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#1
02-15-2022, 08:51 PM
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While experimenting with shielding the filament transformer and tuner tubes, the problem went away! No more vertical distortion and only minor horizontal.
I figure something, somewhere wasn't making good contact. It's not perfect, but I'll take it.   This pretty well sums it up. 
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#2
02-15-2022, 08:57 PM
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Aw man. Now we're not going to know what fixed it.
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#3
02-15-2022, 10:32 PM
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Yeah, and there's no reason to think it won't come back. Could be a chassis rivet not making good contact, a cold solder joint, intermittent tube short...
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#4
02-15-2022, 11:08 PM
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Time for some wiggling and tapping of things.
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#6
02-16-2022, 01:22 AM
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I eliminated it by redesigning the 1st audio amp.
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#7
02-16-2022, 05:53 AM
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It looks pretty good, considering it probably never played that good when it came from the factory. LOL.
__________________
RCA VICTOR and its dealers bring you......
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#8
02-16-2022, 08:03 AM
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Dang Dude! Seldom see linearity that good on electromagnetic-deflection sets.
Last edited by old_coot88; 02-16-2022 at 08:39 AM.
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#9
02-16-2022, 10:16 AM
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Not so fast
 Distortion problem is back and a new issue has cropped up. I used to get good focus in the middle of the control but now I need to have it full clockwise. The HV box is power in a rather odd way that makes me think the two problems are related.
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#10
02-16-2022, 11:19 AM
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You sure that's not Rosemary's Television you have there?!
 
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#11
02-16-2022, 01:53 PM
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Just making wild guesses, not having really had the chance to ever work on one of these yet...
The HV circuit is clearly a free running tuned RC circuit run from main bias with a tie to the AC line, assuming the 2 HV caps were replaced, (500pf?) And guessing that other caps / resistors in the area were also changed with newer kinds, and this all could perhaps change the resonant frequency of the HV circuit, or overall behavior which could possibly include the proximity of the CRT to the chassis, and the parts in it. IE, starting some kind of weird feedback loop that just won't break. But, as stated, this is just a guess! 
__________________
=^-^= Yasashii yoru ni hitori utau uta. Asu wa kimi to utaou. Yume no tsubasa ni notte. いとおしい人のために
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#13
02-16-2022, 05:37 PM
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Heading out to the hardware store now. I'll be posting a video soon where I experiment.
I just discovered that pushing on one of the filter cap bases has a minor effect on the distortion. If I lift the CRT up off the chassis, the vertical distortion diminishes and disappear altogether at about 12 inches. The horizontal distortion is always present. The two 500pF caps are ceramic doorknobs and I did not replace them. I did replace the 12SN7 inside the box and retuned the trimmer cap. Seems to be working OK now.
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#14
02-16-2022, 07:08 PM
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What I find most confusing is that installing a shield from an Admiral 19A1 did absolutely nothing. However, moving the CRT away from the chassis eliminates the vertical 60Hz interference.
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Hybrid Mode
