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  #31  
Old 06-07-2012, 12:46 AM
jmetal88 jmetal88 is offline
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Well, whaddaya know! The picture tube powers up now! That was a much simpler fix than I anticipated. Now I guess I just have to make sure the video signal is getting through like it should.
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  #32  
Old 06-07-2012, 01:28 AM
jmetal88 jmetal88 is offline
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Oh, awesome! Looks like the TV has absolutely no problem with me feeding a composite video signal directly to the video output tube. I even have the picture looking pretty good, and it's quite stable. The brightness of the picture flickers slightly, but it's very watchable. Now I'll have to get myself a new 4" 4-ohm speaker and work out any audio issues. I think they actually sell speakers of the proper size at the auto parts store. The one that came with the TV was destroyed by the spider infestation that occurred while the TV was rotting in my uncle's trailer. Also still need a proper rear yoke cover. I taped together one made of cardboard just for testing the TV, but I'm having difficulty properly centering the picture, although I can still get pretty close.
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  #33  
Old 06-07-2012, 01:44 AM
ctc17 ctc17 is offline
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DC screen voltage is the easiest way to diagnose the HV section of a tube set. No need for anything more than a meter and isolates the problem. Good job on that
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  #34  
Old 06-11-2012, 03:44 AM
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I'd recommend using an RF modulator (provided the tuner and IF sections are good) as there is less of a chance of damaging the TV or the signal source that way.
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  #35  
Old 06-11-2012, 04:24 AM
jmetal88 jmetal88 is offline
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I don't think that's an option for me. I can get the TV to tune in channel 3, but the picture is very dim and barely distinguishable. So indistinguishable, in fact, that on the other stations I don't even see snow. I'd rather pipe in composite video. I'm planning on building an impedance matching amplifier I found here: http://ankythera.com/Projects/video_stage.htm
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  #36  
Old 06-11-2012, 08:56 AM
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miniman82 miniman82 is offline
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Is the AGC adjusted correctly? That will cause the picture to wash out.
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  #37  
Old 06-11-2012, 10:49 AM
jmetal88 jmetal88 is offline
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Believe me, I adjusted every single knob on the set before I even got the picture I did. It took a while before I noticed the tuner was even working at all.
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  #38  
Old 06-11-2012, 03:16 PM
jmetal88 jmetal88 is offline
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By the way, I don't think I'm being as reckless as you all believe me to be by introducing the composite video signal directly. My Photofact clearly shows a 1V peak-to-peak waveform at the grid of the video output tube, biased at -0.5V. That's so close to the composite video standard that I don't believe it would cause any damage, even with an impedance mismatch. Still, the picture has some 'smearing' in areas of high contrast, which is why I'll be building that impedance matching amplifier. But at any rate, I started a thread in the proper section of the forum a couple of days ago for general questions and discussion regarding my progress on this set. If you have anything else to add, it should probably go in that thread.
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