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Old 03-02-2017, 08:32 PM
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Vertical Centering

My recent acquisition is a '64 Zenith console, model 7500-4. I don't have the sams yet but I had a question. I was trying to make a few minor picture adjustments and found what I believe is the height control just above the brightness and peak pix knobs behind a door on the front of the set. I went to adjust the vertical centering and on the back of the chassis where it is stamped vertical centering there is just a hole. Nothing else. Where is the vertical centering adjustment? Chassis # 25LC20QS
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Old 03-02-2017, 09:34 PM
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Vertical centering is adjusted by pulling those "fishing lines" coming out of the deflection yoke up or down.
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Old 03-02-2017, 09:55 PM
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Are there two piece of fishing line exiting the yoke? If so those are your centering magnets each line goes to a separate magnet.
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Old 03-02-2017, 11:11 PM
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Fishing lines.
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Old 03-03-2017, 06:12 AM
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What is the story behind the fishing line setup? Yes there are two "fishing" lines coming from the yoke.
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Old 03-03-2017, 02:13 PM
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Those Zenith models used permanent magnets for centering instead of DC current in the yoke. The fishing lines move the magnets.
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Old 03-03-2017, 07:36 PM
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I can move the fishing line on one side. It's like a loop and I can pull one side or the other to adjust the picture. But the other side appears to be broken. Its just one piece of line sticking out. Is there any way to repair the broken side so that I can center the picture? Any help is greatly appreciated. This is a beautiful set with a good picture. I just need to get the vertical centering correct.
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File Type: jpg string2.jpg (66.3 KB, 35 views)
File Type: jpg chancellor1.jpg (77.2 KB, 20 views)
File Type: jpg chancellor2.jpg (72.2 KB, 38 views)
File Type: jpg zapper1.jpg (58.8 KB, 23 views)
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Old 03-04-2017, 07:24 AM
consoleguy67 consoleguy67 is offline
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You're right; it is a beautiful set. Once you get the picture centered, please post some screen shots.
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Old 03-04-2017, 09:55 AM
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You are right about the fishing line having a loose end being an issue. Wish I could help you one that but I've never had to take that mech apart enough to see how it works....IIRC I did have one of those yokes off to de-cat a CRT, but I can't remember looking at the centering mech.

Good luck on it! If that set has a tube amp chassis, and was in a more modern cabinet it would be my ideal combo.
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Old 03-04-2017, 10:22 AM
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very nice set
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Old 03-10-2017, 06:28 PM
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If you remove the yoke and remove the cover, you will find two concentric rings for centering. The fishing line simply is threaded through the ring.

With patience and care, you can easily disassemble and replace the line. I bought my replacement from the sports section of Walmart.
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Old 03-13-2017, 02:17 AM
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Quote:
Originally Posted by Penthode View Post
If you remove the yoke and remove the cover, you will find two concentric rings for centering. The fishing line simply is threaded through the ring.

With patience and care, you can easily disassemble and replace the line. I bought my replacement from the sports section of Walmart.
Well said & good explanation.
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