1964 Zenith 5111 comes to life!

[old_coot88]

Originally Posted by Tubejunke

By mentioning the 3.58 oscillator tube, do you mean the "Chroma Reference Oscillator?

Yes. What is the tube type (designation)? Since you don't have a known-good sub, how good is the emission on each section of the tube? Try dropping the heater voltage a notch (some testers have a feature called "life test" which does this). Does emission drop dramatically and then come back slowly when you restore full heater voltage? If so, it would suggest the tube may be borderline in oscillator service. Is each section free of shorts and/or gas?

...I will get back to the issue with the horizontal efficiency coil with what seems to be a broken backbone or housing. In short, I would think that it should be rigid, but I can grab the coiled end and it wobbles around separating the windings a bit.

Yes, that coil form should be rigid and not wobbly at all. It crystalizes from heat and gets crumbly over time. Are you monitoring the HOT cathode current? It may be high since the coil is no doubt detuned from the 'dip' it was originally set to.
In Zeniths, the plastic coil forms on the convergence panel are also prone to crumbling and getting wobbly.
Bill(oc)

[compucat]

Originally Posted by Tubejunke

By mentioning the 3.58 oscillator tube, do you mean the "Chroma Reference Oscillator? That is the only color related tube that I see that is called an oscillator. The rest seem to be amplifiers and demodulators. I will have to look for a sub, but I don't have a "known good". I will get back to the issue with the horizontal efficiency coil with what seems to be a broken backbone or housing. In short, I would think that it should be rigid, but I can grab the coiled end and it wobbles around separating the windings a bit.

When I first got my Zenith roundie the horizontal output tube was glowing red at the plate. The problem was a damaged horizontal efficiency coil. The coil form was broken and the windings were loose on it. After replacing the coil the problem went away. It would be wise to replace that coil before it fails otherwise you risk damaging the horizontal output tube and/or the flyback.

[miniman82]

Originally Posted by Phil Nelson

Speaking of crystals, my CTC-7 has a funny one. The manuals show the can type, but this looks like a chubby glass mini tube with a saucer inside. Perhaps a replacement. New to me, anyhow.

The CTC-9 I had was the same way, 7-pin mini envelope with a wafer inside. I though I might punch a hole in the chassis to give it it's own little socket, but I sold it before I got around to it.

[Tubejunke]

Originally Posted by compucat

When I first got my Zenith roundie the horizontal output tube was glowing red at the plate. The problem was a damaged horizontal efficiency coil. The coil form was broken and the windings were loose on it. After replacing the coil the problem went away. It would be wise to replace that coil before it fails otherwise you risk damaging the horizontal output tube and/or the flyback.

This is exactly what mine did at first (but with smoke), but replacing the tubes I mentioned in another post brought the HV to life and the red plate, smoke etc. went away and became a nice, well aligned picture. Now I don't even want to turn the set on!

Where in the world can I find an original replacement for THIS, or is it unobtanium?

[Tubejunke]

Originally Posted by old_coot88

Yes, that coil form should be rigid and not wobbly at all. It crystalizes from heat and gets crumbly over time. Are you monitoring the HOT cathode current? It may be high since the coil is no doubt detuned from the 'dip' it was originally set to.

No, I have not checked that. Another person has posted saying that his set had similar problems and that the coil should be replaced. Would I use an amp clamp or break a connection and connect an ammeter in series to check this current?

[Tubejunke]

Originally Posted by old_coot88

Can you post a schematic of the color section? I'm betting that the problem is something other than the crystal, based on your statement that the color was strong and in sync prior to the sudden drop-out. Bill(oc)

I tried to attach the PDF of the whole Sam's folder for this pupose and for anyone who might like a copy, but the file exceeds the filesize limitations of this website. PM me with an email address and I can do it that way.

[DaveWM]

the easiest way is to use an adapter that plugs into the HOT socket, and the tub plug into it, there are two leads that come out, you connect a milliamp meter there (bypassed with a 1uf cap). use an analog meter. some folks use these in the audio world to check the bias setting of output tube.

Or you could disconnect the jumper wire that is used to connect the cathode to the chassis and insert the meter in series there, again use a bypass cap and analog meter.

[Phil Nelson]

I posted the schematic in two parts at these URLs:

http://antiqueradio.org/art/temp/Zen...Schematic1.jpg

http://antiqueradio.org/art/temp/Zen...Schematic2.jpg

Big files, so I would right-click on the URL and save to your computer for easier viewing.

Looks like the chroma reference oscillator is a 6GH8.

I'm not going to keep those files up there forever, so get 'em now if you're curious.

Regards,

Phil Nelson

[old_coot88]

Yo, way to go, Phil. Now we got a good eyeball at the color section.
To the OP: The "reactance" coil mentioned earlier is L28 (adjustment A17). Check that coil for continuity. It's a very frequent failure point in RCA and clones, and may be in Zeniths also.
And check the plate and screen (G2) voltages on the 6GH8.
A good direct sub for the tube is 6EA8, and in a pinch, 6U8 just to see if the oscillator is gonna run or not. And here's some other possible subs:
http://www.nostalgiaair.org/tubes/6gh8.htm

[Tubejunke]

Just an update to let everyone know that this thread and the set is not finished. CTC17 was nice enough to send me a crystal that we hope will rectify my sudden loss of color. I simply have not had the time to proceed with repairs! Since I last posted, I have been faced with the punishment of final exams in my electronics degree program that I have been working on for two years. I managed to graduate on May 15, 2011 with a 4.0 GPA, and hope to someday actually work in the field that I have always loved. The prospects are sort of thin as the bulk of employment for electronics technicians has shifted largely to industrial repair. Unfortunately, the country has sort of turned it's back on it's own industrial base, so many (most) of those opportunities have disappeared. Frankly, my interests would be more that of a bench technician than that of a guy with a multimeter swapping out start/stop stations, motor starters, and tweaking photosensors. I was just born way too late I think! Just 10 or 15 years ago a guy like me could graduate and go to work for places like Tandy who actually still had repair facilities to support their products. My best friend's brother worked for them for 15 years after graduating from the same program as I have, but they shut the doors, and needless to say he is not all too happy working in a motor/drive repair business, which would be the closest thing to bench repair left I guess. I would love to work for such a place, and even went as far as to ask one to take me on at a greatly reduced wage, sort of like back in the days of apprenticeship, but the plan did not work! This is not a rant as I am proud of my achievements and if nothing else the knowledge I gained will make me a better hobbyist.

[Tubejunke]

I am bringing this thread back as page 2 has the pictures that many people want to see of the set that is for sale. I never had time to fix the color issue and the super sharp black and white picture is a little jittery, so I think some recapping of at least the horizontal deflection circuitry would be in order before the set is put to good use. I REALLY want to sell this set least of everything, but the right deal will take it. I meant to make room by getting rid of other sets and radios to justify keeping this beauty and getting it set up for fairly regular use. Although I am a TV hobbyist, I will never understand alot about desirability with old sets. To me a 1964 color set would not be all the rage as I have much more interesting things to let go of. I never found a home for my 24" 1958 Space Command and may never find one. To me a 50s set with a large screen and remote control would be more interesting and out of the ordinary than the 1964 color set. Same with my 1947 RCA 8T-243 as far as being interesting, but I feel that it will find a home because there are the collectors who are just into early small screen stuff. The 50s to me all to often gets overlooked and some of the most interesting and best looking, and best performing sets came around the mid 50s. I am hoping that one of the many interested parties will simply come with a van and do a 'bundle' package deal so I can concentrate on only a few favorites that I will keep.

[DavGoodlin]

As an electronics degree engineer, I feel your pain. Even in 1988 when I graduated from College in Maryland, there was little employment in electronics beyond government defense contractors. The electrical power industry (power plants, solar, wind and distribution in facilities) seems to be the only future for us. Boring yes, but its a living. Your degree will help at work but this hobby will keep you sharp on the theory.

[Kevin Kuehn]

Hi Tubejunke,

I was pleasantly surprised to see this thread up at the top. A friend in the TV/appliance biz dropped one of these 25LC30 chassis Zeniths off for me to enjoy last night. This one is a model 5119. I'm sorry to hear you've lost interest your set, but I understand how that can happen.

I also graduated with a technical electronics servicing degree back in 1984. Same deal- always dreamed of fixing quality consumer electronics. Ended up working in the electronic weighing industry for 10 years before finally talking over the family business (non electronics related). I still long to be back on the bench full time, but the jobs just aren't out there. I think if a guy was located near a large enough population, that one could carve out a humble living repairing pro audio equipment. But lately I've been noticing even that market moving to cheep overseas manufacturing.
The electronics business in this county has sure turned into a sad state of affairs.

Anyhow... below are a couple pictures of the set I adopted last night. Not sure what I'm going to do with it right now, but I'll for sure enjoy looking at it for a while. I hope you don't mind me posting them here. If it's for whatever reason a problem I will gladly delete.

Best of luck with selling some of your items.

[Electronic M]

Kevin, I believe I have a spare tricolor on-off-vol knob laying around that might fit that set.

Some day I'll own a Zenith roundie, ain't no one gonna stop me when I find one for the right price.

[Kevin Kuehn]

Tom,

I do have that knob, although it's cracked around the stem. I think it can be glued.