How I Used Old TVs as Monitors

Rice. 1. My first video card.
Rice. 2. Connectors on the video card.

Two signals come out of the S-Video connector: a luminance signal (Y) and a color signal (C). Sync pulses are also transmitted in the luminance signal. The color signal is encoded in one or another color system (PAL, SECAM or NTSC, depending on the settings of the video card) and is transmitted on a subcarrier frequency. In order to connect such a source to a regular TV video input (tulip connector), you need to make a simple cord with a capacitor (classic diagram, Fig. 3). In this case, the chrominance signal is mixed through the capacitor with the main luminance signal, and such a signal is already a composite PCTS (complete color TV signal).

Rice. 3. Schematic of the S-Video–CVBS cord.

I was already informed in advance that it is not necessary to connect according to this scheme. It is possible to configure the video card so that the PTsTS is immediately transmitted by the brightness signal. When outputting a signal from a computer to a TV, of course, the quality in terms of picture sharpness drops noticeably. However, if you set the video card to the S-Video output and remove the mixing of the color signal (remove the capacitor in Fig. 3), then, obviously, the picture on the TV will become black and white. But at the same time, the image quality increases markedly: image ripples are removed. This ripple is caused by the chrominance subcarrier signal. If there is no chrominance signal in the video signal, then there will be no such crosstalk in the form of ripples either.

Shortly after graduation, I moved with this computer to another city, where I studied at the university. At the same time, I also wanted to have a computer at home when I come, for example, for the weekend. With my scholarship, I bought used components of an older computer: PSU, motherboard, RAM bar, video card (similar, but 32 MB), Celeron 1.8 GHz processor, HDD. At that time, I had not yet acquired a case, I found it a little later. Thus, I built a second PC for the house.

As for the monitor, it was not very easy then. Even a CRT monitor was then still in price. As you might guess, I used a TV as a monitor. At my personal disposal, since childhood, there were several old TVs. Among them was a color 3USCT, a black-and-white lamp and a black-and-white microcircuit-transistor. It was my hobby since childhood, I was engaged in TV repair.

A DVD player was connected to the 3USCT TV to the color module via the interface board via the RGB SCART connector. Knowing the configuration of the PC monitor interface, at that time I was thinking about connecting a video card to a TV via SCART. However, the hands have not yet reached this, and have not reached at all. With this connection, the crosstalk that I wrote about above, of course, is absent. At the same time, a high-quality color image is preserved. A connected DVD player is an example. I tried to connect it through the usual “tulip” of the PCTS to the 3USCT TV color module, using the same interface board. The difference in image quality is obvious to the naked eye. But if the DVD player is connected to the TV via the PCTS output, then it is possible to increase the saturation of the image, making it more colorful, which is impossible when connected via RGB.

Rice. 4. TV 3USCT – Rear view.
Rice. 5. Interface board with SCART connector.
Rice. 6. DVD player via RGB on 3USCT.

But most of all, black and white TV pleases my eye. In both TVs, I once made video and audio inputs and TV / AV switches a long time ago. In an older tube TV, I even made more exits (Fig. 7, side of the TV). Through them, I used to connect a VCR. Using the RF output on the VCR didn’t really appeal to me. Yes, and in the case of a tube TV, devoid of the UHF range, a special UHF set-top box was required (I had a VCR with a UHF RF output, although there are also MV ones). And when the DVD player came along, I was able to connect it to a black and white TV using only the luminance signal. This removes ripples from the image, improving its quality. The brightness signal from the DVD player can be taken from both the S-Video connector and the component output. The component output is three tulips, from which three signals come out: a luminance signal (+ sync pulses) and two color difference signals. I had a full-fledged player in terms of the number of audio and video interfaces. I want to note that through a self-made video input, the image was not always contrasting (depending on the video source). And if I connected through a VCR that was used as an RF modulator, then the contrast was higher, but there was a little noise in the image. To supply the TV with a full-fledged video input, you need to design a special circuit that will match the input with the source.

Rice. 7. DVD player connected to a tube B/W TV via the Y output.
Rice. 8. DVD player connected to m.-tr. b/w TV via output Y.
Rice. 9. DIY audio / video input and switch on the back of the TV.

So, for my second computer, I used a black and white TV (which is not a tube) as a monitor for about two years, until I found a normal CRT monitor. In order not to spoil my eyesight, I was two meters away from the TV. At the same time, while working on a computer, I used the standard Magnifier program to enlarge the image area around the mouse cursor (Fig. 11). The screen resolution is 1024 by 768. By the way, the eyes got tired of the black-and-white image much less than from the color one.

Rice. 10. A computer connected to a tube b/w TV.
Rice. 11. Computer connected to m.-tr. b/w TV.

A few years later, I got a new black-and-white kinescope compatible with the TV in fig. 11, and immediately changed it. After the replacement, the contrast increased many times over. Apparently, the old kinescope was dead. Just in the video, which was mentioned at the beginning of this article, a TV with a new kinescope was demonstrated. Screen resolution – 800 by 600 (freeze frame in Fig. 12).

Rice. 11. Computer connected to m.-tr. b/w TV with a new kinescope.

Currently, the phrase “connecting a computer to a TV” means, as a rule, connecting to a modern flat-panel TV via an HDMI connector. Or maybe even connect to a smart TV via Wi-Fi. At that time, I could not even imagine such a thing, just as representatives of the current generation will not be able to imagine everything that is written in this article.

Similar Posts

Leave a Reply Cancel reply