#1
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CRT Issues
I've been seeing two problems on a 1994 BPC Panasonic set I have.
The first is a bending of the top few lines of an image. The other is an impression of an image to the right of anything bright or shiny. Is this a CRT issue or something repairable? |
#2
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Not CRT issues, in my experience. The bending may just be a horizontal-hold/frequency adjustment internally. Did you have this set working without these issues in the past, or did you get it this way?
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Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did." |
#3
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I think the shadows to the right weren't there before. Not sure about the bending.
The set had an issue with a bad joint in the vertical IC that would compress the picture periodically. A whack also temporarily fixed it. |
#4
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edit.. delete after re-looking at the pic, top looks like a bit of "flagging" used to be common with VCR playback and certain TVs. Horizontal timing I recall was the issue.
Last edited by Ed in Tx; 01-18-2016 at 07:53 AM. |
#5
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Do all video sources show the bending? Is the ghosting/ringing equal with composite-video as well as S-video and RF inputs? It could be something like loose grounding/shielding or wiring in the video circuits.
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Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did." |
Audiokarma |
#6
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The bending doesn't happen on all sources, as far as I can tell. The ghosting does happen with all sources though. Capacitors?
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#7
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Yes, bad ones in the video circuits could cause that. I would expect to use an oscilloscope and trace input signals through the set at this point.
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Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did." |
#8
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All sets can show a little bending at the very top with VCR playback, even those designed after VCRs came into use. It will vary with different tapes and VCRs. If it is within the first few percent of the raster, just turn up the height a little to hide it off the top of the screen. If it extends very far from the top, check the capacitors and resistors in the horizontal AFC section.
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#9
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Quote:
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Tom C. Zenith: The quality stays in EVEN after the name falls off! What I want. --> http://www.videokarma.org/showpost.p...62&postcount=4 |
#10
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It happens with DVDs too. Is the ghosting bad caps too?
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Audiokarma |
#11
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I have a couple of late Panasonic tv's and they have a number of bad solder joints
that have caused all kinds of strange behavior. One of them had bad connections along the tuner, kind of a unit by itself, lots of bad connections caused a lot of the poor definition I see in your pictures, especially the "stop" Picture. If not all devices have the bad look, then you might have to look into the impedance matching transformer and the other stuff inside the tuner near the input. .
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Yes you can call me "Squirrel boy" |
#12
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How can I start diagnosing/working on the problem?
EDIT: There's only one input, the coaxial RF. Last edited by Outland; 01-19-2016 at 08:25 PM. |
#13
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If there is only an RF input, a small amount of that kind of ghosting on fine details may be normal; also, any set made in 1994 with only an RF input is by definition a low-end set, so again it will not have the picture quality of higher-line sets.
__________________
Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did." |
#14
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If it was my set, I would look inside for the horizontal-hold/frequency adjustment and try tweaking it, and not worry about the ghosting at all.
__________________
Chris Quote from another forum: "(Antique TV collecting) always seemed to me to be a fringe hobby that only weirdos did." |
#15
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Noted, I'll do that.
Thanks all. |
Audiokarma |
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