopefully soon I'm to try to spruce up the Seville cabinet....After t tubes I need for the director chassis arrive I'll try to make the director chassis work better than the Seville chassis does then I'll pull the Seville chassis out of the director and try to have both my CTC4s working....

ohohyodafarted
05-05-2020, 01:23 PM
If your convergence controls are non-responsive, you may have to rebuild your convergence board. Those 100 ohm pots are notorious for wearing out. My Hallicrafter CTC4 clone that problem and after rebuilding everything it worked perfect. AS I recall there are 6 100ohm dual concentric pots. The carbon paths wear out.

Electronic M
05-05-2020, 01:56 PM
Yeah I'll probably be looking into that after this covid mess is over.

A couple of months ago I bought a fixed resistor kit that I pulled from for the Seville chassis and somehow up until yesterday I thought they were 2W parts...I double checked last night and realized they are 1W so I'm going to have to go back over the Seville and ID every 2W I changed and replace those with proper 2W parts. :stupid:

nasadowsk
06-04-2020, 06:26 PM
Not to threadjack, but anyone here have any ideas on what to do if the tuner's dead? My '4 is good up to the tuner now. But I can't get a darn signal from the antenna through the tuner. I *think* the issue is in the RF amp, but this thing s so stuffed with...stuff, that it's hard to nail it down. Naturally, RCA's literature isn't useful here. I tried resistance checks via Sam's, but that was inconclusive (I'll try again with someone to write the results for me.)

Any ideas? Also, what's the 'normal' agc voltage for this puppy?

Penthode
06-08-2020, 10:26 PM
Tuner problems are mostly mechanical and straightforward. Check first the tubes are lit and the prerequisite B+ is present. No signal the AGC should be close to zero volts.

Can you inject a signal to the IF input? Do you get snow? Has anyone tampered with the adjustments? Is the local oscillator working?

Post some more details as the problem should be easyy to diagnose.

Electronic M
06-09-2020, 10:33 AM
My working assembled set is not on the bench presently and has stuff sitting on it blocking me from opening it for measurements.

If you haven't already done so definitely clean the contacts in the tuner.

nasadowsk
06-12-2020, 05:53 PM
Penthode - I'm going to do a bit more probing here, stay tuned (heh) for updates...