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 Post subject: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 11:49 am 
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An interesting thing I had just thought of is wondering if antique TVs (such as the RCA 630 chassis) could be modified to work with modern HD video signals to produce a higher definition picture than standard definition. Such modifications I would imagine would be increasing the horizontal and vertical scan frequencies to produce faster frame rates and lines of resolution. I also wonder if there are any kind of converters that would take an HDMI supplied signal to convert it to analog at higher than standard definition that could drive such a modified TV. OF course, video and audio would be supplied to the appropriate amplifiers in the set, bypassing all RF and IF circuits. Any thoughts?


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 12:34 pm 
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2nd question: You can buy scan converters. Most of them have various video outputs, like composite, component, S etc, with various inputs like HDMI and all the other computer scan rates. Extron made several, like the VSC 700.

1st question: Making a vintage TV function at a higher scan rate? Uh, no. Then again, NO! It would require a total rework of the horizontal circuit.


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 4:31 pm 
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What Johnnysan said.

The video and trace amplifiers have to be tuned for peak performance just for the old standard signal. Additionally, modern TV signals are digital, not analog.

A converter is the way to go, such as:
https://www.amazon.com/ViewTV-AT-163-Digital-Converter-Player/dp/B00GGVPKKC/ref=sr_1_11?ie=UTF8&qid=1510154898&sr=8-11&keywords=tv+converter+box+digital+to+analog


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 5:19 pm 
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Would be similar to modifying an AM radio to pick up FM. Possible with many new parts, worth it? > up to you
if you're short of challenges. :)

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 6:08 pm 
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You can buy a tiny NTSC camera for about 10 bucks. You could point it at
a HD screen, feed the output to video modulator and connect that to the 630
antenna.

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 7:26 pm 
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Location: Lafayette, CO
Ever seen a -630 (or sets of the same design) properly aligned and set up? Not bad at all, you can see why these sold. Time marches on..Craig


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 9:27 pm 
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Well here is what needs to happen to do that.
The tv tuner and I.F. have to go bye bye. Next the video amplifier has to have a much wider bandwidth well over the 4MHZ on the better sets. Next the sweep frequencies have to be raised. This will be the biggie. If you look at crt computer monitors that can display these type images can change the sweep frequencies to suite the need. The old yoke flyback and and vertical output transformers were not designed to do it. Your horizontal output current would most likely soar putting a heavier load on the power supply. Now the sets with electrostatic deflection may be easier to modify because the H.V. suply doesnt have to change. The sweep systems could be changed as those sets are basically oscilloscopes with the video fed to the Z axis. I am not sure if the 7JP4 etc. can focus down to a fine enough spot to show the detail. Best thing to do is get your set primed up for standard T.V. as it was designed and use proper techniques to ensure video injection in place of the video detector and this means proper phase, level, and D.C. coupling if the video amplifier is so coupled to the detector and crt. Feed the sound likewise around the audio detector. To flatten the video response eliminate the 4.5MHZ sound trap in the video amplifier as it is no longer needed and will allow the highest quality fine detail the standard set can produce.


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 9:42 pm 
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I am devoting significant resources to help me get control of my persistent propensity to indulge in redundant verbosity while providing answers that go beyond and are perhaps even irrelevant to the original question.

The answer to your question?

No.

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 10:30 pm 
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The Japanese Hi-Vision system of the 1990s was an analog HDTV system that was a bit along the lines of what you are proposing. I saw some demonstrations of it in Japan back in the 90's, and the pictures were very impressive.

A hobbyist could modify an antique set for higher horizontal scanning frequency and experiment with higher definition images. It would be a big project, but not necessarily beyond the capabilities of a motivated experimentalist. Modifying the horizontal deflection system for 2X or 4X scanning rate would be challenging, but if one were willing to build new deflection amplifiers from scratch (using the existing deflection system only to generate the HV) it ought to be possible. I'm not sure what the upper limit for an existing deflection yoke would be, but I understand some computer monitors had quite different scan rates than standard TV, so there may be some existing yokes and deflection systems out there that one could build upon.

Combining both higher resolution and higher frame rate would make the project especially difficult. I'd choose one or the other, but not both.

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Wed 08, 2017 10:41 pm 
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DaveD wrote:
I also wonder if there are any kind of converters that would take an HDMI supplied signal to convert it to analog at higher than standard definition

I'm actually doing something like that right now, although I'm not sure that the resolution is up-scaled to any degree.
I have a switching box to select between my ROKU media player and my DVD player, both outputting via HDMI. One of the box's HDMI outputs goes to the big screen TV above it, the other to a device that converts it to composite video (bought at Amazon for a few bucks). The composite video goes to the input of a VCR. It's coax output then feeds a TV located in another room, connected by an RG-59 cable in the attic and walls. Although the remote TV is a flat screen, this does work with CRT TV's as well.

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Thu 09, 2017 6:13 am 
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Greetings to the Forum:

What is not often understood is that early monochrome TV sets (the good ones where care was taken in engineering) ARE higher definition than later color sets.... but you also have to have vintage monochrome source material to take advantage of it.

Before compatible color, the video bandwidth was 4.5 MHz. Original source material from the period (this usually meant "live" material because recording techniques of the time were lower band width) was very sharp and clear.

When compatible color came along, the video bandwidth was reduced to 3.5 MHz. The color subcarrier was at 3.58 MHz. and the portion of the video bandwidth between 3.5 and 4.5 MHz. was reserved for two color signals in quadrature (R-Y and B-Y) to transmit the color information. Since our eyes can derive a lot of information about an image when it is in color, the luminance resolution was not missed.

There are some monochrome programs from the late 1950's and early 1960's that were recorded with full NTSC video bandwidth.... not sure how, perhaps using magnetic recording with the chroma channels disabled and the video filters removed.... but anyway, the detail is spectacular. I have seen a few of these and I am always struck by the resolution and sharpness of the picture.

So, you can go back to "hi-def" of the period..... just get a wide-band monochrome source for your video.

Regards,

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Thu 09, 2017 4:45 pm 
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I took the opening posters meaning of "Higher Definition" as it relates to the scan rate frequencies. It certainly would be much easier to modify the video frequency response if you bypass the rf and if amplifiers. In fact many of us have added direct composite video and audio inputs to old sets, which in most cases there's a notable improvement to both video and audio quality. If you do such an experiment you'll want to used the "Y"(Luminance) component output of your hi definition video source, which should eliminate the Chroma portion from color program material. If you use the complete color signal you'll often see what resembles a fine honeycomb or dot crawl pattern in the picture of a pre-color era black and white set.


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Fri 10, 2017 12:04 am 
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Kevin Kuehn wrote:
I took the opening posters meaning of "Higher Definition" as it relates to the scan rate frequencies. It certainly would be much easier to modify the video frequency response, especially if you bypass the rf and if amplifiers. In fact many of us have added direct composite video and audio inputs to an old set, which in most cases there's a notable improvement to both video and audio quality. If you do such an experiment you'll want to used the "Y"(luminance) component output of your hi definition video source, in order to eliminate Chroma dot crawl on a black and white picture.


Actually, there is no "chroma" on HDTV signals, since there's no subcarrier. When in analog form (which is not common), they are composed of three separate signals: Y (luminance); Pb (more or less equivalent to the B-Y portion of the NTSC chroma signal, but much higher bandwidth); and Pr (more or less equivalent to the R-Y, bandwidth equal to the Pb). In the OP's proposal, he'd just use the Y signal, of course.

I suspect that even if the original set's deflection amps could be coaxed into scanning at HD rates (720p might be possible), and the video amp tweaked for the necessary bandwidth, the spot size and phosphor granularity of the early CRTs would not be up to displaying all that was fed to it. None of the RF, IF and sound circuits (except the audio output) are going to be usable.

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Fri 10, 2017 2:41 am 
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Back in the day, 350 lines was considered high definition. It's all relative.

Bob

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Fri 10, 2017 2:10 pm 
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pixellany wrote:
I am devoting significant resources to help me get control of my persistent propensity to indulge in redundant verbosity while providing answers that go beyond and are perhaps even irrelevant to the original question.

The answer to your question?

No.

The above statement before the answer sure sounds like "NASA" :wink:

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Fri 10, 2017 9:13 pm 
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Jthorusen wrote:
There are some monochrome programs from the late 1950's and early 1960's that were recorded with full NTSC video bandwidth.... not sure how, perhaps using magnetic recording with the chroma channels disabled and the video filters removed.... but anyway, the detail is spectacular. I have seen a few of these and I am always struck by the resolution and sharpness of the picture.
Are any of these available today?

Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Sat 11, 2017 12:07 am 
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philsoldradios wrote:
Jthorusen wrote:
There are some monochrome programs from the late 1950's and early 1960's that were recorded with full NTSC video bandwidth.... not sure how, perhaps using magnetic recording with the chroma channels disabled and the video filters removed.... but anyway, the detail is spectacular. I have seen a few of these and I am always struck by the resolution and sharpness of the picture.
Are any of these available today?

Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html


Early quadruplex videotape machines, like the pioneering Ampex VR-1000 and the RCA TR-22, were monochrome only originally, and were color-adapted later. It was possible in later color quad VTRs to record & play back in mono only. Only a very few of those VTRs exist today, and fewer in working order.

Also, most networks took advantage of the erase feature and wiped the majority of early videotapes for reuse, since tape was initially fairly pricey. Early tapes deteriorated from wear and environmental effects too, so sadly we have few surviving videotape records from that period. I think there are some archives of those tapes (and maybe working playback units) at a couple of big museums. There was one in NYC I visited ten or so years ago that had a viewing room and a library of old TV shows.

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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Sat 11, 2017 3:59 pm 
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If you want to see full resolution B&W your best bet would be Blu-ray discs of things that were shot on B&W film like The Twilight Zone. Set your player to output 480i and use the Y output from the component jacks, or S-video. Newer players without analog outputs will need an adapter to convert to analog. It's important to use the Y output, not the composite video output since that will be bandwidth limited and have a chroma signal (even if it's a B&W disc).


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Nov Sat 11, 2017 6:16 pm 
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I receive my TV signal where I am from a Dish (no choice as only one over the air non HD CH & no cable here) which has some HD channels.

For some reason my older HD Motorola Sat. receiver is no longer comparable with what they are doing (I don't think it's fair & to top it off I have to buy their most expensive rec to get component video as it has a recording capability) & they are slowly changing all the HD channels to close to or DVD quality and they have done the movie channels first.
I wouldn't use the recording ability , so I guess if the HD is still the same as I computers I could take it out and use it for that and being very small now may be even laptop sized which I need!

Actually all the channels are now close to or DVD quality including the non HD ones! Before the non HD ones were terrible low definition! To get HD on my older HD TV's I have to use the component video as no HDMI. I noticed picture on my father's 50" Sanyo Plasma 720P TV is slightly brighter (looks nicer) hooked up with a component video cable over any HDMI cable!

Anyway to save my HD TV for movies I hooked up a regular def 12" Walmart Brand (it was a give away at a recycling place) with a regular picture tube (probably the last of the TV's they sold with a real picture tube) to the sat receiver and was surprised as it looks to be close to DVD quality also & maybe is.

It does have an RCA jack to plug in a DVD player etc!


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 Post subject: Re: "Higher" Definition on Antique TVs?
PostPosted: Dec Fri 15, 2017 6:33 pm 
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Even assuming you "could" modify an old analog set for HD (NOT) you would probably melt the Yoke, the Flyback, and probably a million other components with the higher scan rates. "Back in the day" there was some discussion of separating the vertical and horizontal circuitry at every point in the process, decoupling power supplies, shielding and the like, to beef up the analog resolution. I don't recall where that went actually but probably digital TV pushed it out of the equation. It seems to me that there was a process being developed that would significantly increase NTSC resolution as well, and it DID work, but that was quickly shoved aside as Digital became the heir apparent to higher resolution. "enhanced NTSC" if memory serves, which btw it seldom does.

Anyway, buy a nice flat screen and put it in the case where the CRT used to beeeee :-D


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