RCA CTC-11 Restoration
 

Hi all,
Here is a picture of my next restoration project, a CTC-11 "Wakeley":

http://members.cox.net/wlcarroll/ctc11.jpg

My basic plan is to first restore the power supply and to also replace any other electrolytic or paper capactors found. I notice that many of the caps are "modern" film-type that resemble orange drops except they are dark purple in color. Are these generally OK to leave alone?

I've already checked all of the tubes and replaced those that were weak or that were substituted with the wrong types. The set is working now with a decent black and white picture. Color is barely working only in the lower half of the picture, so I'm sure the purity and convergence adjustments are way off. I need to purchase a dot generator...

I have a SAMS for this set, but I'd really like to find a source for the RCA factory service manual. Would anyone know where to find one? :scratch2:

This will be my first vintage color set, so I'm sure I can use any tips or tricks that anyone can offer. :yes:

Wes

Saving another old veteran- Good for you !! Hope to see glorious "Lollipop color" pics from it on here shortly...

Those maroon caps are usually okay, though a bad one will pop up once in awhile. I would leave them alone unless a specific problem raises its head. I have an -11 and it was fairly straightforward to get running.

My favorite book for working on these was put out, if I remember right, by TAB books and is by Carl Babcoke-the RCA Color TV Service Manual. It starts off with the CTC-12 but is still useful for this set, as is the older RCA Color Pict-O-Guide. Both are readily available on the net.

Good luck!

Hi Wes: Looks great! I believe RCA went to all mylar caps starting with late production CTC-7 chassis, someone correct me if I am wrong. The wax caps would heat up and drip on to the -Y output sockets, causing color flashing. I would re-cap the power supply, and replace any other 'lytics that may be lurking in the chassis. Then bring the AC up slowly with a variac, and see what you have before going after the mylars. You may be pleasantly surprised.
BTW, I hope to finish the re-cap of my CTC-4 this week. Then on to the crt swap, etc. Hope to have it finished in time to watch old color Christmas specials.
GOOD LUCK with your "11"!
Kevin G.

Wow I had a CTC 10 and the Fisher in my Fraternity Bedroom 1973!!!!
 

I fixed up a CTC 10 which look just like yours except in had a piece of glass on it to protect the face of the picture tube. I had a Fisher 400 back then too!!! That set had great color after I replaced the caps in the high voltage section and all the tubes in that section too.

It was a freeby. Everyone was going to square screen TVs back then. Ran the Fisher with it. Hooked up the RCA in glorious mono and ran it through four speakers!! Had a Pnasonic 8 track recorder to make tapes for my frat brothers and a Sony reel to reel for me. Great seeing your pic. Cool that it works after all these years. Would love to have a roundie but we have no room. Down to 2 systems. Wife factor. Her system is wired throughout the house and my Vintage Pioneer QX 8000 is in the livingroom and a Pioneer QX 4000 is in my shop. Nice to finally have bench. No more diningroom table :D

Good luck with her :thmbsp:

eric :music:

I think the purpledrops are fine. I would leave them unless you have a specific problem.

Cool set! :thmbsp:

John

Thanks for all of the encouragement. I plan to remove the chassis this weekend to get started...

Hard to believe, but my local public library actually had a copy of this on the shelf. Just finished studying the first chapter on all of the setup adjustments such as convergence, purity, etc. Very good explanations of these settings. Thanks bgadow! BTW, it is TAB book #496.

Eric, My set has the safety glass in front of the CRT too. Hard to see in the picture.

I'll leave the purple caps alone for now and concentrate on the electrolytics first. I think I saw a few molded paper caps in there, so I'll replace those too. Watch for some updated pics (and likely many more questions as I go along).

Wes

Got the CTC11 chassis out and on the bench. Everything looks pretty good. Pretty much untouched except for some previous work on the "C1" electrolytic can. It was wrapped with lots of gooey electrical tape... Took the tape off and found the cardboard tube has split open sort of like a can of pillsbury biscuits. :sigh: Then found an old Sprague Atom cap piggy-backed to C1 from behind. Not very pretty repair work. :no:

There are also several Sprague caps that sort of resemble orange drops, but have a flat, chalky look to them. Do these tend to be reliable?

The inrush limiter is broken, which is not surprising. I'll replace it with a CL80 or similar unit.

I am still temped to go ahead and replace the purple film caps and the other orange caps along with the electrolytics. Still thinking about what to do. I'd prefer not to disturb any circuits that require any kind of alignment.

See attached pics.

look on the ac input and make sure there is not a black beauty there if it is change it. my ctc 10 had some verticle issues untill i changed all the orange drop caps on the verticle board then all was good. steve

NICE Fisher!! Is it a 500? (it is definitely not a 400).

Pardon my hijack, but are those Fisher stereos anything special? I have one that was given to me years ago. It's in great shape, and I know it works, but there isn't anyhting on the radio I care about.

Thanks, the Fisher is an 800C. Same as the 500C, but with AM and FM bands. The 500C is FM only. Very nice sound from this one after it was restored! :music:

I've made a bit of progress on the CTC11 chassis. Almost done replacing all of the electrolytic caps and also changed out two black beauty paper caps. One was across the AC input as rcaman suggested to change. For the multi-section cans, I decided to replace these with individual caps and some terminal strips. It is a very tight space to mount these between the chassis top and the IF assembly! But, with some careful planning it looks like they will all go in OK. The original cans definately needed changing as there were signs of leaking electrolyte. Plus, one of the 160uf caps had already been swapped along the way... the replacement cap had a 1969 date code.

I would like to bench test the chassis to be sure the power supply voltages are good before returning it to the cabinet. Will removing the horizontal output tube completely disable the high voltage section for testing purposes?

All of the controls will be cleaned with deoxit. Should I attempt to clean the tuner or leave it alone?

Thanks,
Wes

Yes, removing the horiz output will disable the HV. The voltages you measure on the PS will probably be a little high, because the horiz, HV and CRT draw quite a bit of current.

For alignment and so on, you can load the PS with a 2000 ohm 100 watt resistor. Probably not necessary for this though.

Dunno about the tuner. Is it strips or wafer switches?

Hey, man, thanks for blazing a trail. I'm about to start on my CTC-11. Just finished an RCA 630TS and now there's space on the workbench for the first time in months (so I'm a slow worker -- just shoot me :-).

I would normally replace all the electrolytics, but some of those in the parts list have odd values (160uf?), at least from my mostly-old-radio background. Can you recommend a supplier who has everything you need, or did you order whatnots from various people and combine (wiring in parallel, whatever) to come up with the right values? I'm used to fudging upward to some extent in radio projects, but I don't want to go too far afield, since this is my first color TV project.

Re cleaning with DeOxit, my tuner is a tad crunchy, although stable once you settle on a channel. I was planning on giving it a spritz along with everything else.

The inrush limiter on mine must be functional. The set takes a w-h-i-l-e to warm up, just like my pedestal Predicta, which uses a similar component.

If you run across any spares (ha-ha, I know) I am missing the channel selector knobs and one of the little brown knobs in the bottom row. Oh, and the dinky fine tuner knob above the channel selector.

Keep those tips & photos coming, and let me know if you run into any special gotchas.

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

I dont think anyone has 160uf. There is a trick, though. Look for high ripple current "snap in's" in 180uf. The new ones I bought have a +/-20% tolerance. Since the old caps were rated +50/-10% or something like that, the nominal is about the same.

I bought mine at digi-key. I haven't put them in yet, my old cans are still doing fine.

John

I started to try those "snap-in" caps and am curious how they would work. There were some in the Mouser catalog that were priced very reasonably but I'm not smart enough to know if they will work right for this application. My usual way of doing things is to parallel caps-100's are easy to find and then you can use 60,68, 80, 82, whatever you can find. Any of those should be close enough. RadioDaze & JustRadios are both good sources.

Mouser carries the 160uf @ 350WVDC axial caps made by Mallory. The part number is TCG161T350N2L.

All of the other electrolytics were common values carried by JustRadios. Excellent service from both companies!

I will post some pics of the electrolytics mounted in the chassis... Almost done squeezing them in there...

Looks like the tuner uses wafer switches. I guess a little deoxit in there won't hurt anything.

Thanks for the tips so far. I will report back when I do the bench test.

Thx for the tip. I love it when other people do my homework! My cap orders are in. Still haven't pulled out the chassis.

P.S. I have a Fisher 800-B in my office and a 400 in the family room. One restored, the other not. Both sound great in daily use.

Phil Nelson

My CTC-10C is still running with all of its original caps! I am amazed. I need to do some audio work, though. Lots of hum anymore.

As for the inrush limiter, mine has been just shorted out since 1975, when I got the set. Nothing has happened. What should I look for if I happen to replace it? I did install a 3A circuit breaker in the B+ line before the diodes. But thats all I've really done, other than a bunch of tubes. It still has the original 1V2 focus rectifier!

Not trying to hijack your thread here. VERY interested in your CTC-11 restore.

Here's a couple of pictures that show how I am mounting the new electrolytics. I still have three more caps to replace in this area... Looks like it may be best to relocate the two 160uf to a spot just below the rear of the tuner. Lots of room there. These are physically much larger than the rest of the caps. Still deciding which way to go.

For the inrush limiter I used a "CL-80" that came from Mouser. It is rated at 3 amps. The original limiters always break very easily and the one in my set had already been changed at some point. You can see the CL-80 to the right in the first picture below. I'll let y'all know how it works out.

Phil, I really like my 800-C! Mine has been restored as well. I have always liked the way the 800-B looks with the dual dial scales and the blue signal strength indicator tubes.

The original 160s are in the above-chassis cans, right? I don't often "restuff" original cans with new caps, unless I'm working on a Very Special set or the available room doesn't allow under-chassis replacement without using long "lazy man" leads.

Relocating usually isn't a problem, but once upon a time I created a baffling (for a while) hum by relocating filter caps too close to the RF section of a 1930s radio.

Food for thought, anyhow. I appreciate the photos.

Oh, and guess what. My library also had the Babcoke RCA book. Time to get off the computer and start reading!

Dont remember how it is in an 11, but in the next generation, 12,15,16 there are leads going all over the place to those caps. The same power supply point might be in both ends of the chassis, literally. Have a look where the wires go. It might actually be easier to put them somewhere else than underneath the cans.

Good point to bring up, because the video equivalent is to induce 60-cycle hum into the picture which appears as a slow back and forth waviness. For that reason I'm personally ascared to mount new electrolytics any significant distance from where the old ones were. Seems like a trickier prospect in a TV than a radio.

Finished up with the electrolytic caps tonight. In the picture below you can see that I ended up placing the two 160uf's below the tuner. Took out the horizontal output tube and powered the chassis up with my variac. The voltages all look excellent... Slightly higher than shown on the SAMS schematic, but almost exactly as shown on the RCA schematic. :thmbsp:

Hopefully the rearranging I did will not cause any 60Hz hum. :thumbsdn: I really wanted to maintain an original look from above the chassis. Restuffing the multi-section caps was an option, but there's no way I could have fit all four replacement caps in the original four-section cans. Could have mounted these above chassis on a PC board, but then the original look would be gone.

So, in total I changed 13 electrolytics and two black beauties. Cleaned up the various pots, controls, and the tuner with some deoxit. Some of the wiring had a very nasty, sticky film on the insulation. :sigh: Used some 3M adheisive remover to clean it up. I suppose this film was due to some sort of chemical breakdown of the insulation?

I'll slide the chassis back into the cabinet and hope for the best! :scratch2:

Nice looking work! Keep us posted. :thmbsp:

John

I'm looking forward to your updates also. Hopefully you wont have any problems with hum since the voltages appear to be right on the mark. Good luck!
-Tony

Looks like tidy work! I'm looking forward to the next chapter, too.

Phil

Well, the chassis is back in the cabinet and working quite well. See attached pic of "The King" in color and also another pic of Paul Simon. All of the adjustments on this set were way off... I now have a dot / crosshatch generator so I've been stepping through the convergence and purity settings and now have a decent picture. :thmbsp: I couldn't quite finish since the right of screen convergence settings require one of those hex-shaped plastic adjusting tools (I've got one somewhere around here..... :scratch2: ) I'm sure I'll need to run through the whole process again since each adjustment seems to affect the earlier adjustments.

I did notice the red color dropped out a couple of times... It was not an instant drop out, but more like a gradual fade out. And then would come back. Since adjusting the kine bias and red, green and blue pots it hasn't happened again. Anybody have any ideas on what could cause this?

I am using a DVD player as my program source. Some of the DVD's cause interference in the upper left corner of the picture. Is this some kind of copy guard signal? Is there some way to filter this stuff out?

Also had quite a challenge getting the vertical linearity set. It was way off to begin with and took a bit of trial and error with the height and linearity controls to find a good combination. Still not perfect, but much better now. Pretty neat how they hid these settings behind the contrast and tone knobs!

Yee-hah! Definitely looks like progress.

Phil

P.S. Any time you want to trade your cabinet for my scarred semi-knob-free piece of junk, just give me a holler :-)

Since the interference is added by the player on playback, the best way is to get a DVD player that has been modified not to add it.

http://audiokarma.org/forums/showthread.php?t=54696

John

Still having a problem with the RED color fading in and out... :thumbsdn: I'm not sure where to start troubleshooting for this problem. The picture is great when the red is working. Then it just slowly fades out until there is no red at all. Sometimes it will eventually come back, other times it takes messing with the red, green, blue and bias pots on the back. The crt hasn't been tested. Should this be my next step? I'm not sure what the signs of a weak red gun are? Seems to me that if there was a problem with the red gun, that it would always be bad.... not fade in and out. Maybe something in the color demodulator section? :scratch2:

A weak red gun would be weak all the time. Look at the crt filaments while it is happening, make sure one isn't going out. Look in the matrix tubes for the same thing. If it passes that, check the DC voltages at the CRT (avoid the focus pin), see what is changing when it goes bad.

Work your way back through the screen circuitry (if the screen voltage is screwed up, be careful, ~600-900v here). Work back through the bias circuitry if the cathode voltage is off. If it's the grid (most likely) work back through the color demod section.

Anything bad enough to remove red should screw up the DC voltages horribly. Let us know what you find.

John

John:
All of the voltages at the CRT are a near perfect match for the voltages on the schematic. The crt filaments all look good. The screen circuitry seems fine - the voltages all respond to adjustments of the screen pots.

After studying everything a bit, the problem seems to be that the red gun is working fine, but the red information is not being modulated to it. The set has a great black and white picture. The adjustment procedure with the service switch and screen pots looks normal. I have a nice full screen of red when setting the purity.

So, should I be focusing on the color demodulator section?

BTW, the problem is not intermittent anymore. I can't get an red in the picture at all now. I may try swapping the 6CG7's around to see if that changes anything.

Thanks for the help! This is my first attempt to repair a color set, so I'm learning as I go along...

Wes

Isn't the green signal derived from both the R-Y and B-Y demods? I would think if it were a demod issue that the green would be bad too...I would check the R-Y output circuitry. It may be good to try a scope on the red CRT grid lead and try and trace the AC signal back through the output tube to the demod as this may not be a DC voltage issue.

I had a CTC-7 that would flash green intermittently. I found that the wax from the -Y output tubes would drip on to the sockets. I don't think this is your trouble, as RCA started using "mylars" in subsequent chassis, from 7AA onward, but thought I would offer the hint.
Kevin G.

Spent a little time with the set today:

Chad, I have a scope here but can't find the probe... I went ahead and just checked the AC voltage on the grids with my multimeter. The green and blue were showing around 21-25 VAC. The red actually decided to work momentarily and I was able to measure around 18 VAC on the red grid. When the red faded out, the AC voltage dropped to around 14 VAC.

The chroma section is not on a PC board and is all mounted under the chassis. So, I guess the chassis is coming back out of the cabinet. :sigh:

BTW, switching the 6CG7's didn't help anything.

Kevin, You are right. I don't see any wax caps anywhere.

Thanks!

I guess it's a long shot, but do you have any way to check the DC voltages on the 6cg7 (v-706) without taking the chassis out? Maybe a tube extender? It would be a clue even if the voltages are right. I was looking at the schematic, and I think if either L705 or c731 were open, that would cut red without screwing any of the DC voltages up. If c731 was leaky, or r730 was open, it would show up as incorrect grid voltage on pin 2.

If you do find your scope probe, the waveforms usually given with RCA sets were taken with the set displaying a "gated rainbow" color bar display.

John

John:
I used a mini-grabber test lead to clip onto pin 2 of v706 which is the grid of the R-Y amp. This allowed me to test without removing the chassis. The DC voltage here shows roughly 1.5 - 2.0 volts.

For comparison, I checked the grids of the G-Y amp and the B-Y amp. Both of these show around 3.5 VDC.

All of these voltages are lower than shown on the schematic which is 6 VDC. Perhaps the lower voltage on the red is right at the threshold of working / not working?

Thanks,
Wes

My schematic also shows 6 volts (red) 6.2v (grn) and 6.4v(blue). What really matters most is the difference between this and the cathode voltage. The cathode voltage on my ctc11 schematic is 11v, so the grid bias is really -5v (red).

The voltages on the schematic were probably taken either off-channel or with a gated rainbow generator, so the absolute values might not mean much. It is very interesting that one is a little different. I wonder what the cathode voltages are?

I'm guessing, based on a cathode voltage of 11v , that -9 volts on red (versus -7.5 on blue, which is working) wont be enough difference to cut the tube off. I'll bet the peaking coil (L705) is open. It will be tough to catch it in the act if this intermittent, by the time you get the chassis out, it might be working again. If it doesn't test open, I might try bridging it. This will probably have some undesirable effect, but if it stopped the red from going away....

c731 cant be leaky, because that would make the grid voltage too high. It could be intermittently open, though. Is it a ceramic disc or mylar? You might also see if r730 is out of spec. Maybe even put a little heat on it with a soldering iron and see if the resistance reading goes wacky

John