Hi guys, I've been working on this Tele-tone off and on for a couple of weeks now. I have perfect sound, all the voltages seem to be correct. I have checked and rechecked all the resistors and caps, replace a lot of out of tolerance resistors. But I still do not have a viewable picture.I am going to attach a couple of photos and a link to a YouTube video I would appreciate it any help you guys can give me. https://www.youtube.com/watch?v=ze0S5Sb5_9s

Since you have very good sound, and this set uses intercarrier sound, it seems like the video IF has to be working on some level, and the video amp. That doesn't leave very many components that could be giving a problem. Check the wiring and components around the video amp stage and the route for the signal from that stage to the CRT cathode. Make sure the coils on L14 and L15 (in SAMS) are not open. Is the brightness control working properly? Does the contrast control have any effect?

Also, have you adjusted the fine tuning oscillator coil slug in the tuner for the channel you are using?

Might want to check the video detector diode (if SS type) too.

Thanks for the info, I haven't checked the coils I'm sorry to say. I will check them as soon as I get back to the shop. As for the detector, I have replaced it with a NOS. And the tuner coil has been adjusted. I am truly at a loss on this one folks. One thing that puzzled me was the 2 6al5 tubes both read low on my tube tester, as well as the 5 others I have on hand. Maybe my tester is off a bit? But I did recently recalibrate it.

Suggesting the rediculously obvious because I've been there in the past so take no offense, is the detector diode backwards?

No offence taken , the detector is a vacuum tube type so backwards isn't possible. The brightness works just fine, but the contrast affects thee sound like a tone control with little affect on raster if that tells you anything.

That all seems to point to the very few components between the video amp plate and the CRT cathode. just a few inductors, capacitors, and maybe a resistor. Those coils would be at the top of my list, as would the 0.25 uF cap which should be coupling the signal from the plate of the video out to the CRT cathode.

just wondering if you changed out several of the caps that are under the high voltage section, not the ones on the bottom of the chassis these are actually on a circuit board mounted underneath the 1b3 tube socket.

Because the HV section is kind of hard to get to, I shotgunned the entire circuit in the very beginning. Including all resistors and caps.

It looks like you replaced all the caps. And in yer video you can hear noise in the sound
as the scene changes, I'm wondering if each stage needs to be re-tuned.... Can you pick
good waveforms out along the way...? Or do you have a way of injecting signal along
the way....?

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I was completely flummoxed one time, chasing a no-video problem (Maggie color set). Sound and chroma were fine, but absolutely no luma at all. Chased the video amp stages, everything downstream of the v.detector, 'round in circles for a week. But no cigar.

After much hair-pulling, it finally occured to look at the video IFs. Sure enuff, the 2nd v. IF stage was dead. Yet the sound and chroma subcarriers were going thru by pure capacitive coupling, with no discernable attenuation.

Moral of story was to not overlook the v. IFs when there's no video but sound is still good (on an intercarrier set).

Vaveforms were my next stop on this journey. I have to unpack my test leads when I get done with work today.

Vaveforms were my next stop on this journey. I have to unpack my test leads when I get done with work today.

Frankly if it were my set, I'd do it with a redneck signal injector!

Take a small 600v capacitor, say an .005MF and hold one lead in your hand and touch the other end to the cathode (the video is cathode injected in this set) of the 7JP4 CRT and you should get a 60 cycle hum in the picture. If it is very weak, try reversing the AC plug, as that either will increase or reduce it.

Then follow the signal back to the plate of the 6AU6 Video AMP, and then to the grid of the same tube.

Then go to the plate pin 7 of the 6AL5 Video detector, and then to pin 1, the cathode.

The 60 cycle hum your body is picking up should modulate the IF stages, too, so follow it back.

You are looking for the point where the signal disappears, which sure makes finding the problem easier.

When the hum gets too strong, switch to a much smaller capacitor.

(If the signal is too strong, it may jump the defect.)

Oh, and remember this is a hot chassis set, so use due care.

Back in the late 1950's when I was servicing TVs, I used to keep several value small caps with a brass washer soldered on one end hung up on a nail above my workbench, just for this purpose. I covered the lead between the cap and the washer with spaghetti to lessen the chance of an accidental contact with the set.

James

Yah ! do what he said ! ! !

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I had a set like that, it had been recapped before I got it. turned out one of the coupling caps was attached to the wrong term on a term strip that fed the video amp tube. Like the ohters have said I would go with a video injection to isolate the loss of the signal. I use a BK 1076 video analyst.

here is a video of the defect I found.
https://www.youtube.com/watch?v=qkJ3yp0c2v4&list=UUxMsHgfGwCVtyRrqXVtll-g

Anybody remember (or ever use) the old "Buzz-it" signal injector pen? It was uber-handy for stuff like this, generating a very jaggedy, sharp-edged waveform at something like 400 hz, rich in harmonics 'waay up thru the shortwave spectrum.

Yah, we had them..... They were good for stuff like this.... Never actually scop'ed
them to see what they were putting out.....

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Anybody remember (or ever use) the old "Buzz-it" signal injector pen? It was uber-handy for stuff like this, generating a very sharp square wave at something like 400 hz, rich in harmonics 'waay up thru the shortwave spectrum.

Yeah, I've heard of them, but we did not need them.

We had old fashioned hanging florescent lamp fixtures over our work benches and the frames were not grounded. (The fixtures were industrial surplus and had been made during WWII.) These lamps radiated RF so badly that a plastic handle screwdriver touching the set would inject that signal.

As far as scoping them, that happened all the time, so we had to turn off the overhead lamps to use a scope on the set.

James

Try a modern(electronic ballast) florescent fixture if you need a broadband rf splatterer. :D Even the LED light bulbs I've tried sound like a buzz saw coming across my wireless fm intercom system. :sigh:

Electronic ballasts.... what a sad joke! I put a couple in the shop and it drives most of the TVs and AM radios wild! Ended up replacing them with magnetics!

Anybody remember (or ever use) the old "Buzz-it" signal injector pen?Somewhere in my boxes of stuff I have a "Mosquito" signal injector pen that someone gave me:

http://www.stevenjohnson.com/donbosco.htm

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

I know the one I used was not like that... Ours I think the switch was on the end like
a regular pen... The front did not have interchangeable tips that I knew of.... You pushed
the back end in and over a little and it stuck, then touch something and the noise was
everywhere.... I remember it was not my first choice tool....... It was the same size,
same looking tool.... I bet a buncha people made items like that....

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I know the one I used was not like that... Ours I think the switch was on the end like
a regular pen... The front did not have interchangeable tips that I knew of.... You pushed
the back end in and over a little and it stuck, then touch something and the noise was
everywhere.... I remember it was not my first choice tool....... It was the same size,
same looking tool.... I bet a buncha people made items like that....
Phil's link shows a pair of items, the "Stethotracer" with the interchangable tips and earpiece. It's for tracing only.
Then the companion 'Mosquito' which is an injector only. It's just about identical to the 'Buzz-it', with the same 'click & stick' pushbuton on the end, just like a penlight.

Yah, ours was just for injecting something, I have not thought about that thing in years......

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Sorry it's been so long guys. I work 50 hours a week plus 3 hours a day drive time doing component level repair on electronics for the railroads. It's almost impossible to work on my antiques during the week with only 3 hours before bedtime when I get home. I will be getting back to the Teletone this afternoon and will try all of your suggestions then. Thanks for all of the help.

Phil's link shows a pair of items, the "Stethotracer" with the interchangable tips and earpiece. It's for tracing only.
Then the companion 'Mosquito' which is an injector only. It's just about identical to the 'Buzz-it', with the same 'click & stick' pushbuton on the end, just like a penlight.

If I recall correctly, it was a "Don Bosco Mosquito." I had one way back then. It was very handy for radio or audio repairs. Not so much for TV though....

Well guys after far too long I finally got back to my old teletone. After recapping the tunerand some minor adjustments I finally have a good picture. With the sound being only about half volume but otherwise clear I think all I have left to do is an alignment.

Sorry about the photos being upside down. I guess that's what i get for drinking beer while working!

http://api.ning.com/files/KHRei0YK6cWszqsnRVjmqM1cww8koCs7YgGVgHPh5BD1RJeq4E pyyE3yB-qsVkdHzDJx3qkCtIxbKbyDBlcOf5UxCtV8NO3V/homersimpsonbeer1.jpg
Nice, that looking good