The Family DuMont

[Phil Nelson]

Let me chime in and agree that your picture looks pretty darned good. 60-year old TVs are not like modern plasmas. They were watched in subdued light, not bright sunlit rooms.

It's possible that you are very nearly done. As old_coot88 recommends, I'd be very cautious about turning any adjusters unless you have identified them in the manual and you have a clear plan in mind. The video IF adjustments are critical and you should not touch them unless you have specialized equipment and the experience to use it.

Part of restoring a vintage TV is learning how a TV from those days actually works (for better or worse). You might want to sit down in the evening and watch the TV for a while -- give it a little shakedown cruise. How is the stability? Are you constantly jumping up to adjust something, or can you basically sit back and enjoy the show? What's the audio like? How does the TV audio compare to audio in FM mode? (The audio is usually louder in FM radio mode on this particular TV, but the quality should be about the same.) Take some time to get used to the continuous tuner, so you know when you have found the spot where you get the best picture and the best audio. If the best-audio spot is far away from the best-picture spot, then perhaps it would help to tweak the audio adjustments. And so on . . . .

Regards,

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

[CaryLee]

I do agree that I would have preferred to not have to adjust any of the IF cans. But that ship sailed decades ago. When I brought home the set from my grandparents house decades ago, the adjusters had already been tweaked, possibly many times. I found some were turned all the way out, some turned all the way in (hence the one the "fell" into the can a couple of times. It apparently no longer has the "stop" the others do). As a result, the initial picture was not as good as it is now. It was "blocky", and had a lot of "ghosts". My grandfather was a big "do-it-yourselfer", and my mother confirmed a few nights ago on the phone that he tried to fix it himself back in the 1960's, but I doubt he ever had the SAMS or Rogers references to start with. I spent a lot of time with grandfather, and worked with him in the construction biz back in the late 70's through mid 80's. I credit my grandfather for my "gumption" to tackle new tasks. When I was young, faced with some seemingly insurmountable task, and would ask "Can we really do it?", he would say "Somebody built it." or something appropriate, and we would dig in.

I would love to have the equipment to "set it and forget it". I'm hoping to have access to an oscilloscope and signal generator eventually, perhaps borrow them if I can find someone who has them, or even if it means buying them myself. Then I can follow the alignment directions in SAMS and be done with it. In the meantime, in order to get the picture I have, I've had to spend hours looking for the "sweet spots" and learning how the IF adjusters affect picture and interact with each other. Admittedly not the best way, but right now, it's the only way I've got.

I also followed the "AGC" adjustment and horizontal sweep adjustments in the SAMS (sans the equipment for the horizontal sweep, thus relying upon my best judgment of picture, of course) and it's all been good. In fact, that alone brightened the picture immensely. It will be interesting to see, eventually, how close I got.) One of my frustrations has been that the test pattern DVD made with files downloaded from the internet works great in the computer's DVD player, but won't play in any of the actual DVD players I've tried it in, so I'm having to make adjustments with static images from shows.

We watched a few hours of "Get Smart" last night and I did notice some bright white "blips" along the "scan lines" that faded away with warm up. But after a couple hours, during an episode that had much brighter backgrounds than others, they reappeared. Looks like I've got some more tweaking to do. Also, it seems the "scan lines" appear, quite faintly, against a dark background even when the brightness is turned down quite a bit. Interestingly, in the copy of the original "SAMS" folder I have, on the schematic someone had used a pencil to circle "C2" 50uf cap, and wrote "vert jitter retrace lines".

I know this is a long shot, but are there any "old time" do-it-yourself" processes for video alignment for folks who didn't have scopes and signal generators and such? I'm kind of having to make this up as a go along, but maybe I'm "re-inventing" the wheel.

And check out that brand-spanking-new eye tube! It's action seems correct, in that it does move maybe a quarter inch up and down when it's slightly "off signal". However, when it's not on a channel at all, it lines up pretty good as well. As I get to a a video signal, it moves either up or down, and then lines up again, apparently when I reach "center" of the best signal. Is that normal? I've read where the action of this particular eye tube is not very "intuitive"..especially considering the left bar's BOTTOM edge is the one that is supposed to move up and down...and I have to agree it's pretty funky.

[old_coot88]

Originally Posted by CaryLee

I know this is a long shot, but are there any "old time" do-it-yourself" processes for video alignment for folks who didn't have scopes and signal generators and such? I'm kind of having to make this up as a go along, but maybe I'm "re-inventing" the wheel.
.

OOOY VEY!! I don't know where to even begin on this. Even a seasoned techie, if he knew beforehand that all the vid IFs had been tweaked with, would have thrown up his hands and sed "No Way!"

Back in the day there was a shop that had a proficiency test for new hires. The boss would take a set and deliberately throw the vid IFs off. The applicant was expected to re-align it using the full suite of equipment (sweep genny, scope etc.)

The fact that you've got a watchable picture on the set is nothing short of a miracle and testament to your Granddad's indomitable spirit and admonition to "dig in and do it." It's virtually fulfillment the Sea Bees' motto:

The difficult we do immediately
The impossible takes a little longer.

My hat's off to you Sir. I would never have even attempted it.

The usual symptoms of misalignment are loss of fine detail in the pic, smearing-out and ringing of the vid signal. The best advice at this point would be to not try to "improve" upon what you've got.

[Electronic M]

Originally Posted by old_coot88

The fact that you've got a watchable picture on the set is nothing short of a miracle and testament to your Granddad's indomitable spirit and admonition to "dig in and do it." It's virtually fulfillment the Sea Bees' motto:

The difficult we do immediately
The impossible takes a little longer.

My hat's off to you Sir. I would never have even attempted it.

The usual symptoms of misalignment are loss of fine detail in the pic, smearing-out and ringing of the vid signal. The best advice at this point would be to not try to "improve" upon what you've got.

There are a few "cheat" like alignment techniques. The SOP for most sets is to use a FM sweep generator(only a TV specialized version there of), an AM signal generator for markers, and an O-scope, but early on some makers published data on how to do it without the sweep generator on some sets...

A slightly better cheat (if you no gots test equipment) was IIRC was originally described for the Sencor VA-62. One can attempt to visually align the video IFs of a set if it is displaying a 'multiburst' test pattern which is basically a pattern of black and white vertical bars that become thinner from left to right. If you align your set with that pattern (and a audio test tone to make sure you don't kill the sound while working on the picture) I believe the procedure is something to the effect of get the thick bars clear, then try to get progressively thinner bars clear while keeping previous ones good.
The thickness of the bars basically corresponds with the frequency they produce so the thinner the bar the higher the frequency (it is often used to test video response in home theater applications). You could probably buy or burn a test disc with a 'multiburst' pattern cheaper than you could get the right equip for the factory proceedure.

Personally I tend to agree with coot on not messing with it any further, but if you are not worried about messing up your progress trying to get more or just want a yard stick of how good you did then the multiburst method may the thing for you...

[old_coot88]

Originally Posted by Electronic M

...but if you are not worried about messing up your progress trying to get more or just want a yard stick of how good you did then the multiburst method may the thing for you...

If i were Cary, i would absolutely stop at this point and consider it a badge of accomplishment.
If i really wanted to pursue barefoot alignment techniques, i'd get a beater set rather than risk doing it on an irreplaceable family heirloom.

[TV'S&MORE]

Originally Posted by old_coot88

If i were Cary, i would absolutely stop at this point and consider it a badge of accomplishment.
If i really wanted to pursue barefoot alignment techniques, i'd get a beater set rather than risk doing it on an irreplaceable family heirloom.

I agree. I could not have said it better myself. Since this is a family heirloom and you do not have the the equiptment to do alignment on this set call it good for now. It's not worth making things worse. the picture looks good to me. I often have to show patients and give myself and the project I am working on a rest. See bandersentv video on Dumont restoration and alignment there is alot to it. Enjoy and be proud of the good work you have done.