Zenith 1958 chassis 17A20 questions

[kramden66]

Ok my first is why does this set have such a flat audio sound ? anyone know ? is there something I could do to get some bass out of it ? I thought maybe the speakers but hooked it to an external source and nothing , its shocking since its a console with double speakers or is it made that way to get you to buy the one with the hi fi emblem and separate treble / bass controls ?

the other thing was it pulls a little horizontaly on the left side of the picture , I tried the width sleeve and that really kind of pushes things in the center , makes the pull a little less but not gone , there is no horz lin control unless I'm missing something , I will look over the schematic , this issue is not a big one but if one can improve on something why not try

mike

[Kevin Kuehn]

Does the horizontal hold control have any affect on the left pulling? The Sentinel console I've been watching has a really wide horizontal hold range, but if it's adjusted too far off to one side, I get a funnel shaped pulling on the left edge.

[kramden66]

the horz hold really doesn't have an effect on it which on these type of zeniths is the horz frequency control , the width sleeve helps a little but will also crush things in the middle of the screen if pushed to where the left side that's pulled is made to look more normal , I will open it up again and just recheck everything in that circuit , right now its watchable its just that things on the side get stretched, as far as the audio my friend said recheck the resistors there and take the electrolytic C2C and increase it from 20uf to 100uf that should make a difference even if not a huge difference any improvement will help , plus I could change the audio output transformer but no clue as to what I should change it to or with.

mike

[DavGoodlin]

The audio could be affected by an open bypass capacitor on either the screen grid (G2) or cathode by allowing degeneration. Also check your speakers to see if the voice coils are moving freely. I had a Zenith radio with this issue and wetting the cone, letting it dry facing down made it sound like new.
Nothing comes to mind regarding the sound IF amp or ratio detector stages causingthis issue.

[kramden66]

not the speakers at fault because I tried hooking it to separate speakers , I will take a look tomorrow - I hope

[Tubejunke]

You are lucky to have yours going as well as it sounds. Don't get me wrong; I have heard that they are outstanding performers. I just had bad luck with my 24" Space Command. Never got anything but volume adjustable hum for sound and almost no vertical sweep after a complete recap. It was likely a couple of separate problems outside of resistors and capacitors. It had to be really, but I lost interest after all of the work on what looked like an almost unused chassis with all stock tubes. I thought it would be a cinch due to that aspect alone. I do remember finding an open coil and diode in the video detector circuit, but I was pretty much done by then.

I tried to find a home for the set, but found no takers. So I have a complete chassis you could eat off of, and all the remote stuff, tuner too if you need anything. That should be a good candidate for a regular use set if you treat it right! Oh, BTW there is a "buzz control" on the back of that chassis or should be. Have you tweaked that any?

[Tubejunke]

You are lucky to have yours going as well as it sounds. Don't get me wrong; I have heard that they are outstanding performers. I just had bad luck with my 24" Space Command. Never got anything but volume adjustable hum for sound and almost no vertical sweep after a complete recap. It was likely a couple of separate problems outside of resistors and capacitors. It had to be really, but I lost interest after all of the work on what looked like an almost unused chassis with all stock tubes. I thought it would be a cinch due to that aspect alone. I do remember finding an open coil and diode in the video detector circuit, but I was pretty much done by then.

I tried to find a home for the set, but found no takers. So I have a complete chassis you could eat off of, and all the remote stuff, tuner too if you need anything. That should be a good candidate for a regular use set if you treat it right! Oh, BTW there is a "buzz control" on the back of that chassis or should be. Have you tweaked that any?

[kramden66]

yes I tried the buzz control , I went over all resistors and nothing bad so I tweaked the quad coil from both top and bottom and then the if coil from top and bottom and got it to where its almost completely silent from text buzzing , I wonder if it was a good idea to use a 6aw8 half for video out and the other half for sound , maybe some video noise leaks through.
I did improve the audio , no bad resistors there but took the 20uf at 25 volts and changed it to 100uf and that made an improvement but it still is a bit lacking in bass , probably because it is such a small audio output transformer , I may pull a bigger one from another set or radio and see what it does with that added or I may just leave it
yeah its perfect for dvds that don't look the greatest or tapes , looks better on it then trying to watch on a high def set and stuff that looks nice or great on the high def set looks pretty darn good on the zenith .
when I get the chance I will compare part numbers to see if yours are the same and I will get various parts from you to have incase something should fail , the 24 inch would have been cool to have and use but I'm happy with the 21", not sure if I ever had a set with such a shinny chassis , was kept in a good environment for years.
you sure your vert tranny was ok? that could knock out the vertical , you gotta love the long shaft for the contrast , what was the purpose ?

mike

[Tubejunke]

If your set looks anything like this, then I am certain that I have anything you would need. You will find that they used the same chassis for years beginning in the late 50s. We both seem to have (had) sets that were extremely well kept and probably not used much. I remember testing my crt and it was SUPER strong. No black dust in the HV cage either!

Just let me know if you need anything and good luck. You should "Google" 1958 Zenith TV pictures and click Images. There is a 1956 floor model out there that is really neat looking. If I had that one I would have kept it just as a decoration if I couldn't get it going. I am regretting scrapping my set more and more, but what's done is done. Just too many projects, too little time, and far too little space......

[kramden66]

close I had a 21"just like that with a pretty dead crt , traded it off , here is the one I have.

http://www.videokarma.org/showthread.php?t=260014