RCA CTC-11 Restoration

[blue_lateral]

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

[bgadow]

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.

[wcarroll]

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.

[Phil Nelson]

Originally Posted by wcarroll

Mouser carries the 160uf @ 350WVDC axial caps made by Mallory.

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

[holmesuser01]

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.

[wcarroll]

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.

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, 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.

[Phil Nelson]

Originally Posted by wcarroll

Looks like it may be best to relocate the two 160uf

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!

[blue_lateral]

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.

[David Roper]

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.

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.

[wcarroll]

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.

Hopefully the rearranging I did will not cause any 60Hz hum. 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. 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!

[blue_lateral]

Nice looking work! Keep us posted.

John

[Tony V]

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

[Phil Nelson]

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

Phil

[wcarroll]

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. 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..... ) 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!

[Phil Nelson]

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 :-)