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  #1  
Old 02-01-2010, 01:52 PM
ctc17 ctc17 is offline
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My first roundie, ctc 16

The stereo works well and sounds great except for dirty pots. The tv is going to need help.
The crt was so weak there was only a very dim picture, I tried the bake with little improvement so I hit it with the light rejuve and got it back alive. Looks like every tube has been replaced including the crt with a dumont. This set needs a full setup, the purity and convergence are so far off. Also the color doesnt appear to work maybe the crystal is dead, the usual electrolytic caps as it has the hum bar and a slight hum in the sound. Also the cataract is real bad, im thinking about a Hawkeye rebuild. Are dumont crts junk? Any other recommendations?








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Old 02-01-2010, 02:01 PM
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sampson159 sampson159 is offline
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i have a ctc 16 combo also.the weave is the single stage middle lytic.easy repair.the color issue can be a mountain of things.do you get color bars when you fine tune?these chassis s have some wiring issues in the chroma circuit.also those 6gh8a s are prone to failure.saw one dumont crt in a roundie many years ago.it was a really good looking tube.dont know much about the longevity.that cataract is an easy one to peel.all in all,thiss is a great looking retro set.worth the expense of a rebuild for sure.it just screams at you-look!i am from the 60s.you will never see this much quality again!

Last edited by sampson159; 05-31-2010 at 01:17 PM.
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  #3  
Old 02-01-2010, 02:29 PM
DaveWM DaveWM is offline
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looks like your off to a good start, love the tube amp on the stereo. Does the TV audio run thru that (cant see the selector well enough to see if there is a "TV" setting). My CRT tested nearly dead on my 16, but came back fine.
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Old 02-01-2010, 03:10 PM
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Dan Starnes Dan Starnes is offline
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That is a great score for sure.
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  #5  
Old 02-01-2010, 04:13 PM
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zenith2134 zenith2134 is offline
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Off to a decent start, IMO....First thing I'd do is degauss that crt.
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Old 02-01-2010, 04:58 PM
ctc17 ctc17 is offline
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I dont hear the buss pulse when i turn it on so it may be a degaussing issue. I will check that first. The tv does not go through the amp but hey can both be on at the same time on this set. Once it has a picture it will get the stereo mod.
No color bars, nothing. I still need to test the tubes and caps

The cabinet is not wood like the zeniths, its more of a type of Formica. Im enjoying the stereo right now.
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Old 02-01-2010, 05:52 PM
DaveWM DaveWM is offline
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nice, yea I plan to do the same thing on my latest two consoles, both do not have a TV setting on the amp, but big deal, I will just go thru the aux. I know the maggies did use the amp and speakers for TV in their consoles, I guess back in the 60's Hi Fi audio in TV just was not part of the game.

My CTC17 RCA console has the standard speaker mounted to the front panel.
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Old 02-01-2010, 05:54 PM
DaveWM DaveWM is offline
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is there a tuning meter on that stereo? looks all tube based but maybe to late for a tuning eye. On my RCA it has the horz tuning eye, and a very nice receiver, I think I see at least a turned RF amp on the AM, may even have two IF stages on the AM.

From what I have read the tone arm is not all that bad. I have the same setup, it uses a felt pad to float the cart directly on the record, so you only get the 1/2 the weight of the cart on the needle. That means no adj for tracking weight on the arm. Mine had a dead cart (good luck finding one btw, hard to comeby and expensive, plus often the NOS ones are DOA).
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Old 02-01-2010, 06:26 PM
ctc17 ctc17 is offline
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Quote:
Originally Posted by DaveWM View Post
is there a tuning meter on that stereo?

That means no adj for tracking weight on the arm. Mine had a dead cart (good luck finding one btw, hard to comeby and expensive, plus often the NOS ones are DOA).

Nope no tuning eye. The bass is very impressive for 2 6x9s. Why would the cartridge go bad just sitting?

I have 3 of combos now with this exact tuner. One thing i still havent perfected is getting the stereo mpx to work right.

I have a phone that will broadcast mp3 on a radio station. Its designed so you can listen to your music on any fm radio. It sounds very good and the stereo separation is perfect.
I made an mp3 that is music in Left for 30 seconds then music in Right for 30 seconds, back and forth. Then I made another one that was one song in Left and one in Right. If I listen to it in any other stereo the separations is reproduced very well, even my Zenith combos... but these rca tuners.

Sams gives alignment instructions using an over the air signal and I can get the separation close but then the noise floor is so high its like a waterfall when in stereo mode. I have tried both the phone a good radio station with solid separation.

All 3 behave exactly the same so Im either doing something wrong or these things were never designed to work right. I know Zenith invented the Stereo MPX system we use so maybe rca had to deal with patent issues back then.
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Old 02-01-2010, 06:49 PM
DaveWM DaveWM is offline
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I use a scope to align mine you need to peak the 19khz pilot and the scope it the best way to do it. Also look around for any big .1 or 1uf caps in the path, I have had troubles there. I used a cheap rat shack MPX transmittier, a audio sine wave gen and a two channel o scope to look at L and R. you can feed one channel at a time from the sine wave generator to really see what is going on, its kinda fun after a while. There is a sep pot that balances the amount of L+R that it mixed with the L-R that is pretty critical, best not to mess with it.

One thing to really watch out for is the decoupling caps in the receiver that feeds the B+. I had a real tough dog that turned out to be an open filter (decoupler) can cap. No hum at all, so I just assumed it was ok, well it also decoupled the B+ so any audio signal riding along the plate circuit is bypass to ground. With out it you get a modulated B+ that can wreak havoc on the MPX (think L+R everywhere even in the phase inverter of the MPX).

So if you are having MPX issues and have NOT recapped every larger value cap (typically canned caps for that era), then try jumping a cap in and see if that has any effect. On mine the effect was a stronger R vs L and poor separation, no matter what I did with the MPX, and also a volume control that would not silence the audio from the radio (again the signal not being decoupled, riding on the B+ and going around the preamp tube).


all that being said prob best idea is to not adj anything unless your sure its been messed with, the caps are the most likely suspect.
My RCA's had some odd ball deemphasis on the MPX as well resulting in a more muffled sound, my guess is it was an attempt to quell the MPX "noise" that I guess was a problem, esp on a weaker station. I made a slight mode to the deemphasis caps and got a much crisper sound, if there is a weak FM station just go to mono anyway.

Last edited by DaveWM; 02-01-2010 at 06:58 PM.
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Old 02-01-2010, 09:15 PM
ctc17 ctc17 is offline
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Interesting Dave, Ill check into that.
I think the color will work on this set and it will have a fair picture once I get the filters replaced and the purity working. The red is so far off its mostly green and blue. Just need to dig the big mirror out and get to work.
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  #12  
Old 02-02-2010, 04:47 PM
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Kiwick Kiwick is offline
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Quote:
Originally Posted by ctc17 View Post
Why would the cartridge go bad just sitting?
Because it's based on Rochelle salt crystal piezoelectric elements, which are hygroscopic, and dissolve with dampness just like regular table salt

if the set or a spare cartridge was stored in a less than ideal environment such as an unheated garage or a basement, the Rochelle crystal has likely dissolved.

Some cartridges such as BSRs from the 70s had sealed crystal elements and endure damp storage better, others had poor or no sealing and dissolved even in a moderately damp home environment.

When the crystal has dissolved, the cartridge usually has some green goo around its terminals or traces of corrosion to the metal stylus cantilever.

later ceramic cartridges are totally immune from this problem.
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  #13  
Old 02-02-2010, 04:58 PM
DaveWM DaveWM is offline
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Another thing about the cart is it uses a little rubber part that engages the needle (on that one anyway prob an astatic 475) and activates the two elements. on mine the rubber had gotten hard as a rock was bent out of shape. I hope yours is ok, as they are somewhat hard to find and/or expensive (seen them for 30-60$).

The turntable drive uses a singel idler wheel. On one of mine I was able to turn the wheel on a lathe and take off about 1/16 to make it round (had a divot from the motor shaft drive) then I used a wide rubber band like the kind found on broccli (really) that fit around the wheel. Works like a charm. Since the wheel is just an idler, the diameter is not super critical, other than for making sure it falls withing the right size to put pressure on the turntable when engaged.
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Old 02-02-2010, 05:15 PM
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Sandy G Sandy G is offline
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You still have got a Jim-Dandy find, there...You're 85% home, I'd think...And just think what you're gonna have when you get her all "Squared away"...
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Old 02-02-2010, 06:23 PM
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What you can also do for an idler if the rubber has lost all its elasticity is pull the rubber tire off and roll a large O-ring on, like rolling a bike tire on the wheel. As Dave said, the diameter of an idler isn't important, just that it still makes contact between the motor shaft and the turntable.
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