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 Post subject: Three images side by side 1957 Zenith
PostPosted: Mar Thu 22, 2018 8:31 pm 
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Joined: Mar Thu 22, 2018 4:14 pm
Posts: 1
Working on a 57 zenith here. chassis 15z30. I have recapped and changed faulty resistors. Selenium stacks changed with diode and resistor. B+ is perfectly where it should be. One problem: on the screen there are three images side by side(not stacked) and there are horizontal lines across the screen. The horizontal hold control does not do much but I have confirmed it is not faulty. Has anyone seen this before?

I would upload a picture but can't figure out how!


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 Post subject: Re: Three images side by side 1957 Zenith
PostPosted: Mar Fri 23, 2018 6:44 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 5298
Location: Woodinville, WA USA
Your horizontal sweep circuit is running at the wrong frequency (roughly 3x the correct frequency). No need to upload a picture; it's a common problem.

If you have the Sams service manual, look for a section about horizontal adjustments. There is often a "coarse" horizontal adjustment in addition to the horizontal hold control. Follow the manual's instructions and see if that improves things.

If you don't have the Sams manual, you can get it directly from the publisher:

https://www.samswebsite.com/en/photofac ... h&s=Search

When you say "recapped," I assume you mean replacing electrolytic and paper caps, which is pretty standard in 1950s tube gear. If adjustment doesn't help and your horizontal sweep circuits contain any mica caps, you could also look at the micas. Mica caps are more durable than paper caps, but they fail fairly often in sweep circuits and other applications where they are driven hard.

Regards,

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


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 Post subject: Re: Three images side by side 1957 Zenith
PostPosted: Mar Sat 24, 2018 2:37 am 
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Joined: May Thu 14, 2015 4:15 pm
Posts: 958
Location: Dallas, TX
Actually it might be running at one third the right frequency. If you did do a re-cap, which you should have done, then you might of out in a wrong capacitor value in the horizontal oscillator.

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Tim
It's not the Destination, It's the Journey.


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 Post subject: Re: Three images side by side 1957 Zenith
PostPosted: Mar Sat 24, 2018 7:19 pm 
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Joined: Feb Fri 20, 2015 10:37 pm
Posts: 44
Location: SE Minnesota 55975
I had it happen once and it was a low voltage mica cap in the horizontal area.


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