Greetings,

I have been in on and off negotiations with a local collector (mainly vintage hi-fi) to buy his RCA CTC-7A roundie set. Today, I got a chance to look it over for the first time. It's in a cramped, dimly lit storage room with barely enough room to turn around. I took a few lousy photos with a flashlight and my cell phone which are posted below. It's unusual in that it's in a tabletop steel cabinet with a fake wood grain photo finish. The chassis is stamped CTC-7AA. I couldn't find the model number. The back is missing (he thinks he may have it somewhere) and the cabinet is filled with boxed tubes and what looked like the SAMS for the set. My visit was unplanned, so I didn't have my CRT tester with me so I don't know the status of the 21CYP22 which appears to be original.

Of course, now that I get to see it he's having second thoughts about selling it because "these are going to be worth a lot some day" :sigh:
Still, I think he may come to his senses and sell it to me. This would be my first color roundie, so I'm keeping my fingers crossed.

-Clark

how much was that camera that takes old 1940's Alfred Hitchcock murder mystery movie pictures? And where can I get one?

I have one of those metal cabinet CTC-7's but its in much worse shape than what you have there. My CRT one open filament (too bad as the others tested very well). hope you get it.

Offer him $200, see if he pops for it.

Doncha jes LOVE IT when sellers start gettin' "Cold Feet" ?!?

I believe the CTC-7AA is the late production Abington 21-CD-872-5,
Mahogany Grain Finish CTC7AA, 1958. Hope you can shed some real light on this set and get the owner to part with it. If he does, have him do a search for the back.

-Steve D.

Offer him $200, see if he pops for it.
Yah, cash talks. But I wouldn't phone him back right away. which only reinforces his idea that it's a treasure.

If you know it's been sitting there quite a while, wait at least a week, maybe two, and then show up with cash in hand and a big smile on your face.

Phil Nelson

It could also be the 21CD8712 Meredith. Source: RCA field service guide.
Phil, the last thing I would do is to go in with cash in hand and a big smile. I'd say here is my cash money offer, take it or leave it, and give him my phone number if he doesn't bite. If he has a wife flash the cash around her.
IsthmusTV, good luck.
Phil

Thanks for all the feedback. I've known this guy for years and the set has been there a very long time. I'll wait a few weeks and see what happens. He said that he might be interested in a trade. Of course, what he's mainly interested in is tube-type hi fi gear of which I have none. I think showing up with the cash may be a good strategy.

What I'd really like is to be able to test the CRT. If it's shot, I think I would walk away or make him a low ball offer.

Stay tuned!

-Clark

This set looks to be in nice condition. The painted woodgrain cabinets seem very durable as long as they're kept out of damp storage areas.

I do think the best way to get this TV, would be to show up with a tube hi-fi, or some juicy audio tubes. So keep your eyes open for those items, and then show up and offer to trade.

If I did not love the cabinet styling of my 65' philco roundy I'd offer it to you.

Hi Tom,

Thanks for the thought. Since we're so close distance wise, I'm sure that we'll exchange something along I 94 one of these days :thmbsp:

My guess is that I will eventually procure the CTC-7 from this guy.

-Clark

Well, I got my Christmas present early-- I got my first color roundie :banana: Yesterday, I got a call from the HI-FI dealer asking if I still wanted the set. He said he needed the room, and that I had to take it "as is" but for $100. I said, sure! Turns out that he just got another RCA roundie, also in a metal cabinet, but this one has the blond paint job. I saw it in the back of a freight elevator but I couldn't get close enough to ID it.

So, I was able to test the 21CYP22 before taking it and it woke right up with good emissions from all three guns:banana: It came with many NOS tubes and the RCA service manual. So far, he has not found the back. It is now home sitting on my dining room table. Things look pretty good overall, but I did find one troubling thing: A large quantity of grayish-white goo has oozed out of the power transformer (see photos). It's weird, I've never seen this color substance come out of a PTX before. It's still quite runny, more like grease than tar. Anyone seen this before? Seller thinks it was stored in hot conditions at some point. So, one of the first things to check is the health of the transformer.

I'll pull the chassis this weekend and post some more photos soon. I'm glad that I waited him out!

-Clark

Here's another shot of the goo accumulated at the bottom of the cabinet.

Great to see another one saved from destruction!:banana: I'm going to start on the second restoration of my blonde Anderson CTC-7B after the holidays. It's my first rounde that was bought after my stint in the Army in 1971. :D

Thats cool. I originally wanted a pre-1960 roundie as my first but living in this country it was never gonna happen unless I imported it.

Yes, a very small amount of gray stuff had come out of the power transformer on my CTC-7. Cleaned up pretty easily with something like mineral spirits.

I would definitely check out that transformer, and withhold judgement in the meantime. Mine seems fine; I replaced the electrolytics before applying power, of course.

Even if that transformer has fried, a CTC-7 with usable CRT is a good buy for $100. Congrats!

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

Thanks, Phil. I've read your account of your CTC-7 on your website and it was very informative as usual. I think I'll try your technique of cutting the EC cans right on the chassis. I'm keeping my fingers crossed about the transformer. I'm glad I'll have some time over the holidays to start working on it!

-Clark

I have a NOS transformer for a CTC-15 that spent the last 40+ years in a hot attic. It seems to have "sweated out" something similiar to that.

Great find...great Hallicrafters clock, too!

My 7 also has that gunk leaking out of the transformer, it works fine though.
I think it just creeps like a Glacier over 50 years time and starts to drip.

My 7 also has that gunk leaking out of the transformer, it works fine though.
I think it just creeps like a Glacier over 50 years time and starts to drip.

I'll say ditto to that. My 7 also had that gray gunk running down the chassis. Used some mineral spirits to clean if off. The set has been running fine after an electrolytic recap. Bob

You should see the stuff inside the PTX, I unbolted the top cover on mine to have a look... NASTY!

Thanks for all the replies. That's very reassuring to hear that the goo doesn't mean that the transformer is fried. I'll use mineral spirits to clean it up. My plan is to recap the power supply and then do a brief power up before replacing any more caps.

My cat, Gilda, definitely approves of the new acquisition. The jury's still out on the rest of the family!

-Clark

Could that goo be some type of coolant, similar to what PCBs were used for in power-line transformers? (I sure hope the RCA stuff is itself not a variant of PCBs.) If it is for cooling, the minor loss seen in the pictures (and described by others here) should not affect occasional short-term use by a collector, in my opinion.

Could that goo be some type of coolant, similar to what PCBs were used for in power-line transformers? (I sure hope the RCA stuff is itself not a variant of PCBs.)

I wondered about PCB content, too. I'll treat it with due caution while cleaning it up.

I had a very busy weekend but I did find time to pull the chassis and give it a quick once-over. It's very clean, with minimal signs of past repairs. The date stamped on the delay line is August 13, 1958:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020368.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020365.jpg

Here's one obvious hack repair:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020366.jpg

The fly has some melted wax but overall looks pretty good:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020369.jpg

I discovered that main fuse had blown, and someone used a piece of tinsel to jump it :nono: At least it would have offered some protection:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020373.jpg

There were over thirty boxed tubes included with the set, many NOS including 2 6DQ5s. Unfortunately, the one NOS 6BK4 had gone to air:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020371.jpg

Time to get a list of caps together. I hope to replace the electrolytics in the PS over the holidays and try a brief power up.

-Clark

Looks pretty good, overall.

I wonder if that tinfoil fuse had anything to do with the ocean of transformer goo?

I see that yours has a color crystal with flat metal envelope. My crystal is in a round glass envelope similar to a mini tube. Something I hadn't seen before, and I have both earlier and later RCA color sets that use the metal envelope. Perhaps mine is a replacement, or RCA was just using what was available at the moment. . . ?

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

http://antiqueradio.org/art/RCACTC-7Crystal.jpg

My CTC-9 uses a glass envelope color crystal.

Hi Phil,

I thought the same thing about the fuse. I REALLY hope that the power transformer is OK.

That's interesting about the crystal. I haven't seen the glass style used in a TV either. I would think that it might be superior to the metal type, at least in terms of its resistance to moisture.

-Clark

Looks like someone converted the power fuse to a "No-Blo" type. My CTC-9 had the same type of fuse. They are more difficult to find than the regular 3AG type so I changed the fuse holder. Now, I can still use the correct value fuse and it is much easier to find. I am not that much a purist to make this change.

That shunt regulator(?) appears to have gone to air.

Nice clean chassis! Just use a soft brush and some canned air on the PCB boards. Don't go overboard on those since they are easily cracked, especially those dark ones.

Hi Guys,

Yes, I think I'll just change the fuse holder to a more standard type instead of continuing to use the oddball ones (and certainly not the "no-blo" fuse it came with, LOL)!

I'll be careful when cleaning. Fortunately, this one doesn't have greasy kitchen grime or nicotine deposits.

In addition to the boxed tubes, it came with an original RCA service manual that is correct for the chassis complete with a fold out schematic. It's a little beat up, but usable. It contains notes from a TV repair shop with a previous owner's name dated 2002. So someone has been poking around in this thing fairly recently.

-Clark

BTW, I apologize for not congratulating you on finding and saving this piece of history. Glad that you have it in your hands. It is much cleaner than the CTC-9 that I have as mentioned above. Mine came with a booster on the picture tube. All three guns registered zero emission even when the filaments were cooked on 8 volts for about 30 minutes. Luckily I had a used CRT for it that was very good. I gutted the three electrolytic capacitors and stuffed them, brought it up on a variac with a Kill-A-Watt in series with it and got a raster. So, I know all of the major components are good. Please keep us posted...

Thanks, kvflyer. The is the one and only color roundie that I've been able to locate around here after months of looking. I'm going to take my time and try to do things right. I just placed a cap order with Mouser so that I'll have what I need to re-stuff the power supply electrolytics. I'm keeping my fingers crossed about the power transformer. I hope to have some time to work on this over the holidays.

Merry Christmas and Happy Hanukkah

-Clark

Congrats Isthmus!:banana:
I'm redoing a 7AH console with remote control,..mine had a BAD power tranny from a lighting strike from many years from the 1st owner leaving it plugged in during
a Thunderclap..got mine for $20 bucks 2 years ago at a estate sale locally nobody wanted it...its in great shape also all over except..having a blown tranny
got a new one from Moyers..last one they had on the self...found the thermo-switch is bad also..wonder how you would replace that?:scratch2::scratch2:

I did find some time this week to work on the chassis. It had been sitting on my workbench in a horizontal position for four or five days undisturbed. When I lifted the chassis, I discovered that a big blob of transformer goo had collected:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/XmasCTC7024.jpg
http://i1216.photobucket.com/albums/dd366/IsthmusTV/XmasCTC7025.jpg

Apparently, being horizontal got it flowing in new directions. Keep in mind, that I still haven't applied power and that the temperature in my workshop is about 60 degrees. This is a pretty large quantity of stuff. Is it possible that some sort of internal seal broke allowing this stuff to flow? Here's a shot after I scraped it off the carpet square with a penny for size reference:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/XmasCTC7026.jpg

On other fronts, I replaced the kluge repair with a proper resistor. I also found a charred 5600 Ohm resistor feeding the plate of the 12AZ7 color demodulator. It measured 144 Ohms! I wanted to find what had caused this overload. The 12AZ7 measured a bad HK short. In addition to the tube and resistors, I replaced a couple suspect caps in the vicinity:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/XmasCTC7027.jpg

I did use Phil's approach to the PS electrolytics. It all went pretty smoothly:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/XmasCTC7033.jpg

I also added a standard fuse holder, leaving the old one on place:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/XmasCTC7036.jpg

Two of the cans were definitely toast! I didn't even need heat to pull out the innards:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/XmasCTC7034.jpg

I ran out of time for now. I'll finished the third cap this weekend and attempt a first power up. BTW, all the windings on the power transformer look OK with an Ohm meter so I'm still reasonably optimistic that it will be OK.

-Clark

It's alive! I finished changing the PS electrolytics and did a first power up. At about 85 Volts, I heard the thermal relay close and the HV spooling up and saw the first raster :banana:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020404.jpg

I added a signal source and got this at about 100 Volts. The audio was excellent:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020405.jpg

At 117 Volts, it was drawing 2.25 Amps with no sparks, smoke or bad noises. The horizontal was close but wouldn't lock:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020407.jpg

The picture was nice and bright with good focus. I'm very relieved that the oozing power transformer is OK! It didn't get even warm to the touch after about 20 minutes. It even looked like the color locked for a while.

So a lot seems to be working well with this set. I'm going to recap the horizontal and vertical boards first and go from there. When I pulled the chassis, there were no signs of overheating anywhere, including where I replaced those resistors and caps. A nice start to the new year!

Happy New Year to all.

-Clark

Since you recapped it the horizontal frequency is probably off, tweak the slug on the board to get it back and you should have a watchable picture!

What I wrote wasn't very clear. At this point I've only recapped the electrolytic cans in the power supply. I'm preparing to recap the horizontal board now. I tried adjusting the frequency throughout its range and it won't lock. This is exactly what Phil Nelson experienced with his CTC-7. The horizontal wouldn't lock until he got rid of the maroon drops on the horizontal board.

I hope to have a watchable picture by tomorrow!

What I wrote wasn't very clear. At this point I've only recapped the electrolytic cans in the power supply. I'm preparing to recap the horizontal board now. I tried adjusting the frequency throughout its range and it won't lock. This is exactly what Phil Nelson experienced with his CTC-7. The horizontal wouldn't lock until he got rid of the maroon drops on the horizontal board.

I hope to have a watchable picture by tomorrow!

That absolutely makes sense. Unfortunately, it seems that almost every vintage capacitor is now leaky. And since the Horizontal will not lock, there must be a capacitor issue in the horiz section. Looking forward to the picture of the locked image on the CRT.

can you flop the horz lines? or will it just go one way like its out of range of adj?

What I wrote wasn't very clear. At this point I've only recapped the electrolytic cans in the power supply.


Oh. Well in that case, I'm surprised it works at all! :D

You'll surely have a very nice picture on it when you go through the paper caps in the rest of the chassis, don't be afraid to pull the metal cover off the color section underneath and have some fun there as well. There's at least 10 more hiding under that hood. Don't come hollerin' though when you wind up needing a matrix alignment, mine was so far out of whack from previous repairs gone wrong, it took me 2 weeks to figure out what the manual was asking me to do. After I figured it out though, it was a snap and now the set has a nice picture indeed.

Congrats!

Now you know that the unobtainium is all good. :thmbsp:

Congrats!

Now you know that the unobtainium is all good. :thmbsp:

Isn't that the truth! Congratulations! Glad to see it.

When I stuffed the filters of my CTC-9, replaced the CRT and got a raster, I was happy. But it will have to take its place in the queue!

I finished recapping the horizontal and vertical boards. I didn't have a .001 @ 2KV for the vertical board, so I left that one for now:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020413.jpg
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020414.jpg

When I fired it up this time, I was able to get the horizontal and vertical to lock easily, and a pleasant surprise-- color lock!
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020421.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020425.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020423.jpg

Not bad considering all the maroon drops that remain. On this chassis, there is no metal cover over the color section and everything seems pretty accessible.

To me it looks like the CRT is badly in need of degaussing (or is it purity)? And of course, I got rid of my degaussing coil years ago. Is there any kluge that I could improvise to degauss the CRT? I think I have a small tape head demagnetizer :D

I'm very pleased at how this is going so far!

-Clark

:DWOW! :banana:

Nice, yes a starndard purity setup will prob take care of the colors, and make them pop even better.

A tape head degausser will do more harm than good.
You could probably scrounge a degaussing coil from a newish CRT type junk set and use that with a variac to degauss the screen.
I got my degaussing coil from an active TV repair shop, and you may be able to do the same. Ebay may also have degaussing coils....

Just throwing some ideas out there...

Thanks for the tips and kudos. I think I may be able to borrow a degaussing coil from a friend next week, so I'm not going to try anything foolish in the mean time. Right now, I'm just happy knowing that all the vital organs (including the oozing power transformer) are good. I've never done purity and convergence before so this will be a real learning experience for me. I'm glad to know that all you experts are out there when I need advice :thmbsp:

The picture just keeps getting better. I adjusted the AGC which really woke up the contrast.

Now, I'm going to take a break and watch the Badgers in the Rose Bowl...

"Now, I'm going to take a break and watch the Badgers in the Rose Bowl... "
I can relate to that...just got a my CTC4 to display video an hour of two ago and had to watch it for an hour no color, poor focus, lousy purity, poor convergence and all. When a rare set comes back to life for the first time in decades ya just got stand there in awe.

Another 4 brought back!! congratulations! :D

Thanks! I got a thread going in this section of the forum if you want to see how it is comeing along.

Very nice. I wish I could just drop everything and work on my "stuff". But my CTC-9 is 737 miles away waiting for me to move to Florida. Can't wait...

I'm continuing to recap the whole chassis in stages. I also finally tested all the tubes and found a bunch that were weak, shorted or gassy and replaced them. I also carefully cleaned the tube sockets and the tuner with DeOxit applied with toothpicks and Q-Tips. The set now produces a very stable picture. (I still need to get my hands on a degaussing coil):
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020608.jpg

I decided to try a rough adjustment to the convergence, which was really bad. Things went pretty well until I got to the horizontal dynamic convergence:

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020604.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020602.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020603.jpg

None of the horizontal convergence controls seem to have any effect. Clearly, there is something amiss. I haven't begun to trouble shoot yet, as I thought I'd check in here first for advice. Any common failures to check out first? I wouldn't be surprised if the selenium rectifier is bad.

Thanks in advance.

-Clark

Wow, that picture is really shaping up. A bad selenium rectifier on the convergence board would not be unheard of. On my first CTC-11, when I unsoldered the legs on the selenium unit, it fell completely to pieces.

http://antiqueradio.org/art/RCACTC-11RectifierParts.jpg

Before it was replaced, simply touching the old rectifier, or the board nearby, made the picture go nuts.

I installed new fast-response diodes that someone sent me. I don't have the type number at my fingertips. Perhaps it is buried in a past thread.

No guarantee that this will cure your problem, but the parts cost almost nothing, and selenium rectifiers are so sketchy that I routinely replace them in radio restorations, just like electrolytic capacitors.

Phil Nelson

I don't claim to be an expert with convergence, but the first thing that jumped out at me when I saw your picture is that it appears the static convergence is off...most notably the Blue lateral adjustment. This is the control on the neck of the crt closest to the socket that moves the blue beam left and right.

I would guess that you haven't tried to perform a full static convergence yet. Using a Dot/Bar generator and set to dots, the goal is to end up with a pure white dot in the center of the screen, using the three static convergence magnets on the neck of the crt. The Blue lateral is also used to obtain that white dot. Once you've got the center white dot the rest of the screen is converged using the Dynamic convergence controls on your convergence board.

I've never seen a perfectly converged vintage color TV. I think the goal is to get it as good as you can and be happy with it. It most definitely does take some artistic and creative maneuvering to get the picture to look good since many of the controls interact with each other.

I would say if you can sit at a distance of about 6 ft. to 8 ft. from the screen and it looks good...you've succeeded.

Hope that helps......
Bob

You really need to get your hands on a degaussing coil and start the purity process before attempting any serious convergence procedures. Other wise you'll drive yourself nuts and get very frustrated achieving that "perfect" convergence.

-Steve D.

Thanks, Phil, Steve and Bob, those are all good suggestions. I did try static convergence first, and I could get the blue dot to move only so far. The lateral positioning magnet did have a large effect on the static convergence, but it's very loose when I rotate it. Is is possible that I need to reposition the convergence yoke?

I think I'll back off for a while until I get a degaussing coil and can preform the purity adjustments.

-Clark

I did try static convergence first, and I could get the blue dot to move only so far. The lateral positioning magnet did have a large effect on the static convergence, but it's very loose when I rotate it. Is is possible that I need to reposition the convergence yoke?
-Clark

If you pull the sliding magnet out of it's respective track for whatever particular color is giving you grief, and rotate it 180 degrees and then reinsert it, that might give you the movement that you need to align the beams.

You certainly can move the convergence yoke around to find the most effective position for it. Sometimes just a slight rotation right or left will bring things more into alignment. And as was mentioned by Steve, before you go any further...get your hands on a good degaussing coil and get the purity set up properly.

I finally got a degaussing coil which definitely helped the situation. I tried another stab at a rough convergence and this time I got much better results:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020610.jpg

Here are a few screen shots:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020618.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020615.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020617.jpg

As you can see from Dorothy's purple hand, I still have purity issues to deal with. I have also been experiencing intermittent horizontal jaggies (I don't know how else to describe it). You can see it in the screen shots to varying degrees. It's probably from a bad maroon drop cap from among the 20-30 that I have yet to replace. But overall, I'm very happy with how this set is shaping up. I ran it for over four hours straight last night (watched the Broncos & Patriots) and while the power transformer got pretty warm, it was never too hot for me to keep my hand on it. I still haven't measured the HOT cathode current or the HV. But they are high on my list of tasks left to do.

-Clark

On the crosshatch pattern, see how right after every horizontal line there's a little hump in the vertical line? Your horizontal wave shaping coil needs to be adjusted, that's the step in Sams where you scope the coil and turn the slug till you see equal humps.

Hi Nick,

Thanks, that makes a lot of sense. I'll give that a try.

I think that some of the edge purity hairpin magnets are missing. There is only one hairpin magnet at three of the locations on the right side of the CRT whereas there are two at each location on the left side. Are these things hard to come by?

-Clark

Hairpins should be easy to find, pair them up as best you can and don't leave single ones or they will affect the purity.

Well, I've suffered a bit of a set back. I tried adjusting the horizontal "sine wave" coil per the RCA service manual. I attached my scope to test point "E" as instructed, but the waveform appears to be the horizontal drive output, and not the the other waveform. In any case, turning the slug in the sine wave coil did not affect the waveform or the picture. Here's a shot of the waveform that I got:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020619.jpg

I don't know whether the RCA service manual misidentified the test point or if there's another problem. As time went on, I was having more and more trouble keeping horizontal lock. I also found that the horizontal hold control (which is actually the horizontal oscillator frequency control) had to be maxed out in one direction to achieve lock. I tried readjusting the sine wave coil, but it again seemed to have no effect.

Eventually, I was unable to get horizontal lock at all. I powered the set down for a while, and when I powered it up again, I got no raster and the HOT started to red plate. I knew that I still had a bunch of maroon drop caps left which I thought might be the problem, so I pulled the chassis and changed out about 10 more, including those on the video amp/AGC board. When I powered up again, nothing had improved, the HOT red plated and no raster. I'm assuming that I must have lost horizontal drive, or that the horizontal frequency is way out of whack. I tried subbing tubes, and when I put in a NOS 6AU4 damper (even the the old one tests good) the HOT no longer red plated, but I still had no HV or raster (I also tried subbing a NOS 6DQ5). I'm not sure what that means. I inspected the fly, and I don't believe that it's the problem. The only caps left on the horizontal board are two mica caps which I didn't have replacements for. I am still pretty much a novice at this stuff and I'm not sure what to do next. I'm afraid of screwing something up. Incidentally, I never let it red plate for more than a few seconds.

I'd like to be able to power up just the chassis on the bench, but I assume that that would not work without the deflection and convergence yokes attached. I may see if I can power up the chassis with everything connected but the chassis propped up behind the cabinet. That would allow me to finally measure the HOT cathode current. Anyone know if that's possible? I'm feeling a bit frustrated at the moment.

Thanks for any advice,

Clark

looks like you have a .1 not a .01 on the sine wave cap. Better make sure you are reading your cap values on the replacement correctly

did you check under the IF cover for any bumble bee caps? there is a .01 in there that couples the noise invert to the sync sep, seems like it could cause issues with sync.

I am going thru a CTC-9 now. What I do for what its worth is lift one leg of a cap, and use an old school cap tester. If the cap test bad, then I replace it, but before doing that I take the new cap and put it back on the cap tester.

Most of the time the old caps leak but you can get some indication of the value on the cap tester. By leaving all the settings alone, and trying the replacement cap on the tester, you can do two things, verify the value of the replacement and verify the replacement it good.

This step avoids 10x order of magnitude errors and finds the bad new caps. I have had a few of those yellow caps shorted when brand new.

Hi Dave,

Thanks for the feedback. I'm pretty sure that I installed all the correct cap values, but I'll double check. The troubles I'm having now started after I recapped the horizontal and vertical boards and everything was cool for a while. But I didn't check the new caps before installing them, so I could have installed a bad one. They do seem kind of cheaply made. I also have not checked the caps underneath the IF shield, so I will definitely do that.

-Clark

looks like a 104 cap on the horz board, that should be a 103

looks like you have a .1 not a .01 on the sine wave cap. Better make sure you are reading your cap values on the replacement correctly

Good call, Dave. I'm not at home now, but I compared the photo of my recapped horizontal board with Phil Nelson's and I did indeed install a .1 instead of a .01. And I thought I was being so careful:sigh: I'm surprised that it worked as well as it did. That probably explains the horizontal jaggies I was getting. I'll change it out and see what happens.

I hope to have some time this weekend to get back at it.

Thanks again,

Clark

yea been there done that, that's why I always use my cap tester to verifiy what goes in matches what came out.

...

What I do for what its worth is lift one leg of a cap, and use an old school cap tester. If the cap test bad, then I replace it, but before doing that I take the new cap and put it back on the cap tester.

Most of the time the old caps leak but you can get some indication of the value on the cap tester. By leaving all the settings alone, and trying the replacement cap on the tester, you can do two things, verify the value of the replacement and verify the replacement it good.

This step avoids 10x order of magnitude errors and finds the bad new caps. I have had a few of those yellow caps shorted when brand new.

That is an excellent idea. I will incorporate it in the future. I have gotten somewhat accustomed to the "new" way that they mark capacitors. But when I have been away from it for a while, I have to think. Very easy to make a mistake like that.

One nice thing about the "new" way is that bumblebee caps are marked the same way only instead of digits they have resistor color coded stripes.

And I thought I was being so careful:sigh:Yes, I made a similar flub on a B/W Philco just a few days ago. The comforting thing about finding those errors is that you realize you're not crazy after all -- merely human.

Phil Nelson

My cap tester is one of my must used pieces of equipment.

I just replaced a couple caps in the 9, the .01 that couples the horz osc to the horz out and a .056 on the vert. One was a orange drop, very leaky, the other was a maroon, not as bad but still leaked well below rated voltage. Others tested just fine.

Well, I've suffered a bit of a set back. I tried adjusting the horizontal "sine wave" coil per the RCA service manual. I attached my scope to test point "E" as instructed, but the waveform appears to be the horizontal drive output, and not the the other waveform.

The wave shape coil will have the drive signal coming out one side of it, and the double humped one on the other. You probably just had your probe on the wrong end of the coil, poke around till you find the humped one so you can tune it correctly or horizontal lock will have issues.

Success! I replaced the cap on the horizontal board with the correct value, but the HOT was still red plating. I pulled the 6DQ5 and found that I had a dead horizontal oscillator. After futzing with it for a while, I discovered that the NOS 6CG7 that I had installed was the culprit. It still tests fine but was no longer working in the circuit. I put the old, weak tube in place and the oscillator fired right up. This time, I was able to easily adjust the sine wave coil for the proper waveform:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020621.jpg

Now the horizontal lock is nice and stable with the control in the middle of its range. the horizontal jaggies seem to have disappeared. There are now just a few "maroon drops" remaining and things are looking pretty good:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020630.jpg

I still need to go through the entire purity/convergence set up. I discovered that none of the hairpin purity magnets are missing after all. A couple had been moved to normally unoccupied positions. I think they need to be remagnatized, too.

Thanks again for the help!

-Clark

Lookin good!

I finally had time to attempt a complete purity, convergence and gray scale set up. The picture has dramatically improved. I still need to work on the convergence:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020670.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020674.jpg

http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020676.jpg

I need to track down the source of intermittent brightness and contrast fluctuations which go away after the set has been on an hour or so. I suspect a tube socket or dirty ground connections.

Also, the image tends to smear a bit (if that's the right term for it), particularly with text. Does this point to an IF problem?
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020680.jpg

I managed to remove the safety class for cleaning. Of course, I found the VK thread on this AFTER I struggled with mine:sigh: Fortunately, I didn't damage anything.

I still need to get after the seller about looking for the missing back, but I'm not optimistic that he'll find it so I'll probably be in the market for one. What do they look like? Are they metal, like the rest of the cabinet, or fiber? If someone has a photo of one that they could post, I'd really appreciate it.

That's the update for now. I'm typing this for the second time, since my first attempt mysteriously vanished:dammit:

-Clark

Really nice job!!!!

One thing I either noticed, or missed, :D is no discussion of the wax ooze from the fly. Have you checked the HOT cathode current yet? If it's OK, do you have any plans to deal with that?

Is it a problem to have that much wax outside the fly?

Nice pictures on that set.

A CTC-7 back is fiberboard with a cardboard squarish box for the CRT neck. If you have seen a CTC-5 back, the CTC-7 seems similar to me. Mine would be hard to get into a picture, but if no one else posts one for you, I could do so.

The back on mine happened to be off, so I snapped a photo. It's perforated metal with a cardboard box for the CRT neck.

http://antiqueradio.org/art/RCACTC-7BackCover.jpg

Other cabinets might have different backs, for all I know. This is the Pensbury cabinet.

http://antiqueradio.org/art/RCACTC-7RearOpenAtPurchase.jpg

Regarding the oscillator tube that tested OK but didn't oscillate, I've had the same experience. An emission type tube tester like mine can't check whether a tube oscillates correctly. I don't know if any tester can. I have seen service books that tell you to keep swapping oscillator tubes until you find one that works.

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

Hi Phil, Chris ans wkand,

Thanks for the photo of the back and the other feedback. At least now I know what I'm looking for.

wkand, your question prompted me to finally measure the HOT current. I wasn't too worried about the wax, because the fly only gets warm after a couple of hours. So today I did finally measure the current. The reason I delayed, is that I wasn't sure if I'd have to rig up extension cables. As it turns out, it was really easy to just pull the chassis part way out to gain access to the base of the HOT. Initially, it measured 178 ma, but I was able to adjust it to about 175 ma. I get a nice, distinct dip in the current when adjusting the horizontal efficiency coil, unlike my 1968 Zenith which has a very indistinct dip:
http://i1216.photobucket.com/albums/dd366/IsthmusTV/P1020686.jpg

I tweaked the horizontal drive, which maxed out at about 180 ma. It's now about 2/3 clockwise with no signs of drive lines (and gives me 175 ma cathode current).

I'm really enjoying learning about these old beasts!

Thanks again for all the help.

-Clark

Don't read it with the current function on the meter, it'll give you bogus readings. Put either a 1 or 10 ohm resistor on the cathode and read for voltage instead, depending on which scale you want to read. I had to learn that the hard way.

Don't read it with the current function on the meter, it'll give you bogus readings.
Or use an analog meter if you have one. Digitals tend to go nuts on a complex waveform.

The back on mine happened to be off, so I snapped a photo. It's perforated metal with a cardboard box for the CRT neck.
Maybe mine is metal too, and I just spaced out. I do know I need a couple of those clips that RCA used at least into the 1970s on their backs. Mine should have three, I think, but has only one now.

Or use an analog meter if you have one. Digitals tend to go nuts on a complex waveform.

Yah, I thought about that after the fact. I do have several analog meters so I'll remeasure with one of those or try Nick's method. I was actually surprised at how well behaved the digital multimeter was for this test. Of course, that doesn't mean it was accurate :nono: I did follow RCA's instructions and place a .47 uF cap from pin 3 to ground for the measurement.

And Chris and Phil, thanks again for info on the back. My cabinet style is the "Abington." Phil, the back from your Pensbury looks like the right one. My guess is that it will be pretty tough to find one if the PO comes up empty handed.

-Clark

I believe the CTC-7AA is the late production Abington 21-CD-872-5,
Mahogany Grain Finish CTC7AA, 1958. Hope you can shed some real light on this set and get the owner to part with it. If he does, have him do a search for the back.

-Steve D.

Clark,

As I originally suggested it is the CTC-7 Abington model w/wood grain photo finish on metal. The late production CTC7 Meredith model had the all black (Ebony) on metal finish. Very similar set. I believe the Meredith sold for a few dollars less and replaced the Abington as RCA's price leader model. You should post on all the color/TV forums for a CTC-7 back ie: VK. ARF, ETF classified and any others you can think of. I believe the backs were very similar for all CTC-7 models. As the back covered only the chassis portion of the cabinet which is the same width in all cabinet styles such as Phil's Pensbury. Speaker porions in lo-boy consoles were covered w/thick fiberboard. As an option, perforated metal sheets are available at most big box home centers and can be cut to match the spec. needed for your set and then painted black. Also perforated fiberboard sheets could be used.

-Steve D.

I went and checked, and my CTC-7 does have a metal back probably the same as Phil's. Mine is a CTC-7AK Southbridge. It is on the list of projects here.

My Anderson has a metal back.

Thanks for confirming that the backs are all the same. And Steve, you nailed the ID on the set right from the start. I'm going to urge the seller to look again for the back (or let me look) before I post want ads for one. His shop is huge and he's got stuff stored in several buildings, so the original back may be in there somewhere.

-Clark

I'd go there to look in person, or at least email him a photo of the back cover. To a non-TV person, that loose back might look like a piece of anonymous junk.

Phil Nelson

Clark,

I agree w/Phil. If you can go there and can safely look around for the back do it! As Phil suggested, copy his photo of the back and take it with you. Also measure the back of your CTC-7 and take a tape measure w/you to varify size, if you find it. The owner of the shop/warehouse won't take the time to do a thorough search.

Good luck,
-Steve D.