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  #31  
Old 12-16-2017, 11:37 AM
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<----Zenith C845
 
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Quote:
Originally Posted by WISCOJIM View Post
Huh? A roundie does not have "corners of the screen"...

.
I stand corrected. I meant to say I could not get decent convergence over every part of the round screen, although that may well have been because I was trying to converge the tube by eye instead of using a generator.
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  #32  
Old 12-16-2017, 11:54 AM
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Jeffhs Jeffhs is offline
<----Zenith C845
 
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Quote:
Originally Posted by TUD1 View Post
I set my Sencore VG91 to 45.75 MHz and injected it straight into the chassis, as I sometimes do for TV's that have lackluster tuners.

At first, I thought that I could have gotten the tuner wires mixed up, but I swapped them around and it made no difference.

I had to swap the volume and power controls by de and resoldering them onto the appropriate chassis. It "works", but I think there is a problem within the remote chassis, because it exhibited this same behavior before I swapped.
Until I saw the thumbnails attached to this post, I had never in my life seen such a weird CRT display on a color TV--and I worked on old cast-off TVs as a hobby for years when I lived in a house with a basement. I would not have thought it was possible to distort a color bar pattern that way, and I have no idea what was going on in your set to cause it. If you just swapped a couple of wires on the chassis, that should not have caused such a display. I am at a complete loss to explain why you are getting this, although I have never worked on a Zenith roundie color TV, or even Zenith rectangular sets. At this point I don't even want to guess what was causing this bizarre screen display.
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  #33  
Old 12-16-2017, 11:57 AM
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Quote:
Originally Posted by Jeffhs View Post
... One of those is the CBS affiliate on RF channel 19, DTV channel 10...when it converted to digital, that signal weakened to 9.5 kW ERP, causing all sorts of reception problems east of Cleveland, including where I live.
Jeff, you have reversed the description of the situation. WOIO analog was on RF channel 19, with the requisite high power for analog UHF. They are now broadcasting in digital on VHF RF channel 10, with virtual channel number identifier 19. When they went to VHF, they got stuck with the low ERP due to the erroneous VHF planning factors that got baked into the system and did not take into account the level of ambient interference in the VHF band.

A proportionate increase in power of all VHF stations would solve the noise problem without causing added interference between stations, but this is impractical economically due to the number of transmitters that would have to be replaced and commissioned simultaneously. It also involves international treaties regarding interference levels across the Canadian and Mexican borders.

Hopefully this will be taken into better account with ATSC 3.0 broadcasting. It is a tough nut to crack because stations cannot arbitrarily increase power individually without considering interference to other stations that do not change at the same time.
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