I just acquired a CTC-5 :banana:

Pete Deksnis contacted me to say there was one available that "might be close enough" to me.

Well, it was about 200 miles away in Fort Wayne ...hmmm..
And a coworker hails from Indiana, and has relatives there ... hmmm
And his brother goes between northwest Indiana and Fort Wayne from time to time ... hmmm
And by the way, the owner, John Leone (not sure if he hangs out here) was GIVING IT AWAY if someone would only promise to restore it and let him see the result - :yippy:

It arrived yesterday, and I've only had time to remove the back and stare fondly at the chassis.

The attached pictures are from before it was picked up in Fort Wayne.
It's a Westcott Color Super Model 21CT785-5U, the last 5 meaning Mahogany and the U indicating UHF tuner included. There is a tag on the tube cap indicating the CRT was replaced on February 23 1962, but it also has the date code recorded as 6217, which would be in April. I can't see where to read the actual date code on the CRT. It reportedly worked when last turned on over 10 years ago. A quick inspection shows no obvious signs of problems, flyback looks good.

As you can see, it also looks intact with knobs and all.

First order of business will be a recap - if anyone has already created a list of required caps, I'd appreciate it, otherwise that's the first step for me.

I'll post some more "before" pix as soon as I can.

Thanks again to Pete and John, and Jim Laud, the transporter. :thmbsp:

Good on ya Wayne, really. :thmbsp: Gorgeous set.

Free! Imagine that. I'm a shade of emerald green only a CT-100 can reproduce.

;)

man and I thought I got lucky with my free CTC-11

What a beautiful set! Most excellent. I'm glad to see its in the hands of a collector who will care for it.

Nice CTC-5, I have the exact same model, it was my first roundie and I'll never part with it. I finally had DirectTV installed in the last month and have mine hooked up to it in my bedroom (main set is an HDTV rear projection in the living room.) I loved showing it to my girlfriend and telling her the set is over 5 years older than she is (and she's 44!).

Very nice, clean CTC-5. And the price was right. I owned a Westcott some years ago. I always liked that it was, for a CTC-5, a more compact upright console.

-Steve D.

Nice set!

Frenchy where have you been?


polaraman

So, let me get this straight . . .

A. You get this wonderful TV for free.

B. Someone delivers it to you for free.

Man, you must be livin' right :-)

Phil Nelson

I just acquired a CTC-5 :banana: ... First order of business will be a recap - if anyone has already created a list of required caps, I'd appreciate it, otherwise that's the first step for me.

Congratulations for this nice peace of American television history.

For me the first step is an inspection of the chassis and the crt. Check for previous repairs. Check for the correct tubes in their places. Check for burned caps, coils, resistors etc..

My philosophy of recapping is to replace only those caps which are absolutely necessary for proper working condition. I want to leave the set in nearly original condition as it is possible. I know that many people replace all caps whether it is neccesary or not. But this is not an intelligent choice. Many caps are not critical.

Note for designations: I have the RCA field data service sheet.

Next step: reforming electrolytic caps C103,104,105, see:

http://www.vcomp.co.uk/tech_tips/reform_caps/reform_caps.htm

I use a mains power supply with 0 to 350 volts in steps of 5 volts and measuring the current. Step by step with increasing voltage. Do not exceed 80 mA current in low voltages and 40 mA with high voltages.

Candidates for recapping: all coupling capacitors and waxies excluding micas and ceramics. Look for R C parallel, they are not critical. Screen grid caps are also not critical. Caps with a low voltage difference are also not critical. Those caps with a ! are a must. I recommend to check all caps with a ! first and then fire up the set and see what happens. While fire up, remove F102 and measure the d.c. current. This should not exceed 600 mA!

Power supply: C133 !,
PW600 (line oscillator): check C601, 602, 603.
Horizontal output and high voltage: C112, 115, 119, 120.
PW500 (vertikal osc. and output): C501, 504 !, 507 !, 508 !, 509, 510 !,
PW700 (color and video output): C714 !, 715, 731 !, 732.
PW400-A (video amp): C403, 132A, 132B.
PW400-B (blanker): C408 !
PW300 (I-F): nothing
PW200 (sound): C212 !
PW200-B (AGC, sync): C217 !, 222 !
Tuner: C116 !

Resistors: I found some resistors with increased resistance. But checking these is recommended when you have a raster or a picture.

Kind regards,
Eckhard

Oooooh ! I HATE you !! Free CTC-5, in GLORIOUS shape, free delivery...Oooooooh...Seriously, that is a gorgeous set...Can't wait to see pics of it runnin'...You are one lucky guy ! Also glad to see another veteran going to a very loving home, & not getting tossed.

Nice set!
Frenchy where have you been?
polaraman

Oh I'm always checking around in here! Hope to get my ctc-10 remote set set up in a permanent working location in the near future, I collect pinball machines too so never enough room in this tiny house to set up both tvs and pinballs. Have one b/w set set up and working along with the ctc-5 but the roundies take up a ton more room so I am in process of rearranging things around here.
Frenchy

Eckhard, thanks for the excellent detailed advice! I will be working strange hours this week and probably will not be able to make a thorough inspection until Friday.

Any hints on physically pulling the chassis, or is it obvious when you look at it?

- Wayne

Eckhard, thanks for the excellent detailed advice! I will be working strange hours this week and probably will not be able to make a thorough inspection until Friday.

Any hints on physically pulling the chassis, or is it obvious when you look at it?

- Wayne

From my quickly fading memory:
Remove the knobs on side and at front control box, remove control box (two screws I think), unplug shielded rca plug from tuner, unplug antenna wire from tuner, unbolt the tuner and it can then be bolted onto the rear of the chassis, remove the underside bolts, unplug the hv from the tube it's plugged into and remove insulator clip from cage lid, unplug the speaker at it's lugs. Watch it, this chassis weighs a TON.

The chassis is very heavy. If you want to operate the chassis outside the set with CRT connected, you should make an extension for the deflection yoke wires. You need an octal plug in and an octal socket for it. It is much easier to measure currents and voltages with the chassis outside.

Please check the cap numbers. I have seen that the SAMS and the RCA manual reported different countings for the caps.

BTW: last week I was in our newspaper with a report about the introducing of color television in Germany:

http://bs.cyty.com/menschen/e-etzold/archiv/TV/events/img/BZ_FarbTV22082007_2.jpg

After this report, I got a telephone call on last saturday. An old, retired engineer in a village 5 Kilometers far away want to give away his 1967 color tv set. I was sceptical and expected one of these heavy monsters. But what I got was a small, 19 inch color tv set with shunt regulator and a 490YB22 in excellent condition. The CRT has 1.1 to 1.2 mA on all three guns and the chassis is very clean without rust. I never found such a clean chassis of this period before. Here is a photo of this set:

http://bs.cyty.com/menschen/e-etzold/archiv/TV/siemens/img/FF12_inBetrieb.jpg

It is not a good photo, but you can imagine what it looks like.

Kind regards,
Eckhard

very nice

I have a Westcott and they are neat sets. I was noticing the legs on this one, they seem much shorter than the legs on my set. (Maybe a different production run?) The legs on my set are gold colored like on this set but are tapered getting more slender toward bottom. The legs on this set appear to be shorter and thicker...unles it's just me or an optical illusion. No big deal, this is a great set. Congratulations on getting it!

Gilbert

When I was a kid we had a set just like that. This was in the early 70s. Oure didnt have the legs on it. It sat right on the floor. It broke down a few times and my dad would tinker with and get it working again. He finally got tired of messing with it and got rid of it,probably about 73 or 74. It sat in the back of an old store building he owned for several yaers and then it finally got tossed. It would be nice to have it back now.
John

I have a Westcott and they are neat sets. I was noticing the legs on this one, they seem much shorter than the legs on my set. (Maybe a different production run?) The legs on my set are gold colored like on this set but are tapered getting more slender toward bottom. The legs on this set appear to be shorter and thicker...unles it's just me or an optical illusion. No big deal, this is a great set. Congratulations on getting it!

Gilbert

They are shorter than the picture in the brochure - don't know if they could be substitutes.

Here's a quick look in the back. I thought the flyback cover was gone - turns out it was stuck beside the chassis along with the screens from the bottom openings. For some reason, I didn't hear them bouncing around when it was carried in.

Can anyone tell me where the date code would be on this "Colorama" tube? Hidden under the yoke or cover perhaps?

Old_tv_nut-

I am going to be repairing a CTC-5 that I got from another AK member recently, and it does not have the flyback cover. Could you take a few pictures of just the cover for me while yours is off? I will need to make one for mine. Thanks for your help.

Chris

Here are views from each edge, and being installed - looks like it needs a long screw to fasten at the near left corner as viewed here.

Hi I see the cover from here.

Here are views from each edge, and being installed - looks like it needs a long screw to fasten at the near left corner as viewed here.
Thank you! I really appreciate the pictures. "14 views"-it looks like others have wanted to see them as well. :)

Just found this post,, very very nice set indeed!
Dan

Now for a littlle cold water - just drove 60 mi and back to borrow the CRT tester from DRH, and found out I shouldn't have bothered because the heater is open. (measures 180k ohms, actually - don't know where that is coming from). NO visible heaters when the tester is attached.

Has the tube gone to air? I can't tell - doesn't spark or anything when the tester is applied, but I suppose the tester voltage may be too low to do that.

Does anyone know if anyone is rebuilding metal cone 21AXP22A CRTs? (And is it worth bothering if it went to air, in case it has an air leak at the face seal?)

Tried knocking on the base a bit with no results. Anyone with experience that some other treatment (e.g. heating the pins?) might have success?

Anyhow, unless I could find a CRT, working on the rest of the set is not such a rush job anymore. :pity:

I'm sorry to hear that, truly a bummer. :sigh:

You could try heating the pins and dabbing a little solder on the ends so it wicks into the pin, I'm doubtful though in this case.

How hard is it to remove the yoke?
The getter is somewhere in that area, usually a ring of clear glass on the neck with the getter showing through.

Yes by all means try soldering the heater pins. I have had at least a couple of bad solder joints on the filiment pins. Heat it up with a 100 watt iron and let it suck some solder into the tip of the pin. If the original solder connection was marginal, it is possible that the heat of the tube combined with the heavy current of 3 filiments going through the pins, may have caused the solder joint to fail.

Hawkeye can rebuild it if it is under vacuum. He can not guarantee that it will be a success, because sometimes a metal tube will crack the face of the tube during the rebuilding. That said, another AK member has had Hawkeye do a successful rebuild of a 21axp22 and was very pleased with the results. I believe the cost is about $350 plus shipping.

Good luck and let us know what you find. Hope it has not gone to air.

If the getter flash still appears mirror-like, then the tube is certainly under vacuum. If it's milky-colored and is flaking off, then the tube is garbage.

Now for a littlle cold water - just drove 60 mi and back to borrow the CRT tester from DRH, and found out I shouldn't have bothered because the heater is open. (measures 180k ohms, actually - don't know where that is coming from).
I'm sorry to hear this news-the fact it is not infinity could be reason to have hope. Let us know how you do with pin resoldering, etc.

---

It sounds like you have a high resistance connection in the base. On several occasions I had to remove the base and re-tin the oxidated leads. Fred

Just curious, is the CRT base loose? If so, high resistance connection could certianly be the problem. One of the filament leads may have pulled slightly out of the plug, possibly when the CRT socket was removed. Hopefully thats all thats wrong.

Ok, I tried reflowing the heater pins - no change, still reads about 180k. Pete Deksnis told me the 21AXP22A included arc fixes - that may be the high resistance I'm measuring if things are shorted internally???

Took off the neck hardware and yoke, pictures attached. I can't recognize a getter area - is it the thin light band between the black dag ring and the large black dag area on the neck funnel? That area is cloudy and looks orangish if you shine a flashlight through from the bottom.

Haven't figured out how the plastic shield cone and CRT are mounted yet, see four clips but not sure if the shield can be removed by itself. Anyway, the chassis will have to come out first. Hope to see more at Doug's place tomorrow - he has one with the chassis removed already.

BTW, i am repeatedly wiggling and tapping after each attempted fix - the base allows a tiny movement when you try to rotate it, but the ohmmeter doesn't budge no matter what

The 21AXP22A arc fix involved a high resistance internal connection to the HV (bell), so that an internal arc woul be less likely to do any damage, and eliminated the need for an external resistor in series with the ultor connection. Probably unrelated to you filament problem.

Scotty at Hawkeye is (I think) willing to attempt a 21AXP22 rebuild, but I suspect it would not be cheap. If you hunt around in the collecting circles, you will likely find one.

The tube has gone to air, the white ring is supposed to be black and shiny.

The heaters no doubt burned up when it was powered up with air in the tube. :sigh:

With no further comments coming in, I've decided I will hold onto this set for maybe a year at most while hoping to get a usable/rebuildable 21AXP22A.
When I get to the point of finally giving up, then free to a good home, the same terms I received it on. Too bad the face seal can't be fixed. :sigh:

With no further comments coming in, I've decided I will hold onto this set for maybe a year at most while hoping to get a usable/rebuildable 21AXP22A.
When I get to the point of finally giving up, then free to a good home, the same terms I received it on. Too bad the face seal can't be fixed. :sigh:

Don't give up on this set yet. You have options. The glass 21CYP22 will work in this chassis with some slight mods. I believe many later 21" round tubes will also work in your CTC-5.

-Steve D.

Run some Wanted ads on the forums and on the ETF website. There is a good chance you will fina a 21AXP22 out there. And as Steve D says, you can always put a glass 21" crt in it.

Thanks for the encouragement! Not giving up yet, just trying to set some limits to get myself moving as much as anything else.

Old_tv_nut-

I am going to be repairing a CTC-5 that I got from another AK member recently, and it does not have the flyback cover. Could you take a few pictures of just the cover for me while yours is off? I will need to make one for mine. Thanks for your help.

Chris
Here is the "cheap and dirty" cover I made. Thank you again, old_tv_nut, and good luck on finding a usable CRT for your CTC-5.

my RCA has one just like that :D

nice!

The 21AXP22A is at Scotty's and it looks like the rebuild will be attempted this week. He waits until there are several days with no predicted bad weather, since a power failure would cause problems with the oven.

I am still seeing if I can verify a list of caps for replacement. Doug drh4683 gave me a complete list, but I am still trying to locate them all and make up my order, especially a nuisance since RCA and SAMS numbered things differently.

Meanwhile, all I have accomplished is to remove the chassis and the CRT from the cabinet. I plan to remove the tubes and check them.

Any advice on cleaning the chassis would be appreciated at this point. Can this stand up to a wet cleaning, or should I not risk it? I know that is how Tektronix scopes used to be refurbished, but they also may have replaced controls or other things that I wouldn't want to risk having to replace en masse.

Congrats! You have been most definitely blessed! Can't wait to see more pics. I hope all goes well on the CRT rebuilding, my fingers are crossed.. Personally, I wouldn't do a wet cleaning unless there is no other choice. It may take more time to detail clean but it is better safe than sorry.

Clean chassis with compressed air jet and mild detergent in water soultion and a tooth brush. I would NOT use any more moisture than is necessary to spot clean with tooth brush to scrub and dry rags to wipe clean.

Did you send the original crt that lost vacuum to Scotty or did you find a dud under vacuum?

If you sent the original athat lost vacuum I would ask Scotty to seal the glass to metal seal with Vacseal prior to, and after the tube goes into the oven. It is a long shot but may help your rebuilt crt to hold vacuum.

Good Luck and let us know how the rebuild went.

Thanks for the advice. I popped for the vac-seal. Scotty looked at the tube and thinks the face and neck seals look OK - he thinks it most likely that the leak was at the metal evacuation pinch off. Of course, there is no guarantee, which I fully understand, but I am willing to risk the cash based on a reasoned examination. If it doesn't work, it's back to looking for a dud under vacuum.
I think everyone involved has their fingers crossed!

We who have attempted 15GP22 rebuilds have our fingers crossed for you!

[1] Fingers are crossed...

[2] Yes, there's something unseemly about a stream of water under pressure cleaning a valued chassis, but there have been no negatives for me so far, and I use it just as a first step before the hands-on cleaning and polishing.

Drying the wet chassis is important and I always use some combination of:

*wiping it with a cloth

*making sure the day is hot, sunny, and dry to 'bake' out the moisture (turning occasionally to get all sides and the bottom)

*and using a leaf blower to remove standing water and 'blow dry' the beast (this is the best way to remove moisture from hard-to-reach cracks and crevices).

Pete

I too use the hot water/pressure approach to cleaning a chassis. The only thing to be careful of is cardboard and paper. I've found that if the chassis is dried thoroughly, parts won't be damaged.

So for the cardboard and paper do you just wrap them up the best you can, or just avoid them? My 63 Zenith is pretty dirty looking, lots of dust. My 53 B&W Zenith is alot cleaner.

We who have attempted 15GP22 rebuilds have our fingers crossed for you!

Scotty showed my some 15GP22s with obvious leak points - they look like filaments of air crossing the seal surface from outside to inside when you look from the front. Some tubes had a lot of them. No such obvious defects on the 21AX. He also tried a spark coil to see if he could get any sparking through the glass.

Testing tubes in the CTC-5, using a Realistic model 108.

I'm getting suspicious results on the 12AT7 color demods. The tester table says to use a quite low setting (4) on the "D" dial, which means a low reading for a given amount of current; that is, the tester expects a lot out of these tubes. Anyway, both demods read really low unless I increase the setting (I tried this because one of the types that could substitute requires a higher setting). Also, the reading jumps to a peak value when the button is pushed and them fades to lower values (easier to see if the "D" knob is cranked up).

Any ideas? Something wrong with the tester? A mistake in the settings table? I have tested about half the tubes and the 12AT7s are the first ones to behave this way. Found one dead 5U4 rectifier, otherwise the other tubes behave reasonably.

well, I found a couple of 12AT7's I bought last year for another project, and they test out OK! So, both in the CTC-5 were fried - must have made the color a little weak - but with the CRT dead I suppose it was dark too. So much for that recollection of it "working the last time it was turned on" :p:

Testing tubes in the CTC-5, using a Realistic model 108.
I am amazed to see that Radio Shack once made an item like that. Times sure have changed, so much. Even as of the mid-70's when I started going to RS often and bought plenty of their kits and parts, I don't think they had anything close to a tube tester for sale.

Well, bad news on the rebuild of the aired 21AXP22A. Despite liberal use of Vac-Seal, and Scotty's optimistic examination of the aired tube, it did not achieve a good vacuum. Scotty reports that the gun looked OK after evacuation/baking (indicating not much air if any), but the getter flash looked abnormal, and now the tube shows internal blue glow under test. So, there's some unidentified small leak.

I'll be driving out to see it and retrieve it on Sunday. At this point it's not worth a second try without knowing where the leak is and whether it could be sealed for sure.

Sorry things are not going well, the set is worth the effort though. Hopefully you guys can figure it out or find a good AXP somewhere.

Oh dear. That IS bad news. probably does not bode well for the leaker 15GP22s, but then again, who knows? We still intend to attempt a leaker 15G, possibly on our next trip to Hawkeye.

At this point it's not worth a second try without knowing where the leak is and whether it could be sealed for sure.On the bright side, let's hope there's a possibility of gaining valuable insight as to how early roundies leak.

Pete

To follow up on Petes suggestion, Wayne, you should ask Scotty if he can use his sparker (high voltage AC power supply) in an attempt to isolate where the leak is in the 21AXP22. Maybe this could lead to some insights.

To follow up on Petes suggestion, Wayne, you should ask Scotty if he can use his sparker (high voltage AC power supply) in an attempt to isolate where the leak is in the 21AXP22. Maybe this could lead to some insights.

He has tried it, but we will try again. I'm driving out tomorrow and will see Scotty on Sunday, so I'll have an update hext week.

Here are a couple of pix of the tube at Hawk-Eye. Scotty and I jawed a bit, and he's willing to house it for a while in case the geniuses here (you know who you are) come up with more ideas. Scotty didn't apply Vac-seal to every possible place, plus there may be other things we could do, so thinkin' it over.

The close-up with the Tesla coil shows the "blue glow" (photographs more pink) due to residual air. Scotty says the leak is big enough that he can notice a change over the last 2 days. Eventually, the HV will just make arcs between the electrodes when enough air gets in.

Scotty didn't apply Vac-seal to every possible place....Just curious: cured vac-seal is evident at the glass-metal interface in your photos; did Scotty also vac-seal the faceplate?

Pete

Just curious: cured vac-seal is evident at the glass-metal interface in your photos; did Scotty also vac-seal the faceplate?

Pete

I thought so too, but Scotty said he only did the faceplate, not the bell.

Now a question on what to do in the meantime -
What does it take to replace the metal-cone 21AxP22A with a glass 21FBP22? Can anyone describe a good way of mounting a glass tube, preferably in a way that would allow going back to the original should one appear?

I can imagine making a cradle out of straps of some kind, but if the shroud has to be removed, I'm not sure how the yoke should be supported. With the factory setup, the yoke is actually clamped to the shroud, not the neck.

Sorry for the late reply, I've been working on my own computer system hard drive diaster since the 1st of the month. Lost all my Healey and 21CT55 photos so can feel Wain's disappointment with the CTC5. I replaced the 21AXP22s with 21FBP22s in my CTC4 and CTC2B in early 1960. They are both mounted the same with four struts running from the yoke assembly to the cabinet front structure. The 21FBP22's glass envelopes were wider than the metal coned 21AXP22s so the plastic insulating shroud had to be cut away from its front mask bell and the struts had to be lengthened and remounted to the cabinet's front wooden structure. I used screw-eyes screwed directly into the wooden front. Since I'm not a restorer, this hack was fine with me

I realize the CTC5 uses the plastic shroud to mount the yoke assembly and support the CRT. If it can't be modified maybe the strut and screw eye scheme will work for you. What do 21FB's sell for these days especially the rare-earth A version? Replacing the 21AX's with the 21FBs is the way to go, you won't be sorry..........Tom

One disadvantage of replacing a 21AXP22 with a 21FBP22 or other all glass color CRT is that you give up the superior colorimetry of the 21AXP22s phosphors.

Interesting adaptation. I also have received pix of an original RCA kit, which is somewhat different, and includes a plastic back plate for the yoke so it can be clamped and supported on-center by the CRT neck.

I don't want to hack up the cone, in case I would get a 21AXP to install later. Also, as John Folsom says, one of my main reasons for restoring the set to operation is to look at the color rendition with the original tube.

Any mechanical engineers want to join this project?

I'm new to this, so I'm not very familiar with how this board works. It seems there're a lot of very knowledgable folks here. I have an RCA CTC-11. Has run well for many years with easy fixes (replace a tube here and there, etc.) It's starting to need some caps, etc. And I'd like to replace the flyback. Where is a good source for these parts. Also, does anybody have the service manual or any service information for the CTC-11. Thanks. Dave

Hi Dave,
Welcome to the forum, It's always nice to see another TV guy join the group. I'm sure someone here has what you need. But, it would have been best for you to have started a new thread about your issue. No biggie though, I made some REAL goofs around here when I first came, still do sometimes.LOL. So, that said, just start a thread about your 11. I would like to see pics. Also, look up Moyers electronics. They might have a fly for you. Try JustRadios for caps, they are reasonable and have a good product.
Mark

I don't know how to start a new thread. I'll try it now. I guess I have to give it a title. I'll try "RCA CTC-11."

Mark:

Thanks very much. I think I was successful starting a new thread. I still don't know how to navigate well. I have pics but I don't know how to post them yet. I'll do it under the new thread when I figure it out.

Thanks, Dave

Update - I've got dibs on a 21FJP22 (glass tube), but I haven't quite figured out how to mount it. I got info on how the factory mounting kit worked, but it involves a mounting adapter for the yoke that I'm afraid I couldn't duplicate. I also got info on modifying the existing insulating cone to mount the glass tube, but I don't want to hack it up, just in case I might get a working 21AXP22A in the future. So, still scratching my head a bit. I found a 17-inch diameter poly funnel on ebay that might be possible to cut down to make a mounting collar, but it wouldn't hold the yoke.

Meanwhile, I have ordered some replacement small tubes, film caps to replace the paper caps, and new 'lytics. It's moving slow, but moving.

I wonder if a newer 21" yoke would be compatible with that chassis? I would think someone would have a spare sitting around, something from a CTC-11-16. I don't know that they changed them up any over those years.

i have a nos yolke for the later roundies. steve

i have a nos yolke for the later roundies. steve

sent you a PM

Update - I picked up the rebuilt 21FJP22 over the weekend. Now taking a good look at how I might mount it. It's less a question of knowing what I might want to do and more of how I can do it myself with nothing in the way of shop tools. I would not like to do it the way Tom did for a couple of reasons:
- The existing yoke mount is part of the poly cone in the CTC-5, not metal like Tom's pix;
- The example pix I have of a CTC-5 with factory kit show a metal shroud that is near the face of the tube and therefore away from the HV connector.

The shroud, which apparently is what holds the tube to the bezel, has four metal tabs that are screwed to the existing mount points for the 21AX, so the tie rods are not needed. It also has the yoke supported by the neck of the tube, so it seems the support by the cone is not needed. I tried the yoke on the 21FB neck, and while it's slightly loose, it seems like a small bit of shimming will fix that.

Now my problem is to figure out how I can fabricate the equivalent of that mounting kit.

Of course, if a good 21AXP22A would show up..... :)

Still working through cap replacements - replacing paper/wax caps with film types.

I got to the .047 600V that is across the line. I know this needs to withstand whatever mother nature and the power company might throw at it, so I'm wondering what exactly to use to replace it. Any suggestions?

I no longer replace the power line decoupling capacitors in sets. I simply remove them, along with any resistors from line to ground. I have not found operating old sets without these components causing any problems. This also seems to reduce the mild shock hazard this connection from line to chassis provides.

Still working through cap replacements - replacing paper/wax caps with film types.

I got to the .047 600V that is across the line. I know this needs to withstand whatever mother nature and the power company might throw at it, so I'm wondering what exactly to use to replace it. Any suggestions?

If you decide to replace it, go to www.justradios.com. They sell "safety capacitors" that are designed for this purpose. Of course, you could try the set without it, like has already been suggested. I've got many radios from the late '20's and early '30's with no line bypass cap and they seem to work just fine.

If you decide to replace it, go to www.justradios.com. They sell "safety capacitors" that are designed for this purpose. Of course, you could try the set without it, like has already been suggested. I've got many radios from the late '20's and early '30's with no line bypass cap and they seem to work just fine.

Thanks for the link - I just took a look and also will check them out for any others I'm missing.

I don't know squat about vintage tv's except those I grew up with... but man that is gorgeous!!!

I just came across an ad for a 1964 Heathkit roundie, which gave me the idea that the construction manual might be a good source for an idea on how to mount the 21FJP22 in my CTC-5.

Any ideas where I could find a manual?

Looking at the RCA field service guide, I see there are diagrams of the CRT mounting for the 21CYP22 with it being held in place by the magnetic shield. However, although it mentions padding, it doesn't give any details, because in replacing the tube you would just use what was there from the factory. So, I know some more, but I'm still left scratching my head on how much and what kind of padding and where to put it.
The CTC-11, which is the first using the 21FJP22, has similar mounting, but padding is not even mentioned. CTC-12 and later use a mounting strap and special brackets that grip the edge of the screen. I don't think there's any way I could safely duplicate that.

OK, now I need some advice. Will be firing up the recapped chassis soon, and need to know what I can do with it disconnected from the CRT.

I think the yoke has a jumper wire that disconnects the power to the horiz output and maybe the vertical when the yoke plug is pulled. Correct?
Do I need to also pull the H output tube or anything?
What else doesn't work with the yoke pulled? AGC (due to loss of gating pulses)?

Thanks for any guidance here!

You need to connect a resistor to "absorb" the current normally drawn by the horizontal sweep/hv section.

From the Sams PF #358: "The high voltage should be disabled by removing the fuse (M3). Connect a 2500ohm 100 watt resistor from B+ side of C2A (filter capacitor) to chassis". That should do it.
Any suggestions from other members?
kEVIN

I do not recommend the resistor loading technique called out by RCA. It is an enormous bother with no real advantage. Much easier and better to just put the yoke on the bench along with the chassis and fire it up. This allows all the gated circuitry (AGC, color burst, color amp, color killer) to function normally. I take the loose end of the HV cable and insert it into a glass jar or drinking glass, and tape it in place. This insulates the end of the cable and makes the set safe to operate on the bench. This way, all the functions of the set are operating, and comprehensive fault isolation and troubleshooting can proceed.

Having everything working sounds best to me - have to be careful anyway, so the HV thing is doable. Not having the required 100 watt resistor clinches it.

Finally got the nerve to fire up the chassis, and I'm getting sound from the speaker, with no apparent overheating. Just using some clip leads for an antenna. Let it run a half hour. Power transformer is cool so far - worried me a bit because I found some brown stuff(wax?) had dripped out the bottom onto the wires. Flyback primary is a little warm, secondary is cold.

Still havne't figured out how to make a shroud-type mounting for the glass CRT - more head scratching to come.

Onward!

I have some of that stuff oozing out a bit from the bottom of my power transformer too. I think it might be ok though, I think a lot tof them do it. There is also a bit dripping from the one in my 9. Just keep an eye on the temp.

The power transformer in my -5 lost a lot of wax, too, but it hasn't given me any trouble and doesn't seem to be losing any more. Not many sets put the transformer in a box like that.

The power transformer in my -5 lost a lot of wax, too, but it hasn't given me any trouble and doesn't seem to be losing any more. Not many sets put the transformer in a box like that.

Yep, I've only seen them in RCA color sets but are probably found in a few others. I wonder why some leaks out and then it is fine? Maybe it did it when the transformer was new and it stops when it is broken in. I'm glad other people have seen this, I was a bit bothered by it at first.

Thx for the FAQs on wax

Tonight I chased down the horizontal waveform and hold adjustments, which interact a lot. I now get a solid horizontal lock and can adjust the AGC for the specified 2Vp-p detector output. For some reason, the p-p amplitude at the video output is low (plenty of blanking, and the brightness control works, but max contrast seems anemic on the scope), so more trouble shooting remains.

I hooked up a color bar DVD tonight, and it appears the video output is OK after all - I'm getting the peak-to-peak reading specified in SAMS, although it's lower than I guessed it would be. Also, the color circuits locked right in and are producing classic-looking waveforms on the G1's. :yes:

Also, the vertical hold seems to work OK.

I checked out the action of the contrast control, and I can see why there is a suggested change. There is quite a bit of quiescent current in the video output tube, which is changed by the DC coupled contrast control setting. This results in wide swings of black level (brightness) when the contrast is adjusted. The change to capacitive coupling will eliminate the DC shifts.

I have got to get the CRT mounted somehow now, because it looks like the chassis is fully functional.

Hi - "Chuckles" the TV restorer here--

Today I put in the contrast control fix (see attached diagram). However, I didn't study it very carefully and just wired it as shown. If you pay attention, you will see that this reverses the action of the contrast control, so max contrast is now counterclockwise. I plan to leave that way, as the chassis is very crowded in that area, and completely disconnecting and rewiring it seems like asking for trouble.

The contrast control now acts like it should, without the huge shift in DC level - should be much easier to set up and adjust the background controls now.

A second look at the color controls inidicates that the hue is not centered - more work.

By the way - anybody have spare tube shields? I'm missing a couple.

I have at least a shoebox full. If I can remember Sunday I'll dig out some clean ones. Drop me a line with your address. Enjoyable to read the progress!

I have at least a shoebox full. If I can remember Sunday I'll dig out some clean ones. Drop me a line with your address. Enjoyable to read the progress!

email sent!

"...and the smoke it encircled his head like a wreath..." - no, not Santa, but me, wondering what that smell is - something died suddenly in the tuner (although I didn't realize it for a few seconds, because I was working on adjusting the chroma oscillator, and thought at first I killed that) but it turned out to be the B+ dropping resistor on the tuner. Now I'll have to track that down. The burned resistor is supposed to be 1k/2W, now measures 270 ohms. A secondary dropping resistor that should measure 6k (6.8k in parallel with 56k) now measures 1k in the circuit - I haven't figured out where the parallel path is, if any. But all the B+ points measure about 2M to ground, which they should - no shorts evident!

That's enough geeking around for Christmas Eve - heading for some eggnog and carols on TV - Merry Christmas all.

Oh - and thanks to Brian for the tube shields - just the assortment I needed.

I finished the mods to mount the glass CRT (21FJP22) today. Steve McVoy provided a complete set of mounting hardware from a junker CTC-7 (intended for the 21CYP22, which has the same shape as the 21FJP22, but a different anode connection location).

Thanks, Steve!

It turns out that this hardware fits the CRT perfectly, but is exactly wrong for the CTC-5 bezel. For example, the CRT rim insulator is corrugated just enough to prevent it fitting in the CRT well molded into the bezel. Also, the metal shield, while it looks similar to the shield in the RCA adapter kit, is actually just the same size as the CRT well, so doesn't fit either inside or outside. Since the manual says it's not used in metal cabinet sets, I know it's only purpose is magnetic and not structural. Therefore, I did the CRT mounting without it, and will cut it as required to mount it over the other hardware.

Despite the mismatch to the bezel, it was possible to use the mounting ring by extending the bolts that are built into the CTC-5 bezel. This saved me from what would have been a difficult construction for me. After I extended the bolts, I called a friend to see what I had done (before standing the set up), and he suggested that the bolts would probably bend and let the CRT shift if not supported. Fortunately, I had bought one of each kind of padding material offered by American Science and Surplus, just in case I needed it, and the foam rolls you see did the trick.

The anode button is a bit close to the mounting ring, but I plan to use silicone grease and also to put the smaller rubber insulator from the CTC-7 between the HV cup and the ring.

Now, I have to find and fix whatever burned the B+ dropping resistor for the tuner, and work towards pictures!

Replaced the burned resistors on the tuner today. Couldn't find any particular cause though - guess they just got tired.

Then I almost got into trouble trying to align the color oscillator drivers to see if I could get the tint control centered better. At one point I stuck the tool into the bandpass transforner by mistake and really messed up the tint. Then trying to follow the instructions, I found that the so called "touch up" of the drive transformers actually could move the tint by 90 degrees, that is, tuning for the peak demod current according to the instructions, (R-Y) was coming out of the (B-Y) demod, and minus (B-Y) out of the R-Y demodulator. Anyway, after wasting an hour, it's now back to normal tint. I probably should be doing a complete IF and color bandpass alignment, but I'm going to move on to more basic things like hooking up the HV and CRT dag grounds and installing the chassis. Then I'll see if I basically have a picture and sync instead of just scope traces.

Started to install the chassis and only got as far as you see, because the clever (?) bolt extensions and mounting pads I put in for the glass CRT interfere. Second pic shows the vertical tube about to be decapitated.

Back to the drawing board :worried:

Still, it was a pretty clever idea and you've made a lot of progress. Keep the faith.

John

Take a hacksaw and cut those bolts until the straps fit perfect.
Move that padding towards the face of the tube for support.
You have the pads on cone, not good, the glass in that area is very thin.

Also, if that edge purity magnet assembly is in the way, you can remove it when using the 21FBP22. I would take it out and save it with the other stuff in case you find an AXP. Mine is removed for cleaning right now and that is where I got the idea. Just a thought....

Take a hacksaw and cut those bolts until the straps fit perfect.
Move that padding towards the face of the tube for support.
You have the pads on cone, not good, the glass in that area is very thin.

Making the bolt extensions shorter will not work, because the bolts in the CTC-5 come out of the bezel at right angles, whereas the straps are made to mate with bolts that are angled.

However, thanks for the suggestion, and please continue to make suggestions if you think of anything. The best thing may be to make new, longer straps.

Also, if that edge purity magnet assembly is in the way, you can remove it when using the 21FBP22. I would take it out and save it with the other stuff in case you find an AXP. Mine is removed for cleaning right now and that is where I got the idea. Just a thought....

The edge purity magnets were a little annoying when screwing on the bolt etensions, but not an impossible block. They may be redundant, though, as the bumpers with "hairpins" on the CTC-7 mounting ring are described as edge purity magnets.

I am definitely saving all pieces I remove!

If I could adapt the metal shield to hold the CRT, it would be more like the RCA adapter kit, but it has no mounting tabs, and as I said above, it is exactly the same size as the CRT "well," so it won't fit either inside or outside. Cutting notches and flaring it would probably work, but I'd still have the problem of attaching some sort of mounting tabs.

Still noodling, but maybe the best bet is to take the mounting ring to a metal shop and have them duplicate the straps, but 4 inches longer and with ends angled perpendicular to the face.

Edit - I really appreciate everyone trying to come up with some ideas.

I poked around the hardware store, and ended up making a hinged bracket out of two brass L-brackets. I used these for the bottom mounts that interfere with the chassis.

For the top mounts, i reduced the padding and moved it towards the CRT face, as was suggested earlier. I removed the edge field-compensation assemblies, aslo as suggested earlier. You can see that the hinged bracket fits quite well on one side, but since the holes as supplied are offset, doesn't clear the existing boss for the field-compensator on the other side, so is cocked a bit.

I tried to bend one of the ground contact sprihgs that grounds the pencil box to the chassis and also stops full forward placement, and broke it. I think one will be enough, though.

You can see that I am very close to making contact between the CRT and couple of tubes. I also included a picture of the alignment on the right side (viewed from rear) chassis mounting. You can see it's barely clearing. The left side does not clear with the tubes just about to hit the CRT. However, the controls seem to extend enough through the pencil box with this position.

Plan:
1) give it a rest for today
2a) drill/enlarge mounting holes in cabinet;
2b) arrange some sort of stop to prevent the chassis sliding too far forward
3) cut down the tube shield that is almost touching the CRT

here's the pic of the tube near-interference

Looks good Wayne, getting much closer. I would try not to drill the cabinet at all as much as possible. Can you bolt it in where the controls will just fit? That tube getting close shouldn't hurt anything. I would just cut the shield if it don't fit.

The problem is that the left side holes don't line up at all (I think they're off by just one diameter), and the unshielded vert tube on the left cannot go further forward. I don't think enlarging the holes in the plywood base and shimming to keep the chassis from going forward the extra 1/4 inch is a big deal. I just want to be able to move the set without having the chassis slide around and hit tubes against the CRT or straps. As you can see, the mounting holes had some slop anyway, which was OK before, but needs to be tightened up now. As long as the control knobs fit, the chassis could stay in the new position even if I got an original CRT to install at a later date.

Ahhh, I see what you mean. I am looking forward to seeing her up and running. This has been a long project with many obstacles to overcome. Should be very worth it in the end though. Good luck Wayne!

Today I took a look at the mounting and decided maybe the chassis would just barely fit - and it does.

Here are the pix of the first light on the rebuilt 21FBP22.

#'s P1170014s, -018s, -019s at power on with no adjustment whatsoever.
The other three (next post) after some adjustment.

Three pix after some adjustment.

Problems:

Insufficient width (plenty of height)
HV regulation isn't working very well - size changes somewhat with contrast, can cause pic to bloom at max contrast - need to jmeasure
Focus at one end of range
Poor H lin - should I tweak drive waveform?
Blue H dynamic convergence out of range /not doing much
R/G V dynamic covergence going to end of controls
[need to investigate position of neck hardware]
Purity not perfect, but will work on that after Horiz problems are fixed
60 Hz hum in audio
Some 60 Hz hum in horiz (size or phase?)
Forgot how much V hold, V size and V lin interact on these old sets!

Way to go Wayne! That set is coming along nicely. You might try replacing the HV rectifier, focus rectifier, HV regulator, and damper tubes and see if this improves your HV performance. The only reliable way to check the HV tubes is in circuit. Thanks for the photos, and keep us posted!

I did check all the tubes in this set on a tube tester, and replaced those that measured weak. But testing in circuit is a good idea now that I have everything running.

By the way, I need to rig up a ground lead for the CRT - I'm just using a clip lead to the mounting strap, which has a dag contact spring. Hypothetically, there is a ground path from the dag to the strap to the mounting bolts to an existing ground wire, to a bowed contact spring in the front of the cabinet (the one remaining after I broke one -see previous post) to the chassis. However, the chassis contact spring is a bit rusty, and the contact is poor to non-existent. Need some sort of clips that could clip onto the mounting strap on one end and the chassis on the other.

**Any hints about the width and H linearity would be greatly appreciated. I do have it on a variac and line meter, tried raising the voltage a bit, but that is not the fix.

Turned it on and let it run for most of the afternoon to see what would drift or smoke.
Vertical height, linearity, and hold all drift for the first 30 minutes. Horizontally, it started out with a bit more width, but within a few minutes was back to the same narrow picture as yesterday. Focus is still at one end.

Played with off-air signals (amplified rabbit ears, admittedly suboptimum for this location), found tremendous variation from station to station, especially in color level.
Of course, everthing interacts, but the fine tuning is especially a nuisance. Tuning to the supposed optimum point (just below sound interference in the picture) reduces the sound volume. So, the sound detector must be sensitive to the intercarrier amplitude. Found that the hum/buzz in the audio depends on video content, so this is looking more and more like a complete IF alignment.

Checked out the UHF (won't have any after Feb 17), found it will not make snow through the whole frequency range, so there may be some AGC or other problem.

Went through the background and G2 (screen) adjustments. Could not get the DC reading I'm supposed to on red G-K as a starting point (115 V max, instead of 130). It does make a B&W picture, though for all settings of brightness and contrast.

I think the B+ is OK (by measuring video output voltages), but I didn't find an easily accessible point to measure with the chassis in the cabinet.

Blue dynamic convergence controls seem dead. Red and Green seem to be lacking range. Adjusting convergence coils position didn't seem to make much difference.

Played with purity and improved it, but now horiz centering is at one end and would like to go further.

I will measure the HV at some point, but I found that the convenient lead on my HV meter is just too big in diameter to go in the connector in the HV compartment, and can't be squeezed small enough. Have to rig something.

Need to revisit the AGC setting, turning it down a bit from max improved the color transient response, but makes the picture dim at max contrast.

Now I'm musing whether I will need to replace a bunch of resistors in addition to the recapping.

Well, at least no smoke so far -- As my relatives used to ask me, "When do you think they will perfect color TV?"

Not a totally unfamiliar pile of issues! What can I offer? I actually think HV is pretty easy to measure on these, at least with the probe I have, since the whole metal base of the HV rectifier socket is at second anode voltage. Just stab it in there somewhere close.

I've had trouble with some convergence controls not seeming to make much difference. I haven't dug that far.

I haven't had width problems; I have the control set at the highest of the 3 settings. Before I buttoned everything up last time I adjusted the vert & horiz lin for a very nice circle in the middle of the screen but now it's all distorted again. That didn't last long. Things on these sets seem to vary a lot with voltage, time or ??? I have also noticed, clearly, the difference in color & brightness from station to station. I know this was a selling point in later color sets, so I guess this was seen as a major shortcoming to some folks. You can wear that tint control out while channel surfing! This is proof that not all the improvements in color tv were in consistency at the station. Even today these sets struggle. That's okay...gives them "character"!

For the grounding strap, can you do something with a long, thin spring? Lots of sets used something like that. Hardware store should have a selection.

Thanks for the info, Bryan.

For the ground, I was thinking along the lines of "speednut" u-clips on the ends of a wire. But I have to think about a flat spring mounted on the chassis - might work and be simpler!

Now for a little begging:

Would anyone have a blue lateral magnet laying around? [HA!] The one that came with this set is partially broken (I think). The magnet part was held in place with electrical tape and is really loose (seems about to fall out), making it tough to adjust and leave adjusted without moving it. Or maybe they're all like that, in which case, never mind! If no one has a spare, I'd still like to see what a good one looks like.

[QUOTE=old_tv_nut;2419985]Thanks for the info, Bryan.

For the ground, I was thinking along the lines of "speednut" u-clips on the ends of a wire. But I have to think about a flat spring mounted on the chassis - might work and be simpler!

QUOTE]

Where did you get that picture of all the different tinnerman nuts? Looks like a good supplier we all should be made aware of.

Sorry, didn't save the URL -was just looking for an illustration. A quick search shows lots of places, but I can't find that one again.

Sorry, didn't save the URL -was just looking for an illustration. A quick search shows lots of places, but I can't find that one again.

Thanks, I just found it. Fastener World Inc.

http://www.fastener-world.com.tw/upload/prod_item/m_000359-1.jpg

Unfortunately they are Taiwanese. I was hoping it was a U.S. retailer. Looks like they have a good variety of hardware.

Thanks, I just found it. Fastener World Inc.

http://www.fastener-world.com.tw/upload/prod_item/m_000359-1.jpg

Unfortunately they are Taiwanese. I was hoping it was a U.S. retailer. Looks like they have a good variety of hardware.

Sorry, I linked the wrong image.

http://www.fastener-world.com.tw/upload/prod_item/m_000359-3.jpg

Got the replacement horiz output tube today. It doesn't look like the one that was in the set (it looks bigger). It cured the lack of size and high voltage regulation.

Even though the convergence problems and etc. aren't fixed, I couldn't resist putting the Rose parade DVD on and taking some pix.

I set up Vert size and linearity first, but they drfited over about two hours of viewing, as you can se in the test pattern pix, which I took last. Also, I had the chroma a bit high. After about an hour, I noticed that the black level seemed to have drifted upwards a bit, so I turned it down a little. However, the lack of 100% DC coupling is also apparent, so it may have been due to the changing light during the parade.

Those pictures look quite good. Just a bit more tinkering with the convergence and you will have an excellent display.

I have to dig into the convergence deeper. I plan to do some snooping with the scope to determine if some waveforms are just too low in amplitude or missing entirely.

Can someone with a CTC-5 tell me what kind of screwdriver works on the second tier of controls? I forgot to note what they are before installing the chassis. I can work the inner and outer first-tier controls with small and large screwdrivers, but I am poking around in the dark on the second tier and can't seem to find them with the small screwdriver.

Another thing I noticed on the closeups (see the 5th picture) is a variation in the hue or color balance (look at the talent's chin and upper neck). At first I thought this was a purity problem, but it only appeared in these closeup shots. Now I think it might be the burst gate picking up some of the video on the left edge, so the greenery or something is being seen by the color sync circuit.

Those coils take a pretty small screwdriver; they can be tough to find, and even tougher to keep the driver in the slot while you are making adjustments. There are wires that sometimes poke up and get in the way, too, so you may have to push them out of the way.

Thanks Bryan - definitely have encountered the wires

Wayne, seems the major part of the CTC5 restoration is completed, looking good! My Dad's CTC4 of 50yrs ago was my first adventure into color TV and was the first narrow-band chroma RCA made after the CT-100 based 21CT55. It used the same 21AXP22 but had at least 10 less tubes. I recall that the CTC5 was designed to eliminate some of the CTC4's worse problems but it remained narrow-band. Did RCA or any other tubed roundy maker return to the original NTSC wideband, low level chroma demodulators?

As you continue refining your CTC5's picture quality, please continue posting your screen shots in the highest resolution. I use DVD test disks to evaluate all my CTVs and compare their PQ against the highest performance modern ss CTV that can be accommodated in my tiny lab. My favorite DVDs are "Digital Video Essentials" and "Planet Earth". Obviously the goal is to get the TV being evaluated to produce the closest PQ to the "Lab-Standard" PQ and capture the comparisons with a quality digital camera in JPG format....Tom

I can't refer to the other "COLORTRACK 2000" receivers, but the CTC-133B (1985/86) is a wide :yes:band receiver, using IC's made by NEC of Japan, utilizing IQ demodulation. The CRT seems to produce better reds than some of RCA's previous models. I have a copy of this chassis, and it is a very good performer as far as color reproduction goes, but is does not produce what I would call a bright picture, perhaps due to the choice of more accurate phosphors at the expense of brightness. The only trouble I have had with it is a failed audio chip, and an open resistor on the CRT board, both easy repairs.
I have a CTC-4, CTC-5N, and CTC-7. RCA specifies "X and Z" demodulation in the deluxe CTC-5N, and subsequent chassis, which is , I believe, narrow band demodulation, although with improved circuits over the model years. All can produce excellent color pictures, within the limitations of their design, as can the CTC-5 Special, as has been demonstrated on this forum.
Kevin

Did RCA or any other tubed roundy maker return to the original NTSC wideband, low level chroma demodulators?



Tube demodulators actually came in three flavors in terms of bandwidth. The original I/Q demods in the CT-100 were of course low level and of greatest possible bandwidth.

Demodulators that went directly to the CRT grids (like the (R-Y)/(G-Y) in the CTC-5 "Super chassis) were probably the narrowest because of needing high load resistance to get the necessary gain in a single stage. The X-Z were somewhere in between. They could not have too much bandwidth, or they would show bad color edges due to I/Q quadrature crosstalk; but they would not be so limited by the capacitive rolloff, due to having some gain in the demods and some in the matrix amplifiers.

I am quite familiar with the 80's attempt at I/Q demodulation in the RCA solid state set, as I studied it closely while looking at the possibility for widebanding at Zenith. The fact is, creating an IF that passes the chroma without introducing phase distortion of the upper sideband can be quite difficult (although surface-wave IF filters could probably be designed to do it). Unfortunately, RCA did not succeed, and the high-frequency I channel gain on that set was so low in order to hide problems that it did little to improve the chroma resolution. It could fairly be said to be present in the set for advertising purposes, but that was about it. It's too bad, because some very clever design went into the analog color chip to minimize pin count while sitll providing the required I-channel delay line. It is one of my favorites. The designers came up with an amazingly clever way to drive and sense the delay line with a single pin! However, when we put the set side by side with an equiband Zenith (which had a very simple color takeoff with a very gradual rolloff), the effect at normal viewing distance was nearly indistinguishable.

As part of this study, I determined that part of the problem with achieving good I/Q results was that the transmitter Q filter was under-specified by the NTSC. In order to completely avoid the sideband crosstalk, it should have had a trap at 910 kHz, corresponding to the sound carrier offset. then the lower Q sideband would be curtailed the same as the upper sideband. Without this feature, some encoder Q filters that met the NTSC spec still would produce significant energy at 910 kHz, and this would be visible in the I channel.

Another way to avoid this crosstalk that cannot be done in a 6 Mhz channel is to have the full upper chroma sideband available. You can do this today if you have an I/Q set with a composite or S-video input fed from a wideband source, like a DVD player. In the lab experiments I did, we went through the whole sequence of comparing direct RGB to baseband YIQ to composite YIQ, to RF modulated YIQ to determine at what points the degradation occurred.

Another thing we determined is that even proper YIQ wasn't totally artifact-free. The I channel lies along flesh tones, so edges of faces are not distorted in hue when the color along the edge consists only of I -since ther is no Q in the flesh tone to begin with. But sharp-edged objects of other colors, like yellow letters in movie titles, would develop reddish-orange edges. This could be somewhat objectionable unless you were viewing from a good distance. The comparable effect in an equiband set is a reduction in color saturation near the edge, which is less noticeable unless you have the original RGB picture to compare to.

The one thing that definitely improved with proper I/Q demodulation is a reduction in red smear and improvement of the detail in red textured objects. My opinion is that the wideband I was wasted on the 15GP22 - the picture was just too small - but on a bright, modern 27 inch tube, say, it could have been quite noticeable, if not for all the problems of doing it well.

OP/ED ends....

Wayne, great writeup of your personal experience evaluating the original wideband, low level chroma demodulators of the original CTC2 chassis versus the narrowband, high level demodulators of the CTC4 and later chassis. You suggested that the performance improvement of the CTC2 was probably wasted on the CT-100's 15GP22 small size. Well I had an opportunity of verifying the obvious superiority of the CTC2B over the CTC4 in 1964 when I had both TVs converted to the much larger, much brighter 21FBP22s. I described the comparison in my first 21CT55 thread of Feb 28,08:

"When I bought my 21CT55 for $50 in '64, I brought it into the house after I got it working and ran it along side my Dad's old CTC4 he left me. Both had 21FBP22s so it was a good comparison of narrow bw color R-Y B-Y vs. full bw color I Q. The extension of full color into fine detail on the CTC2B was startling! Color persisted in fireworks until extinction which I never saw before. The CTC4 fireworks turned into white long before extinction. The CTC2B carried full color way into the shadows, the CTC4 went gray to black. I kept the CTC4 in the house for the kids but brought the CTC2B back to the garage workshop for further study. Ease of working on the chassis and CRT "forced" me to destroy the cabinet and configure the remains into the vertical chassis configuration I am blessed with today. That’s alright with me. I respect the original CTV restores but that’s not my thing."

I'm looking forward to view the screenshots of all the restored tubed roundys out there displaying DVD test patterns, direct or thru a good modulator. Hopefully a few will be 21CT55s............Tom

As you may recall, I complained that the dynamic convergence controls didn't seem to have enough range. When I took a closer look at the neck hardware, I realized that you can't see the internal pole pieces in the rebuilt 21FBP22 tube. So, I took out the souvenir bad gun from the 21AXP22A rebuild attempt, and used it as a guide. The parts that are visible in the 21 FB are not quite identical, but I hoped it would be close enough. When I moved the convergence coils back to match the old gun, voila! The red and green now can be converged.

Blue horizontal is still a problem, but it now seems that there is a mechanical problem with the blue amplitude control. It's very hard to see this coil, since it's mounted on a second flange some distance behind the main control panel, but trying to align a flashlight and my eyeball, I can't see a brass screw like the other coils; and. I have not been able to find a slot by poking around with a screwdriver. Now I guess I'll have to pull the chassis to check it out. I can hope that the core will be laying inside the set, but it most likely is broken or missing.

I have been following the progress of my fathers ctc-5 that Wayne is restoring to life. It has been a long time since a picture was displayed on this set. I have memories of this television sitting in the norh east corner of our living room on Sacramento Blvd. in Chicago. I remember going up to the flat roof of our house with my Dad and tinkering with the in-line two dipole antenna aimed at downtown . My brother and I were not permitted to use this set . Only special weekend color shows were allowed. I did sneek turing it on when a color Cubs game was on what a treat. When my mother got close to the crt with the upright Hoover, the set had to have RCA service come out to use the magnetic ring to get the blue and green patches out. My heart felt congratulations to Wayne and all that helped him with parts and advice. One more memory is having a living room of cousins watching the movie Buss Stop and the fantastic color . Everyone was spellbound. Thank you again,I am in tears. John L.

John, you put that RCA in excellent hands! I'm really glad you didn't let it get destroyed like so many others. Great stories, too!

I hope the blue-lateral control's placement in your photo was rotated for illustration purposes only? If not, something is terribly wrong! Is that the one that came with the 21AXP22? I looked thru my junk but I couldn't find one like I have on my 21FBP22. It is directly over the blue gun's lateral pole pieces as illustrated and has a rotation adjustable magnet that provides precise control without any interaction with the red and green screen locations. I hope the photos are useful.....Tom

Tom, you seem to have a different type of magnet assembly. The one in my picture is supposed to be placed as shown with one end over the internal blue pole piece. When I first got the set, I thought maybe it was accidentally shifted, but no. It is shown this way in both the RCA and SAMS manuals for the CTC-5, and is working properly in this position. I don't think there would be any difference based on changing to a 21FBP22, but there would be a difference if I had the same type of lateral magnet that you do. Steve Dichter sent me a couple of scans from different publications also showing the type I have mounted the same way mine is.

It appears that the end of the cylindrical magnet in mine is broken off, or at least an adjustment knob is broken off. It's still functional, but loose, and that is apparently why it was taped in position.

Edit - thanks for the photos with dimensions - I will compare to what I did.

My wife dragged it home from a garage sale in 1996 for $35. I fixed the remote and got a picture with no ant. Since I had no interest in TVs at the time it just sat disconnected in my office collecting dust. I finally fired it up on a test DVE disc thru a modulator a couple of days ago and got a bright, fine detailed picture with accurate color and near perfect focus! Well that got me interested in learning more about it.

Its a 25in Zenith System 3 made in Springfield, Missouri in April 1986. The CRT is A63AAX02X with a backward cap R sticker which makes it Japanese, right? The screen is stripped like my Sony Trinatron and probably has inline guns. When I took the back off, the CRT has NO convergence assembly like the Sony, just three purity rings stacked together! The yoke has only the usual 4 wires, so no dynamic convergence in here.? The ultor is a single conductor, so no electrodynamic convergence like the Sony Trinatron. I thought the Trnitron was hard to understand but this Zenith thing is spooky!

The plug in assemblies are noted as follows:
Video output 9-467-01
Main module 9-518
SM pwr supply 9-520-02
Tuner 175-2277-01

So what do the Zenith Gurus make of this. Its got 10yrs of main TV use, then retired for 13yrs and still produces a picture as good as any of my analog TVs with the obvious exception of the Sony PVM1334 super-fine pitch pro monitor.

This is typical of a self-converging yoke/tube design. The basic convergence is done by the yoke design. Touch-up is by tilting the yoke and adjusting permanent magnets. The in-line guns and striped screen mean the purity is not affected by vertical perturbations, so this degree of freedom is available to apply to convergence.

Wayne, thanks for your reply to my misdirected thread message.......Tom

I borrowed the tool you really need for those brass-screw coils - GC8276, which is a hollow yellow plastic tube with a protruding screwdriver blade on one end (which you don't need) and a recessed screwdriver blade inside the other end (which does the trick). Anyway, I think I have conclusively determined that the core of the H blue amplitude coil is missing, so the chassis will have to come out again. Drat!

A little update - finally got around to measuring high voltage: 19.8 to 20 kv. Since this is within 2.5% of the value on the schematic (19.5 kv), I think it's OK. :thmbsp:

Not much progress - instead of pulling the chassis to inspect the blue convergence coil, I did some playing with video sweeps, and while in the process. the set developed a horizontal instability that I can't diagnose so far. At first I thought the AGC or tuner might be involved, but I can turn AGC down to a low-contrast picture and the problem remains the same.

Anyway, the horizontal phase became jittery, and occasionally drifts out of sync entirely. I've tried tapping on things and wiggling tubes and wires, and tuning off channel and back, but haven't found anything that causes it. Also tested tubes (although I don't have subsititutes for most), and all in the sync/AGC/horizontal check OK.

Not sensitive to line voltage either. It did seem to clear up by itself for about 30 seconds after warmup when the set had been off for 10 minutes, so I may have to chase some thermal problem.

These old sets do have "personality!"

Any suggestions gratefully received...

I would consider replacing all the silver mica caps in the horizontal sync/phase/oscillator circuitry if you have not done so. Try removing each input to the phase detector and see if the oscillator becomes stable again (even if it is not being synchronized). Another possibility is a carbon resistor that has begun to behave badly. I have seen resistors give some funny symptoms.

When I get the chassis out, I will make some resistance checks.

Assuming the problem is caps, though, do you recommend replacing silver micas with silver micas, or with ceramics?

Silver micas for silver micas. I am not smart enough to figure out which ones could accept a ceramic cap. And silver micas are still readily available, and not expensive.

Not much progress - instead of pulling the chassis to inspect the blue convergence coil, I did some playing with video sweeps, and while in the process. the set developed a horizontal instability that I can't diagnose so far. At first I thought the AGC or tuner might be involved, but I can turn AGC down to a low-contrast picture and the problem remains the same.

Anyway, the horizontal phase became jittery, and occasionally drifts out of sync entirely. I've tried tapping on things and wiggling tubes and wires, and tuning off channel and back, but haven't found anything that causes it. Also tested tubes (although I don't have subsititutes for most), and all in the sync/AGC/horizontal check OK.

Not sensitive to line voltage either. It did seem to clear up by itself for about 30 seconds after warmup when the set had been off for 10 minutes, so I may have to chase some thermal problem.

These old sets do have "personality!"

Any suggestions gratefully received...


One other thing you should check is the grounds on the board. I have seen grounds cause all sorts of problems and the best way to cure them is hard wire the grounds to the metal chassis. Heat from the tubes and such will cause the boards to warp. Man,You have done a lot of work on that set and it looks nice.
Ed

Assuming the problem is caps, though, do you recommend replacing silver micas with silver micas, or with ceramics?

Don't use ceramics, they drift too much with temperature. Else you'll be forever twiddling with the horiz hold knob.

Thanks - I wasn't sure if NP0 ceramics might be preferred. I'll just stick with micas.

I suspect in some applications NP0 ceramics might be OK, though the tolerances on ceramics tends to be not as tight as the silver micas. But the advice of wa2ise is best. Safer to replace a give type cap with the same type.

Well, I'm accumulating a to-do list:
Blue horizontal amplitude coil
Blue static pot
Silver mica caps

I took a look at the schematic for the blue static convergence pot - bah! It's a special - 100 ohms, with a tap at 25 ohms. I doubt I will find one. However, the red, green and blue DC pots are identical electrically and are tied in parallel - tops, bottoms, and taps -so. if the red or green happen to be sitting at a different rotation compared to the blue, I could just interchage the wiper connections and avoid the bad spot.

Waiting for some mica caps to show up in the mail - any day now, hopefully tomorrow, so I can start work on the weekend.

To do:
Blue horizontal amplitude coil
Blue static pot
Silver mica caps
Find out why the luma freq response is only 2 MHz - the manual shows 3 Mhz
See if focus control can be centered better

I think this hobby is proof of the law of conservation of difficulty :D

Here's the latest -
last weekend I pulled the chassis, but had nto time to work on it, I had it flat on the table, and tonight I turned it up to look at the bottom, and the missing core dropped out. It was somewhere all the way at the back of the chassis - I don't knoe how it could have arrived there.

Now the bad news - in trying to re-insert the core, I cracked it. The brass screw does have a slot internal to the core, so it could be driven from the rear. Apparently the threads were galled (maybe deliberately so that no one should screw it all the way in and lose it like happened here). Anyway, I'm guessing I got the screwdriver cocked and applied pressure to the ferrite, cracking it.

The pictures show
(048s) the original coil in place
(052s) Top - possible replacement? (would have to remove a lot of windings, I think)
middle - core from "possible replacement"
bottom - broken core from original

dagnab it! :sigh:

Wayne, if you will measure the length of the broken ferrite core, and the length of the protruding threaded rod, I may be able to help with a replacement core. I am assuming the material is the same as that used in horizontal width or linearity coils. I assume your coil is OK, other than the broken core? Send me an email.

Thanks jonh - email coming

And now the (slowly) continiung saga...

Thanks to John Folsom, I got a replacement coil (images attached). It doesn't look like the original due to having 2 windings for multiple uses. I decided to try using just the core and the mount with the old coil, which seems to have worked well (won't know for sure until I fire it up). First tried the core to make sure it would fit without binding. Then tried screwing the brass screw intot he old mount, but apparently the mount was damaged, so gave up and replaced the mount. As you can see, the replacement came with two different sized mounts. The smaller one fit the old coil.

I have had the mica caps for about 2 weeks, but no time to work on the set - will fix that tonight or in the coming week.

News on the DC convergence pots is not so good. The blue pot wiper is definitely got a big bad (open) spot. Also found out from looking at the wiring and verifying on the RCA schematic that it's not identical to green or red physically because it rotates the opposite way and the tap is towards the other end. Anyway, Cailube doesn't fix it, and in the process of checking all three I discovered the red DC pot has a bad spot too. Have to think some more aobut how to fix these

Wayne:

Here's something to try for the blue convergence pot. Get a 200 ohm pot (Nebraska Surplus sales has several types) and put a 50 or so ohm resistor in series with a 150 ohm resistor and connect the ends to the outside terminals on the 200 ohm pot. This will make the overall resistance 100 ohms with a centertap at the junction of the two resistors. You will have to mount it somewhere else on the chassis or perhaps you could find a pot that can replace 100 ohm section in the dual section in the set now.

Steve

Well, I've been working on the DC convergence some more. If you look at picture ...002 attached, you see the DC convergence in the earlier chassis, and in pic ...003 you see the later chassis I have where the blue lateral changed to a permanent magnet. In this case a 82 hm resistor has been added so that the circuit draws the same current. The reason is, this whole mess is the cathode resistance for the horizontal sweep output tube! The DC in the convergence coils is developed between the tap on the potentiometer and the wiper on the potentiomenter. Since I can't get tapped potentiomenters, I am going to use the circuit in pic ...004. The fixed resistors supply the tap point, and the three 250 ohm pots supply the variable voltage. Hopefully, the extra resistance won't reduce the dynamic current too much. We shall see.

The blue DC pot was open end-to-end as well as having a big bad area where the wiper is open. The resistance to ground at the cathode of the HO is supposed to be about 25 ohms, and measured 70 ohms. Maybe this is why the set has been sensitive to particular choice of HO tube.

I put the 250 ohm pots in a little open-backed plastic box, which I planned to mount just behind the cabinet back, so the shafts will protrude through the holes in the back. One oops - I forgot that the back insets into the cabinet frame, so there is no depth left to mount the circuit box. Will have to add a bracket of some kind.

Well, I got it put back together, and... it doesn't work right. Apparently too much resistance in series with the vertical convergence coils, which I was afraid of. Just for yucks, I tried reversing the convergence yoke (so the red coil is over the green gun and vice-versa). That resulted in better DC convergence (but still not enough range), plus the best DC setting put so much resistance in series that the vertical dynamic controsl have little effect.

At least the horizontal output seems to be OK, and no smoke was observed.

Well, back to the drawing board.

Oh yeah - still have to try the blue horizontal adjustment range with the new core.

Wayne,

I don't know if this will be of any help, but it is worth a try. I had a ctc5 Special with a bad crt, I sold it to a fellow by the name of Ed Milbourn in Indiana. He wanted my set as a source of parts to restore another CTC5 that he was working on. Ed may have the parts you are looking for and may be willing to sell you what you need.

Tell him Bob Galanter in Milwaukee who sold him the ctc5 gave you the referal. Ed is a real nice guy and I would think if he has what you need he would be happy to sell you the parts.

BTW, Ed is looking for a 21axp22 that he can use in the restoration he is working on. I think he may even be open to one that is weak but undervacuum and can be rebuilt. If anyone can help Ed on the crt issue, please contact him.

Ed's email address is:

[email protected]

Bob

Bob, thanks for the hint. I'll send an email and see what happens.

I won't be able to work on the set for the next 5 or 6 weeks, as I will be traveling for business (and some for pleasure). Fortunately, one of the pleasurable parts will be the Early TV convention in Hilliard, and I'm thinking I might be able to find some help there. If not, the one thing that will definitely work is to put in two pots in place of each existing one, with a movable connection to select either the top wiper or the bottom wiper.

I showed the problem to someone at work, and they said "I wonder how the engineers at RCA designed the circuit in the first place, assuming they didn't have the unusual tapped pots when they started?" Something to think about, but other than clip leads and decade boxes, we haven't thought of any way to breadboard it.

I made contact with Ed, and he can supply the pots. He's also going to Hilliard in May, so I look forward to meeting there. Thanks, Ed, and Thanks, Bob for the contact.

Time for an update!

Ed Milbourne indeed did supply the unobtainable pots. Progress then got interrupted by travel in May. The bad news is that two of three existing pots were bad, and of the three removed from a junker by Ed, tow were bad. Guess this was a weak point in this chassis.

Attached scan and previous attachments show original DC convergence circuit with 100 ohm pots tapped at 25 ohms (CTC-5 DC conv003), and an attempt I made to get results using a separate fixed resistor divider for the tap point CTC-5 DC conv004). this didn't work becuase the dynamic convergence drives are in series with this resistance and wete thrown out of whack. CTC-5 DC conv005 shows the final thing I cam up with, replacing each tapped pot with two pots and a SPDT switch to select either and upper or lower wiper position.

.

Here's what the result looks like currently.
DC convergence can be made for any combination of dynamic convergence controls. Unfortunately, it does not seem possible to get enough range on the vertical dynamic controls. Also, the horizontal dynamic controls still don't seem to do much, if anything. Now I will have to go snooping for waveforms to see what';s happening, I think. It's still hard to tell if the convergence coils are at the right position. The yoke prevents them from moving forward any further when it's in the right place for purity

A friend took apart one of the bad pots, and here's what he found. The carbon element (deposited on paper/phenolic?) is burned and has lifted from the (phenolic?) substrate.

I wonder if that couldn't be glued back down and then bridged with some sort of conductive paint - rear window defogger coating, maybe?

The guy who took the pics tried something called "liquid wire", but foudn it's not so conductive - the burned segment should be 25 ohms, but he ended up with a few hundred ohms. The total is supposed to be 100 ohms. I suspect this low resistance and the high currents involved (compared to a video or audio signal) are pushing the carbon pot technology beyond its limits. I suspect high contact resistance could develop and then there would be local heating. Don't know why they didn't use wirewound pots for this function. The circuit I came up with using two pots has a wirewound 25 ohm in it, mainly because that's what I could find. There is no problem with coarseness of adjustment for this application.

I'm also looking for info on how to fabricate the correct mounting brackets for retrofitting a glass 21FBP22 (actually a delaminated 21FJP22) in place of an (aired) metal 21AXP22 to restore a Sylvania model 31C304M, hopefully without hacking up the shroud used with the 21AXP22, thus making the retrofit reversible in case a fix for leaker 21AXP22's becomes available.

Another question I hope someone here can help answer is whether anyone has data on feasibility of making an adaptor for use in bench testing an early 21" color chassis with a test rig.

I have the GTE/Sylvania CK-3000 test rig and know someone with a TeleMatic rig. For both units, the earliest color chassis supported directly by its adaptor complement was the RCA CTC-7. If a correct set of Yoke Program, Convergence Ballast, and Yoke Cable characteristics could be determined, then the use of test rigs would help simplify these early sets' restorations greatly. It would seem that the correct yoke wiring harness could be as easy to create as making an adaptor to mate the leads of the existing "roundie" yoke harness to the correct plug for the older chassis. That would leave only the correct Yoke Program and Convergence Ballast values and pinouts to be determined, since the CRT cable should be directly compatible with all 21" color tube applications.

Wayne, Surplus Sales of Nebraska
http://www.surplussales.com/Potentiometers/PBM-Shafted/PBM-Shafted-1.html
has 100 ohm 2 W wirewould pots. I think you could disassemble the pot, modify it to add a fixed 25 ohm tap, and reassemble. A little tricky, but it could be done.

John, thanks for the link. Right now, filing for future reference, Need to think how I would mount them in place of the existing ones that are dual-consentric.

Before going the Surplus Sales of Nebraska route, I'd give Play Things of the Past a try - they are a LOT less expensive, and he has tons of pots.

Play Things of the Past Pots (http://www.oldradioparts.com/2a22fil.txt)

He had the pot for an old Philco TV I helped restore. Just be aware that the Clarostat RTV series are huge 2-1/2" round pots. Dual ganged pots they are, but huge.

Anyone have an old Clarostat catalog with their A47 series stuff? Seems they would have made replacements for all the RCA stuff - they covered (gasp!) Muntz! And yes, they made dual element and tapped stuff too.

IRC and CTS also made kits that had various elements, shafts and housings so that custom pots could be "built" - perhaps someone might have one of their old catalogs or an Allied Radio catalog with their potentiometer line listed in it.

What are the orginal RCA part numbers for the pots? Drawing numbers? Maybe RCA superceded them with a new number -they loved doing that!

Cheers,

Thanks for the info and ideas. I had some eye surgery recently, and have to stay away from lifting the chassis in and out while I heal. So, it's a time to make plans, but out of action for a while.

I have the GTE/Sylvania CK-3000 test rig and know someone with a TeleMatic rig. For both units, the earliest color chassis supported directly by its adaptor complement was the RCA CTC-7. If a correct set of Yoke Program, Convergence Ballast, and Yoke Cable characteristics could be determined, then the use of test rigs would help simplify these early sets' restorations greatly. It would seem that the correct yoke wiring harness could be as easy to create as making an adaptor to mate the leads of the existing "roundie" yoke harness to the correct plug for the older chassis. That would leave only the correct Yoke Program and Convergence Ballast values and pinouts to be determined, since the CRT cable should be directly compatible with all 21" color tube applications.
Maybe you could get ideas for the correct adapter needs by comparing schematics of the CTC-7 (and -9, -11 etc.) with the older RCAs to see what major differences there might be. With very early color sets, there may not be too many differences from one brand to another, except the connector types.

Would it be possible to pull the yokes and convergance assembly with the chassis and hang them out of the way for a test on the CK3000. Just connect the picture tube socket and the high voltage lead. I have done this on a newer set I didnt have the programmer or yoke adaptor for.

Bill R

If you left the deflection and convergence yokes from the TV connected and hanging loose, but plugged the test jig's CRT and high-voltage connectors in, all you would get on the test jig is a bright spot in the middle of its screen if the TV chassis was at least partly working. That would tell you the chassis had high voltage, but almost no other help.

If you left the deflection and convergence yokes from the TV connected and hanging loose, but plugged the test jig's CRT and high-voltage connectors in, all you would get on the test jig is a bright spot in the middle of its screen if the TV chassis was at least partly working. That would tell you the chassis had high voltage, but almost no other help.

It would also damage the CRT in your CK3000 by overheating and burning the phosphor in the center of the screen. Operating any CRT without deflection is a BAD idea. Even prolonged operation of a set which had full horizontal sweep but no vertical sweep would quickly burn a line across the face of the CRT, thus ruining the tube. Deflection is required not just to produce meaningful test results, but also to distribute the energy dissipation due to electron bombardment evenly over the entire screen surface to prevent damage to the phosphor from overheating.

A wirewound can pot create stray inductance in an AC circuit. This is probably why they used a carbon pot.

It would also damage the CRT in your CK3000 by overheating and burning the phosphor in the center of the screen. Operating any CRT without deflection is a BAD idea.
Yes, I should have pointed that out as well. I don't know what I was thinking. DO NOT just hook up your chassis that way.

The most important consideration (aside from the obvious ones such as compatibility with 70-degree color chassis of any kind in the first place) in using a test rig with a particular model of 70-degree color chassis similar to one which it supports directly is matching the impedances of the respective yoke windings in the rig to those of the set's own yoke within a reasonable tolerance. For both windings, +/-10% is preferred, while +/-15% is about the maximum tolerable degree of mismatch. Most 70-degree color yokes will typically have similar impedances, within +/-20%, as an educated guess. Uncontrollable vertical "rolling" seems to be the most frequently occurring symptom when operating test rigs with 70-degree color chassis when there is a moderate mismatch of convergence ballasts. Of course, a severe mismatch could easily damage the rig or the chassis, or both.

The importance of avoiding CRT "burn in" on the rig, but especially the prevention of damage to the picture tube in the set under test, cannot be overstated. Burn-in is damage which not even a CRT rebuild can correct. Just like a snapped neck, the only cure for a badly burned screen is a replacement tube. Both of my "daily use" 5AXP4 tubes for B/W bench testing, my "spare" 5AXP4 tube, and my 8XP4 and 8YP4 tubes all show signs of having been operated without deflection at least once before I acquired them. When using these tubes, I insert them into the yoke of the chassis under test or disconnect the set's own yoke and connect the extension cables of an appropriate B/W "substitution box" unit (basically, the B/W equivalents of the CK3000, using either a 5" round or 8" rectangular test CRT) to all of the appropriate connections on the chassis under test. The tubes in these units have pre-existing "dead spots" in the center of their screens from prior misuse, but are still capable of producing a picture adequate for troubleshooting purposes. Until I can locate undamaged examples of them (probably would have to be NOS, since ALL "used" tubes seem to have been MISused at least once), my existing tubes will just have to suffice.

When performing grayscale setup of a color chassis, during which the Service switch will disable vertical sweep, it is very important to preset all three G2/Screen controls fully CCW and set CRT Bias and Brightness to completely extinguish the raster before placing the switch in the Service position. Failure to do this could permanently damage the set's own CRT in a matter of mere seconds. The MAXIMUM brightness of the Service line should be just barely visible in a dimly-lit room. Grayscale setup procedures outlined in textbooks on color TV servicing and/or service literature vary somewhat for different textbook publishers and/or set models. Some will specify that the Service line should be barely-visible, while others will state that the G2/Screen controls should first be set to the point where the line just appears and then backed off to the point at which the line is just extinguished.

For bw I use a remote mounted test crt with its own yoke. The leads have self-penatrating alligator clips. One day I had it hooked up and the clips weren't in far enough. When it powered up I was greeted with a small dot in the center that actually glowed orange. So, now I have a black mark in the middle. Not an issue at all for me, but a warning not to do things like that again!

John, I have a NOS test crt upstairs that a friend asked me to sell. If interested let me know.

It would also damage the CRT in your CK3000 by overheating and burning the phosphor in the center of the screen. Operating any CRT without deflection is a BAD idea. Even prolonged operation of a set which had full horizontal sweep but no vertical sweep would quickly burn a line across the face of the CRT, thus ruining the tube. Deflection is required not just to produce meaningful test results, but also to distribute the energy dissipation due to electron bombardment evenly over the entire screen surface to prevent damage to the phosphor from overheating.

It must have been a bad day for posting. I know better. In retrospect I know you have to connect the deflection cable. Duh. Took a week of vacation and back now. Didn't realize how bad I needed that vacation.

Bill R

Well, I finally got back in the old_tv business this weekend.

I checked out the convergence circuits by putting a current probe on the covergence coil wires, and I see all three are getting H convergence parabolas. However, I just can't get convergence, (R-G vertically and B horizontally). I tried playing with the positioning, since I can't see the pole pieces (covered by dag). I'm guessing now that I can't get the coils forward enough - the greatest action occurs when it is right up against the yoke, which has to be where it is for purity. (The yoke is almost all the way forward too, as you would expect after subbing the bell-shaped 21FB for the cone-shaped 21AX.)

Not sure what to try next - maybe if I forget purity and see how far forward the yoke will go, I can try moving the convergence coils further forward just to see if convergence improves.

By the way, the donor visited a few weeks ago, and was happy to finally see pictures on the set he remembers watching at home - so the work has some purpose so far, but I sure would like to get it right.

Another long hiatus, then finally got back to the set today. Since I can't see where the pole pieces are in this rebuilt tube, I was thinking maybe the convergence coils need to be more forward. Turns out the opposite is true. After a lot of back and forth and turning the assembly to see what position has the strongest coupling, I got the red and green convergence nearly perfect. However, the blue horizontal is still not doing anything useful. Don't understand why not, but at least there now seems to be a definite pointer that it's only the blue that's bad.

Wayne,

Perhaps a silly question, but have you adjusted the blue lateral magnet on the tube neck? It will move the blue dots horizontally.

-Steve D.

Wayne,

Perhaps a silly question, but have you adjusted the blue lateral magnet on the tube neck? It will move the blue dots horizontally.

-Steve D.

The blue lateral works fine. it's just the blue H amplitude (dynamic that causes the left and right blue to be deflected up or down) that is bad. The blue is OK in the center and the middle top and bottom, but the blue lines droop on the left and right.

.. the blue horizontal is still not doing anything useful. Don't understand why not, but at least there now seems to be a definite pointer that it's only the blue that's bad.
If the adjustment is having no effect at all, there may be a broken wire going to the blue conv.coil. It's hard to spot unless you're looking specifically for it. Those connections can get a lot of fatigue over time from movement of the conv.yoke assembly. Ask Phil Nelson! (: Bill(oc)

Edit: I just stumbled onto your remarkable saga for the first time. In reading it through, it looks like you've already investigated the above.

If the adjustment is having no effect at all, there may be a broken wire going to the blue conv.coil. It's hard to spot unless you're looking specifically for it. Those connections can get a lot of fatigue over time from movement of the conv.yoke assembly. Ask Phil Nelson! (: Bill(oc)

Edit: I just stumbled onto your remarkable saga for the first time. In reading it through, it looks like you've already investigated the above.

Well, I measured a waveform with the current probe, but maybe there is still a problem, like a short instead of an open. - More investigation needed - and I do appreciate the comments.

did some more investigation --

Measured the R,G, and B horiz convergence coils, zeroing out the lead resistance. Sams says 3 ohms. I measure 2.9 for R&G, and 2.1 for B - it appears the blue horizontal coil may be shorted.

I also tried rotating the convergence yoke 120 degrees to see if I could get some blue horizontal action from the green coil, but that messed up the convergence so much it's hard to tell. (I was willing to readjust the DC, but I didn't want to mess up the dynamic for the R&G, which are just about perfect now.)

While I contemplate what to try next, here's a little "White Christmas" on the set.

http://farm3.static.flickr.com/2767/4201736307_bf87610ff7.jpg

I probably should get the 4x3 version to view on the roundie.
Copyguard is a problem too - had to put it on pause and wait for the retrace bars to fade periodically to take this shot.

Nice pic.

put it on pause and wait for the retrace bars to fade periodically to take this shot.
I use one of these to remove copy-protection frick-frack while watching DVDs and tapes.

http://checkhere22.com/stabilizer/

Phil

Wayne....Very good cross-hatch conversion except for the blue horizontal sagging uniformly at both sides like there was no horizontal correction at all? If you disconnect the horz coil leads you should move the entire blue line up and down by applying a relative low voltage DC. It should act just like the static magnet rotation. If no movement, bad coil. I checked the CTC5 schematic and it shows independent horz and vert coils on a common form. My CTC2B is the same way, but the CTC4 has only a single coil fed with a complex H/V waveform. Too bad, I still have my CTC4 convergence assembly I'd send but it wouldn't work for you.

The Bing Crosby Christmas picture has great color, reds are sensational! That 21FB or 21FJ really pumps color, are you sure you still want to run a 21AX if you ever get a good one, and always wonder if and when it goes to air? I'd stay with what you've got.........Tom

Nice pic.


I use one of these to remove copy-protection frick-frack while watching DVDs and tapes.

http://checkhere22.com/stabilizer/

Phil

Thanks, I'll check it out.

Wayne....Very good cross-hatch conversion except for the blue horizontal sagging uniformly at both sides like there was no horizontal correction at all? If you disconnect the horz coil leads you should move the entire blue line up and down by applying a relative low voltage DC. It should act just like the static magnet rotation. If no movement, bad coil. I checked the CTC5 schematic and it shows independent horz and vert coils on a common form. My CTC2B is the same way, but the CTC4 has only a single coil fed with a complex H/V waveform. Too bad, I still have my CTC4 convergence assembly I'd send but it wouldn't work for you.

The Bing Crosby Christmas picture has great color, reds are sensational! That 21FB or 21FJ really pumps color, are you sure you still want to run a 21AX if you ever get a good one, and always wonder if and when it goes to air? I'd stay with what you've got.........Tom

You understand the coil situation perfectly. I can try the DC current and see what happens - I'm betting the blue H coil is dead. As you may know, the static convergence in this chassis is done via a DC current in the vertical dynamic coils, supplied by means of those unique tapped 100 ohm pots.

Regarding the 21FJ, yeah, the reds are OK, but the greens and cyans will never be the same as the 21AX. Besides, the R-Y gain really should be boosted for the 21FJ, which will make the reds even brighter, but most important, increase the hue variation in the red-yellow-green area. (The sulfide green is yellowish, therefore it's the same as mixing some red with the green, and therefore you want to increase the R-Y gain so red gets turned off more on greenish hues.)

I mentioned the copyguard problem to someone at work, and he said he had a home-made circuit to fix it. He brought it in today, and here is the result. I had to change the timing by adding additional capacitance - maybe his design was for VHS, and the DVD has more pulses?

Here's the result, certified by the Lollipop Guild:
http://farm3.static.flickr.com/2721/4205229198_a89a0cb0fa_b.jpg

:headscrat Well, I tried the DC power supply, and the blue coil works - seems to have the same sensitivity as the red or green - so it's back to head scratching.
Quitting for tonight, but tomorrow I'll try measuring with the scope again.

:headscrat Well, I tried the DC power supply, and the blue coil works - seems to have the same sensitivity as the red or green - so it's back to head scratching.
Quitting for tonight, but tomorrow I'll try measuring with the scope again.

If you have a shorted turn in the blue coil as you suspect, it will not affect the DC test if it's only one turn or so that's shorted. But, at higher frequencies, i.e. the dynamic convergence, it will null the field. If you have a ring tester I would try that.

John

Don't have a ring tester. Tried unclipping the blue and red coils and interchanging their posititon on the convergence yoke, but the result is very confusing when the red and green no longer converge.

I noticed that the blue H tilt circuit uses a different capacitor value than R and G (.47 vs .39) - now I'm thinking that the convergence coil inductance is part of the pulse shaping, and if the blue is 1/3 shorted, it may be impossible to get the right waveform. I tried running the blue H tilt end-to-end, and I can make the B H convergence worse on the right side, but there is no travel to make it worse on the left side. So, this control does not seem to be centered, which again could be due to the convergence coil itself being bad.

By the way, the blue core looks cracked, but I'm not sure that is making a difference, since the mounting clip holds it tightly together.

Nice pic.


I use one of these to remove copy-protection frick-frack while watching DVDs and tapes.

http://checkhere22.com/stabilizer/

Phil

got mine today - works as claimed

got mine today - works as claimed

on closer inspection, it seems to be reducing the burst and/or chroma level, and the CTC-5 doesn't exactly like it - will have to make some sweep measurements.

Through some serial kindness (Ed Milbourn had given a convergence assembly to Bob Galanter, who only needed the connector, and gave the rest to me), I've been able to fix the blue horz convergence.

Before doing anything else, I measured the convergence coil resistances. Turns out the blue coil is 2.4 ohms, just like mine, and the R and G are 3.0 ohms, just like mine. So, it seemed SAMS was wrong in listing all three as 3 ohms - probably as close as they could get at the time.

I went back to the set and:
1) pulled the convergence plug - blue H lines still drooping - so I guessed it's not due to >too much< blue H current. Then I put the current probe on the R, G, and B in turn and noted that all three had about the same H parabola current.
2) with the current probe on blue, started turning H tilt and H amp, noting as before that the tilt had a noticeable effect, but the amp had little or none. The H amp adjustment is a coil, and if you look way back in the thread you will find that I had broken the core and used a replacement from John Folsom. Well, the replacement has a much longer screw thread, so I decided I would just turn it as far as I could CCW and see what happened. Well, after a number of turns, the core started to really move out of the coil, and the current went way up - eventually I could get the blue lines to curve >up< on the ends. Readjusting the tilt (which was now wrong) and amplitude iteratively got the results you see. R and G current is about 0.5 A p-p, but blue needs to be about 1.1 A p-p. I was just too timid on adjusting that core.


All 0.2 A per div:

red
http://farm3.static.flickr.com/2764/4234229223_42cbb3a7b5.jpg

green
http://farm3.static.flickr.com/2657/4235003374_25f05162c1.jpg

blue
http://farm5.static.flickr.com/4030/4235003466_8e005c8342.jpg

result
http://farm3.static.flickr.com/2626/4234229157_f3b5299406_o.jpg

http://farm3.static.flickr.com/2626/4234229157_f3b5299406_o.jpg[/url]

Beautiful!

on closer inspection, it seems to be reducing the burst and/or chroma level, and the CTC-5 doesn't exactly like it - will have to make some sweep measurements. I tested one using Cliff's sweep DVD. My feeling is the unit is useless even for semi-serious work. The chroma tapered off a little, but the luma looked like a ski slope.

Pete

Next big effort is a complete tuner/IF/chroma alignment; figuring out if more video drive can be obtained (video output tube? AGC?), finding out why the luminance frequency response seems too low, trying to reduce the chroma ringing, etc.

See some screen shots:
http://www.flickr.com/photos/42002845@N02/sets/72157623116659120/

A very good start to the new year, great work Wayne!

Way to go, Wayne! Boy, I wish MY screen shots looked as good as yours! Good luck with the alignment and final tweaking.

Wayne….I blew-up your crosshatch and I’ve never seen a more proper convergence on any roundy screen shot! I haven’t seen a live roundy screen in the last 30 years except my 21CT55, but yours is better. Your color is great but lacks fine detail. I hope you can find the luminance BW problem in the RF and / or video portions of your CT5. Have you been using test DVDs like DVE that have video freq sweeps and resolution wedges? I suggest you install an external composite video injection circuit at the grid of the first video amp and get the best picture possible from your DVD player before you dive into the Tuner/IF portion. This worked for me on the CTC2B chassis, since the RF and video systems don’t cooperate in determining the overall video BW of the receiver. I’ve got a schematic for an ext input circuit if you’re interested……………Tom

The convergence wanders a bit over time, and I think some red misconvergence is visible in some of the Rose Parade shots - tweaking it could be a lifetime hobby.

I found that fine adjustments of the position of the convergence yoke help, as well as the controls themselves. The R,G, and B should be independent, but they may not be perfectly so. I moved the convergence yoke back and forth until I got the maximum effect, and also tried rotating it slightly left and right for the best overall result. I think the rotation helped get it aligned for minimum interaction between R, G, and B. Mis-rotating the blue lateral from its nominal position can also affect R and G.

By the way, my set has a blue lateral magnet like the CTC-7, not either the CTC-5 DC coil or permanent magnet. It looks oddly crooked with respect to the gun structure when mounted correctly.

Here a diagram and some photos of the neck components:

http://farm3.static.flickr.com/2685/4241826481_daa0cf00ba.jpg
http://farm5.static.flickr.com/4002/4241826547_296140f714.jpg
http://farm3.static.flickr.com/2721/4242599080_8fa8d50159.jpg
http://farm5.static.flickr.com/4023/4242599122_2d464e7f29.jpg

Well, I went poking about the video board to see if there was anything obviously wrong that might reduce the luminance frequency response. All the peaking coils measure the correct resistance. Shorting them or bypassing with a large cap generally makes things worse. The coil in series with the delay line is critical to matching the delay line impedance and preventing reflections that show up as a ghost image. Bypassing or shorting that one increases the high frequency response somewhat, but produces the reflections. Comparing to the CTC-7: the CTC-7 has some different RC values plus an added coil in the cathode circuit of the first video amp. I suspect this is added video peaking.

So, I think the video amp is performing pretty much as designed, which is to say, it could be much better if there was a way to flatten the response to 2.5 MHz or more.

By the way, the spare video output tubes I bought did not make a difference.

This morning, one of them decided to fail, although it had tested good - picture started getting brighter and brighter and control had less and less effect.

Only thing left to try is a full alignment, though I'm guessing it's not affecting the luminance response, since there seems to be plenty of chroma.

Have scrounged enough parts to replace the broken blue lateral magnet, and also the missing spring clip to hold the convergence coils together around the neck. Of course, when replacing the latter, it was so tight that I managed to bump everything while fighting it, so had to go through the complete purity and convergence procedure again.

Still want to try checking tuner and IF alignment, but that will have to wait a while as April is going to be very busy for me.

Well, getting to the alignment did take "a while." Got a 2500 ohm 100W resitor to load the B+ with the sweeps disabled, read the procedure in SAMs and RCA about 10 times each, then realized I had to make some cables that were missing from the B&K sweep gen I bought on the bay.

Finally fired up everything today and started the sound alignment and video sound trap. Discovered the B&K will produce modulated IF marker frequencies, but not the modulated 4.5 MHz called for in the old procedures. No problem aligning the sound IF and detector, as there is an alternate procedure for doing it with a sweep. However, the video sound trap (actually a 4.5 MHz trap in the chroma take-off coil) only has a procedure for using 400 Hz modulated 4.5 MHz. So, I tried it with the sweep instead, and I hope I got it right, because it looked like the trap frequency was off quite a bit low. It was hard to see, though, because the chroma board is crawling with 3.58 MHz CW. [doh - just had a thought - before I tear down, I should see if I can kill the color oscillator temporarily - will have to try that] A wrong trap frequency could have something to do with the color ringing I have seen on color bars, but I really want to make sure I haven't screwed it up.

Next after the audio is to get everything connected for aligning the IF, which the B&K is fully capable of, even the procedure that uses CW at various frequencies and then checks the overall result with the sweep.

Today I repeated the 4.5 MHz trap adjustment with the color oscillator killed (0.01 microfarad from grid to ground). I was reading the wrong point when the 3.58 MHz was running and obscuring the waveform. The trap was not tuned as low as I thought and may not have been wrong at all. Definitely have it tuned to 4.5 MHz now.

BTW, the Sams said the trap is the top core and RCA said bottom. Sams is correct.

On to the IF...

This weekend I tried the If alignment and screwed it up. The first step of tuning the coupling coil between the 1st and second IF required quite a large adjustment, it seemed, and I did get to the correct response, but then the end-to-end sweep came out far too narrow. Will have to go back to the beginning and make sure the loading circuit is correct and connected to the correct point, leads are extra short, etc. etc.

Are we having fun yet?

Got back on this this weekend, but not as much as I wanted because I was called on to photograph the kids at the neighborhood block/Halloween party. Anyway, I couldn't get the 1st-2nd IF coil tuned right this time until I discovered that somewhere along the way I had switched to an un-terminated input cable - duh!

Now have to find out what I have been doing wrong in the over-all IF alignment.

One more thing: terminal "C" on the video board is the first video grid and should be grounded during alignment. Terminal "C" on the IF is filament supply and should not be grounded unless you like the smell of burning jumper wire insulation. :stupid:

Have fun with the alignment! I've read in a supplement that IF alignment should not be attempted as a fix, only as a last resort if all other fixes fail. Guess that shows to go ya how much the techs liked doing alignments, huh?

Have fun with the alignment! I've read in a supplement that IF alignment should not be attempted as a fix, only as a last resort if all other fixes fail. Guess that shows to go ya how much the techs liked doing alignments, huh?

Less than 1/8 turn of one of the cores in that dual-core coil can throw it out of spec (45% +10/-5% lower marker, 55% +10/-5% on the upper, IIRC). I can see that if you had no idea of how a double-tuned circuit should behave, you could be in trouble.

This reminds me of a job I had one summer at a UHF tuner manufacturer doing final alignment. Those who had experience (mostly women who had no electronics knowledge, but lots of experience aligning tuners) could do it about three times as fast as I could at first - because they knew what to expect for that design and could quickly see which way to go from an initial out-of-tune state. That was much worse than doing an IF alignment, since it involved getting stages to track across the whole band - and the tuner had peculiarities where it would develop a suckout at certain channels that could be reduced by very slight compromise of the over-all tuning. So, my first output tended to be very good on the good channels, but to fail inspection at the bad frequencies.

I've read in a supplement that IF alignment should not be attempted as a fix, only as a last resort if all other fixes fail.
It makes sense to eliminate simpler causes first. No need to rebuild an engine if it just has a dirty carburetor.

Phil

Well, it appeared that several coils needed adjustment, inlcuding some of the traps. Here is the result as it sits on the bench now.

On the left is the sound trap marker at 41.25 MHz (4.5 in video, not really visible because it's at the baseline), then about 10% up the left skirt is 41.67 (4.08 at video), then at 50% is 42.17 (3.58), then approaching the top is 42.67(3.08); and right above that on the skirt is 42.75, whihc is supposed to be up on the top of curve, but I can't get it there without ruining the overall response (think it's OK as is). At top right is 45.0 (per spec), then 45.75 (video carrier) at 50%, and hard to see at bottom right is 47.25 adjacent sound trap.

Well, I disconnected all the test gear and put the chassis back in the cabinet. Picture looks OK, but the problem with the sound volume getting low when the fine tuning is correct is now worse. OOPS - forgot to turn the page in the instructions and do the last step where one sound trap is deliberately detuned to get the sound carrier 22 dB below the video.

Well, since I understand what they are shooting for, I am going to try detuning it "by ear" while listening to the sound on the test pattern disc. Strange thing to me is that they say to detune it, but they don't say which way. I would think it should go towards the upper adjacent channel, that is, lower in frequency at IF, so it is moved away from the edge of the chroma. So, since I can't tell which way is which without the sweep, I will try both ways and see if there is any bad effect in the picture one way or the other.

This brings up a question: should the sound volume be so sensitive to the sound carrier amplitude? Can someone with a similar set try the fine tuning and let me know if it affects the sound volume strongly? If it doesn't, I should be looking for some sound trouble. BTW, I did check alignment of the sound section, so I know that's not it.

Can someone with a "Super" CTC-5 try the fine tuning to see if it affects the sound volume?

I 've read up on the schematic of the sound section and operation of the ratio detector. This chassis (the Super) has only one sound IF stage instead of two (in the Deluxe), so it may be gain-challenged. The ratio detector has some built-in AM rejection capability, but my understanding is that its output level due to the FM deviation is also proportional to the intercarrier amplitude if there is no limiting preceding the detector.

I've also ordered a couple of replacement sound IF tubes to see if that offers any improvement.

I completely detuned the sound trap, and now have reasonable audio (and do not have sound beat in the picture). Sound volume still varies some when adjusting fine tuning (runnning up and down the slope), so this set is far from being in limiting. Waiting to get the replacment tube(s) and see if that does anything.

Picture was blurrier than ever after the alignment (don't know if its supposed to be that way, or my efforts narrowed the IF too much). So, I tweaked the interstage to bring up the high freq video and chroma a bit. I'd definitely rate the "super" chassis as a stumble along the path of cost reduction of color sets.

I've decided I'm going to button this up for a while and get my living room back, at least over the holidays. Got the bezel and pencil box back on and the back installed. Will use it to view some DVDs of old Christmas shows, just because.

Now that I have my living room back, I turned the set around to face the room for normal use. Of course, I then had to touch up purity and convergence.

Have just been watching some Bob Hope holiday excerpts, some pix of which I posted to another thread under general topics, titled "Hope for the Holidays."

drat - forgot that I need to replace the channel indicator lamp, now can't see what kind of base it has, or find it in Sams, and don't have a tool that can get in to unscrew it.

Before I pull the tuner again, anybody know what bulb this is and where to find one? (suspect it's a common bayonet base bulb)

My Sams is for the CTC-5 Deluxe models. It lists under misc. a #44 bulb. Not sure if it's different for a Super chassis set. The other option may be a #47 bulb. Surprised it isn't listed in the misc. section.

-Steve D.

My Sams is for the CTC-5 Deluxe models. It lists under misc. a #44 bulb. Not sure if it's different for a Super chassis set. The other option may be a #47 bulb. Surprised it isn't listed in the misc. section.

-Steve D.

Thanks - the Sams for the Super chassis only lists the part number for the whole tuner, doesn't give the bulb number.

I find it interesting that on most of these restoration projects I keep reading “Recap Recap Recap”. The truth is if you have a vintage electrolytic that shows no leakage (infinite DC resistance) and ESRs’ (electronic series resistance or low AC resistance) good it will likely out last any attempt to stuff a bunch of small electrolytics in series in the old can to obtain the proper operating voltage. Yes they must be brought up SLOWLY to repolarize them. The critical ones are the deep cycling high voltage differential coupling caps. These are the ones that will eat your lunch and cost you flyback transformers.

One I have not seen mentioned is the high voltage rectifier. I have more than one crapy little $3.00 3A3 or 3AT2 eat a $60.00 flyback transformer. If the thing has any significant Edison effect on the glass replace it. Not a tube tester in the world will catch it and it will likely leak or short while your out of the room leaving you with a HV cage full of goo. Hope this helps. Good luck. Doogie

I find it interesting that on most of these restoration projects I keep reading “Recap Recap Recap”. The truth is if you have a vintage electrolytic that shows no leakage (infinite DC resistance) and ESRs’ (electronic series resistance or low AC resistance) good it will likely out last any attempt to stuff a bunch of small electrolytics in series in the old can to obtain the proper operating voltage. Yes they must be brought up SLOWLY to repolarize them. The critical ones are the deep cycling high voltage differential coupling caps. These are the ones that will eat your lunch and cost you flyback transformers.


But the vast majority of them will not show infinite resistance nor have decent ESR readings, we know this from experience. I will never trust a vintage set to a 60 year old cap, just as a matter of good practice. You may take your own chances as you see fit. As you already said, itmight cost you more than the price of a cap when it does god bad...


One I have not seen mentioned is the high voltage rectifier. I have more than one crapy little $3.00 3A3 or 3AT2 eat a $60.00 flyback transformer. If the thing has any significant Edison effect on the glass replace it. Not a tube tester in the world will catch it and it will likely leak or short while your out of the room leaving you with a HV cage full of goo. Hope this helps.

Not sure what this has to do with the alignments he's now currently engaged with, but would you care to explain what you mean by Edison Effect on the glass? If you mean the blue glow of electrons striking the glass, there's nothing wrong with that, but it's also not called the Edison Effect.

...if you have a vintage electrolytic that shows no leakage (infinite DC resistance)...
It would be open, period.
...and ESRs’ (electronic series resistance or low AC resistance) good it will likely out last any attempt to stuff a bunch of small electrolytics in series in the old can to obtain the proper operating voltage
ESR = effective (or equivalent) series resistance. http://www.maxim-ic.com/glossary/definitions.mvp/term/ESR/gpk/114
Frankly, never heard of stuffing a bunch of small ones in series in the old can.

"Edison effect" probably refers to darkening of the glass, which doesn't necessarily imply the tube is bad. But if it runs 'way hot to the touch after a few minutes, it would likely be on the verge of failing. That's the old school "life test" of a HV rect. :DBill(oc)

All tubes run hot to the touch, I use an infrared thermometer for getting actual temp readings but even that's not perfect since reflective surfaces throw it off some. Darkening of glass (though not mentioned here) doesn't mean anything either, it's just what happens after a lot of electron bombardment.

I just acquired a CTC-5 :banana:Very nice indeed :)

I hope ya still have it and are enjoying it :)

Reviving this thread because...
Someone sold me a working 21AXP22A! A GE-branded rebuild NOS in the box, measures in the middle green on all three guns on the RCA tester.

Here are the first pix after a day and a half of removing the "temporary" makeshift mount and 21FBP22 glass tube and reinstalling the metal tube support hardware. Plus about 40 minutes of roughing it in.

The SAMS bias set up procedure just doesn't seem to work right on this set. couldn't get any red at all until turning up the screen setting. Also, supposed to start with 130 volts red K-G, but can get 110 max. I will try the RCA procedure, which is somewhat different.

This set is still weak on luma drive, even with AGC cranked, so maybe I have to do something in the IF (replace tubes?). Replacing video outputs never cured it.

Images look much brighter in these shots than they really are.

http://farm4.staticflickr.com/3691/8844948159_8c050383e9_c.jpg (http://www.flickr.com/photos/42002845@N02/8844948159/)
003 (http://www.flickr.com/photos/42002845@N02/8844948159/) by old_tv_nut (http://www.flickr.com/people/42002845@N02/), on Flickr

http://farm8.staticflickr.com/7400/8845282066_a929185ffe_c.jpg (http://www.flickr.com/photos/42002845@N02/8845282066/)
First rough convergence with 21AXP22A (http://www.flickr.com/photos/42002845@N02/8845282066/) by old_tv_nut (http://www.flickr.com/people/42002845@N02/), on Flickr

I forgot to mention - yoke seems to want to be max forward for purity, would be nicer if it had some room to go beyond optimum point. Anyone who has worked with CTC-5, what is your experience?

(Of course, this may change, for all I know, after successive approximations to convergence etc.)

Hi All;
Old TV Nut, is successive approximations to convergence, Anything like when a group of Old Tv guys get together and talk of old times ??
THANK YOU Marty

Congratulations nut-man looks good....

maybe something off in cathode voltage divider network? I don't recall anything odd about the yoke setting to get purity.

I forgot to mention - yoke seems to want to be max forward for purity, would be nicer if it had some room to go beyond optimum point. Anyone who has worked with CTC-5, what is your experience?

(Of course, this may change, for all I know, after successive approximations to convergence etc.)

Have you played with the edge purity magnets? (The ones which are only adjustable after removing the screen frame. You are supposed to retract them before degaussing). I suppose the tube was well degaussed?

How good is the purity: do you reach the optimum purity pointwithf the yoke forward?

And also, what does the HV measure?

Have you played with the edge purity magnets? (The ones which are only adjustable after removing the screen frame. You are supposed to retract them before degaussing). I suppose the tube was well degaussed?

How good is the purity: do you reach the optimum purity pointwithf the yoke forward?

And also, what does the HV measure?

I'm getting decent purity; edge magnets are retracted. Thanks for mentioning degaussing - I actually forgot to do it! With the glass tube the set didn't seem to need it - purity was fine before and after degaussing.

Haven't measured the HV - it measured on spec before. (The spec for this chassis is rather low - I forget what exactly.) I do recall, however that the luma on the cathodes was low (compared to the chroma demod outputs on the grids) and has been since I got the set. Changing out the video output did not seem to help. I think a reasonable design should be able to generate luma drive at least half the p-p voltage of the color difference p-p on the grids. The chassis is capable of color difference p-p much greater than 2x luma p-p. Time to get out the scope and verify what I recall.
One problem is not having any service info showing waveforms with full color bars. The luma waveform with gated rainbow input is meaningless, so I have no idea if I'm getting the expected amplitude - but it seems low to me compared to the range that is available from the color difference.

By the way, I have solved a mystery - I noticed that a full red field (from a test signal, not from shorting the grids) looks washed out. If I am reading the schematic right, the color difference outputs are only 75% DC coupled to the grids. This, combined with about 75% DC coupling in the luma, causes a full red field to be washed out when color level is correct on color bars. I can't figure out why the designers reduced the DC coupling in the color difference. There have never been white balance problems in broadcasts that this might reduce. If they were worried about DC drifts in the demods, a 25% reduction would not be enough to fix it. Later sets used the RCA three-triode matrix amplifiers with "X-Y" demods, and the matrix amp circuit had built in DC restoration by drawing grid current when the negative blanking pulse was applied to the cathodes, so demod drift was not a problem. Just another way the CTC-5 super chassis is weird and inferior. If I convince myself I am right, I will try cutting out three .01 uF caps that I believe cause the 75% DC coupling in the color difference signals.

Another by-the-way: I couldn't follow the RCA gray scale set-up procedure, since it assumes there is no R background control and you set G and B backgrounds to match. This later chassis has background controls in all three colors. So, I tried modifying the procedure to a sort of hybrid of the RCA and SAMS. It looks better, but probably is not optimum. It probably won't be optimum until I can get more luma drive.

My Sams is for the CTC-5 Deluxe models. It lists under misc. a #44 bulb. Not sure if it's different for a Super chassis set. The other option may be a #47 bulb. Surprised it isn't listed in the misc. section.

-Steve D.

Finally replaced bulbs this time around - used #44, see no reason it should be different.

Congratulations nut-man looks good....


:D ....... just warms my heart , seein a squirrel complementing a nut :D

:thmbsp: And on a serious note , Congrats from me too on your new tube !

Any more good 21AXP22s where that came from? I could use one for my CTC4.

Finally replaced bulbs this time around - used #44, see no reason it should be different.
They spec'd a #47 lamp for a reason. The #44 lamp runs a bit hotter. The extra heat might melt or darken an irreplaceable tuning indicator. :sigh:

They spec'd a #47 lamp for a reason. The #44 lamp runs a bit hotter. The extra heat might melt or darken an irreplaceable tuning indicator. :sigh:

I did not find a spec for the bulb number, went by the post above that said #44 for the Deluxe chassis. Do you have a schematic that specs #47? I have those and could replace the #44s.

Any more good 21AXP22s where that came from? I could use one for my CTC4.

I don't think so. Got it from Pete Deksnis. Don't know how he got it, but don't think he has any more.

I did not find a spec for the bulb number, went by the post above that said #44 for the Deluxe chassis. Do you have a schematic that specs #47? I have those and could replace the #44s.

I would use #47's, to be on the safe side. If the indicator seems too dark, then go with the #44's.
I don't remember too well, as the last time I worked on a CTC5 was the mid to late 60's.

Been playing with the 21AX set up -

After the reminder about degaussing, I did it, and everything (purity, convergence) changed drastically. This did not happen with the glass tube, so I assume it's the metal cone itself that is the problem. I have been able to get the pure field purity back, but now white field purity is not so great. Probably have to play with the edge magnets.

Dynamic convergence on this tube is a problem - can't seem to get enough vertical red and green amplitude. The internal dag on the tube hides the pole pieces, so it's hard to tell where the proper convergence coil location is. It also seems like the blue lateral magnet interacts with red and green more than on the glass tube. I'm guessing there must be some differences between this gun and the ones Scotty used.

http://farm9.staticflickr.com/8278/8925326468_7d3071fdb3_z.jpg (http://www.flickr.com/photos/42002845@N02/8925326468/)
CAM00029 (http://www.flickr.com/photos/42002845@N02/8925326468/) by old_tv_nut (http://www.flickr.com/people/42002845@N02/), on Flickr

http://farm9.staticflickr.com/8417/8925325426_6cc1d9e8ae_z.jpg (http://www.flickr.com/photos/42002845@N02/8925325426/)
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Can someone who has a working CTC-5 Super chassis and a scope put in a signal with full black to white range and tell me what the peak-to-peak signals on the cathodes are? If possible, a measurement of the detector output would help too.

I've suspected for a long time that this set has low drive , but I can't find a good reference to what the level should be. SAM's is no help because it shows the signal for gated rainbow, which has little or no luminance signal.

Want you try a 6.3v white LED in your tuning dial,instead that's burns
Super cool and awhole lot brighter than the old style bulb..Jody

I have a spare cabinet for the CTC-5 in this thread, with a few of the parts including a back (will post more details tomorrow when I have a chance to look at it again). Legs were sawed shorter than original at some time before I got them.

Free to anyone who can pick it up or arrange/pay for shipping.

Otherwise, will have to curb it, as I am moving across country in a month.

I have a spare cabinet for the CTC-5 in this thread, with a few of the parts including a back (will post more details tomorrow when I have a chance to look at it again). Legs were sawed shorter than original at some time before I got them.

Free to anyone who can pick it up or arrange/pay for shipping.

Otherwise, will have to curb it, as I am moving across country in a month.

How much of it do you have? I might be interested.