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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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!

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.

That is a great score for sure.

Off to a decent start, IMO....First thing I'd do is degauss that crt.

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.

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.

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).

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.

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.

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.

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.

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.

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"...

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.

Update...
One lead to the degaussing coil was loose and hanging. Got that hooked up and worked on setting up the convergence and purity for awhile.
Got a fair bw picture. I do get some kind of color, mostly a yellow green if I turn the color all the way up and mess with the fine tuning.
Got caps and a color crystal today, will pull the chassis and replace on Saturday.

I got this set setup in a 2 bedroom house we have for rent. When perspective tenants come to look the set will be playing in the living room. I have been using the stereo along with my satellite radio while we are working on the house. Escape is the perfect channel for this vintage of combo

Don't forget to try the 6GH8's first - they'll check fine on a tube tester, but fail as a color burst amp/oscillator. We used to use those RCA's to actually test used 6GH8's - if it worked in an RCA color circuit, it was considered good.

Their use in color circuits was probably a stretch - they were originially designed as horizontal oscillator tubes. There's a big difference in 15,750 Hz and 3.575945 MHZ!

Cheers,

Color TVs were not the first time manufacterers tried to stretch a tubes design characteristics. There are many early AM/FM radios that use a 12BE6 for both bands. The better ones used a 12AT7, etc.

update2

Tested and replaced all bad electrolytes. I changed the crystal anyway because I got a new one here and I had the chassis out. Now I get the rainbow that rolls up and a nice solid bw picture. Will test the tubes next. I know im going about this kinda backwards..

Their use in color circuits was probably a stretch - they were originially designed as horizontal oscillator tubes. There's a big difference in 15,750 Hz and 3.575945 MHZ!


I've wondered if 6GH8's were used for anything other than color circuits. Don't recall off hand if I've seen them in sets doing other jobs. My "used tube" buckets always have a lot of them in there.

I attempted getting my color to lock in on my 15 years ago by replacing the 6GH8... must have gone thru 3 or 4 before finding one that finally worked... and they were all NIB tubes.

I have seen GE B&W sets that used 6GH8s as horizontal oscillators. Zenith may have also used these as horizontal oscillators.

I've seen them used in place of a 6EA8 in Zenith tuners before too. Had a roundie with one in the tuner. It worked fine.

I have seen GE B&W sets that used 6GH8s as horizontal oscillators. Zenith may have also used these as horizontal oscillators.

I think Zenith did use them in some of the 70's B/W hybrids for a horizontal oscillator IIRC.

Got color. I switched the two 6gh8 and color came in. I tested them too, even cut the filament voltage back to 4.5 and they tested good. No leakage, no shorts. They both tested good...guess its just that sensitive.

Had to adjust the sound coils because of buzzing. Ok picture but noisy. Like a weak signal. I bet the set needs a full alignment if the sound coils are any indication.

Anyone here ever done a total if/rf alignment successfully?

I attempted getting my color to lock in on my 15 years ago by replacing the 6GH8... must have gone thru 3 or 4 before finding one that finally worked... and they were all NIB tubes.

'tain't just tubes that have personality conflicts - on of my laptops suddenly died. I popped out one of the memory cards and it worked just fine. In fact it worked with either, but not both. Had to replace them (they were the originals) to get the computer to work as it should.

If you think 6GH8's are bad, the 5GH8 was no better - and between RCA and Westinghouse/Penny's sets, there were plenty. I've seen many a RCA 19" color set fixed by just moving 5GH8's around between the sync/color/horiz circuits in the set.

When I worked at an electronics distributor in the early 80's - we sold 6GH8's by the sleeve of 5 - not because the shop needed to replace that many, but because they need that many to replace one - Charlie, it seems, you too!

I would check the RF tuner tube 1st as well as some new IF tubes before going anywhere near an alignment.

I just had a lapse of sanity and bought this (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170439017655). What do I need besides this (if will even work for tv alignment) ?

I really want to be able to do good alignments on my old sets and have them come out right. I checked all the tubes and even subbed most all of them. The sound was so far off the video has to be off to.

yea I hear ya, alignment just leaves a bit of a sour taste in my mouth.

I decided to mess with IF alignmnent on my last B&W. Of course I had no equipment so I attempted to do it by ear and eye (:no:)... anyway the plan was just to turn each lug just a bit and keep up with what I had done. That plan fell apart pretty quick, then one of the coil forms broke apart....

I ended up making a new form thread so the slug would tune. Then I got a B&k 415 sweep gen with markers (very nice). I started by confirming the marker freq with a freq counter. Lots of hookup cables and trial and error attempts I was finally able to get the right shape and markers in the right place.

I think it just take a lot of practice to get it right, and to know when ot stop.

The Biggest problem I think it the fragile cores, that being said I completely understand your wanting to do it :yes:

You just want to be absolultly sure its really the problem. Of course the best way to know that is to get your equipment working properly and then go ahead and sweeep the circuits, if the bandpass looks right then dont touch a thing, least something breaks and set you back, 1st do no harm.

In the end my B&W problem turned out to be a keyed agc with an open cap letting horz freq pulses get thru. The agc voltage was correct per the DMM but when you looked at the scope you could see it plain as day.

For your marker gen I would suggest you get a freq counter and check it out.

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on thing I learned is the test equipment itself can mess up the curve. I had an ill shaped hump, turned out to be the clip on the TP was close the the IF coil, it made a HUGE diff just moving that clip around. Tubes effect it as well. One time it turned out to be an intermittant IF coil connection (prob due to all my fiddling). Considering the RF freq are so much higher than the IF, there is no way I would get near the tuner for alingment, not really needed anymore do the the lack of OTA analog signals, most of my watching is on channel 2 or 3 whcih ever works better.

I really wanted to do an IF alignment just to see how it works and I like to learn new stuff, from that exp I learned to respect IF aliignment but not fear it. Still I would only do if if all else checked ok AND the sweep proved a problem as is AND I was pretty darn sure I had the hookups right.

What I found very helpful was to hook up to another chassis (hopefully the same model) that is working well and sweep that. That a good way to validate the hookup and how it should look. What I found was while the waveforms were sorta like they should be, they were by no means perfect looking yet the picture was fine.

From this I deduce, the IF curve was not as critical as I thought (at least on a B&W set) or my connections were impacting the curve. I suspect the latter since minor repositioning woudl alter the results. I tried to get the wave as near as possible on the working set, noted the cable setups, then returned to the non working set (after I goofed it up) did the exact same deal with lots of care on lead dress, and then lots of patiencd on AGC bias and RF power to get the hump to not clip. I ended up with less gain but better looking bandwidth. The result was a near perfect pic that look pretty much the same as a direct feed of the composite signal at the post detector TP.

Which brings up a second point, I would recommend you do a composite video feed directly at that TP. that would isolate the issue to before or after the IF section.

Dave, walk me through the alignment. How fast of a scope do you need? From reading the sams it looks like you start with the marker and null then peak some slugs. Then add the signal generator into the scope and the mixer and adjust the waveform.

I have plenty of sets to practice on. I have a cbs bw that I already tweeked by eye and even though it has a good pix I know its way off.

Im definitely not going to touch this for awhile. Would just like to get the equipment and learn how

Gave Hawkeye a call on the crt, $380 to rebuild it.

any old scope will do, you dont need a fast sweep, in fact since your sweeping the detected signal the scope will prob be looking at 60 cps.


I followed the sams, yes it had me set the traps 1st using a vtvm, then the markers on the curve. The vtvm was wierd is said set for a min reading, but that was odd since it seemed backwards that is the it worked better when set for a max, of course maybe I had it reading a min neg which would have been the highest pos, the the lowest neg. I got confused on that part.

the other thing is how to inject the signal, here I followed the instructions, found a old osc tube, cut a grid pin off (hated doing that) used a tube shield wrapped with some paper to isloate from the tuner built in shield. there was a TP just after the detector (this one used a mutipupose tube, some use a SS diode). this is where I had trouble, since on one of my sets the TP was INSIDE the sheid of the IF coil. I had to remove the shield and use a clip on the TP, it was very critical on placement. The Emerson had a better layout.


dont for get to use an AGC bias, the B&K 415 has 3 adjust bias supplies. just make sure you getting neg at the AGC point. I think I started out with about
-3vdc with respect to ground.

you start the sweep and adj both the RF ouput/sweep/AGC bias all of them until you get the unclipped humps. It takes all 3 and is a real balancing act.

If you clip at all it will give false readings so adj to just the point where clipping stops.

turn on the markers (on the 415 you can turn on several). On my sweep gen there is a phasing adj that lets you center the hump otherwise you may get the end of one and the begin of the other hump.

the Sams should tell you what coil does what, have fun.

I just ended up using the markers for setting the traps rather than the vtvm approach.

When your done, try for grins swapping IF tubes (assuming they are the same of course) and watch how it effects the form. Since gain will always be different you will no doubt see a swap since its almost impossible to the humps to be the exact same size.

If you have analog transmisson on reg stations you may want to touch up the traps by eye if you have interference from adjacent channels.

If you want to see some scope patterns go to my thread on vintage tech on IF alignment.

http://www.videokarma.org/showthread.php?t=246854

The sams talks about using a signal generator and feeding it into the horizontal of the scope as well as the set. Where does that come in? or does the bk do that?
You cut the grid pin off to killl the osc?

I was looking at the factory service manual on that zenith combo we both got and the alignment is totally different from the sams. They say put the tuner between two channels to kill the osc. (if i can remember ill take that book and photocopy it for you, i think you would enjoy it)

The sams talks about using a signal generator and feeding it into the horizontal of the scope as well as the set. Where does that come in? or does the bk do that?
You cut the grid pin off to killl the osc?

I was looking at the factory service manual on that zenith combo we both got and the alignment is totally different from the sams. They say put the tuner between two channels to kill the osc. (if i can remember ill take that book and photocopy it for you, i think you would enjoy it)

The B&K does that it has a horz scope out but I dont really think its an issue.


My scope does not have a horz drive just a source for triggers. If your scope has a horz drive input then you can prob reverse the sweep direction, and get a mirror image. On mine the wave pattern was reversed from the direction shown on the B&K and I had no way to correct it. You just have to remember that, easy to tell by flipping the markers on and off. on mine the low side was on the right, while on the B&K is shown on the left.

Guess that makes since if the osc coil is shorted or open mid channel. Better than destroying a tube for sure.

Buddy of mine told me to install a ferrite bead at the end of my coax feed that attaches to the tube shield. I got one of those you find on some computer or VHS tape AC power leads, the kind that clips on.

also note if there is any resistors put in series with the TP's