Yunost R603 soviet TV teardown and restoration 3 

reply where

What's going on here?

@@ngc253 general Kenobi

TVs evolved over time. The first sets had very small tubes. So over time as the TVs became more powerful I guess they could figure out what they needed to do in order to increase performance. It was an iterative process.

Like most things, it's merely a collection of smaller simple things.

@@1pcfred True, monochrome sets are very simple, as the standard put the most complex parts in the transmission side. Inverted video, so the noise would show up mostly as black and not peak white, and simple oscillators that were phase locked to the transmitter, and slow capture rate to make noise not show as jitter. Also sound on a defined subcarrier, so recovery was easier, and far enough away to both not get sound on vision with loud sound, and no vision on sound buzz with fast changing scenes. Well in the most part, but the early ones, with no ceramic filters or SAW filters, you always had a compromise, but it worked well enough, with just a single LC trap in the right places. Telefunken experimented with getting the tube count down, putting multiple stages, complete with the resistors and mica capacitors, into the same glass vacuum envelope, but they ran into issues with this, low pressure meant lots of arcing, and they were hard to manufacture. But they did make sets that were only 2 or 3 tubes total, with one doing the RF, IF and sound all in a single glass envelope, and the others doing the rest of the set. But they gave up, too expensive to manufacture, and too high a reject rate.

@@SeanBZA they say black and white is a sharper picture. I don't miss old CRTs. HD LCD is definitely an improvement.

@@godfreypoon5148 there's a lot of cleverness going on in those smaller things. That choke with magnets I'd have never come up with something like that.

Haha, you hacked DGW’s system.

How did he do it?

@@ozzymandius666 He explains it in the video - exploiting the aliasing phenomenon, armed with a 50 fps camera with very high shutter speed (1/16,000 s - that's faster than one scanline of the TV which takes 1/15,625 s) and with the knowledge that the 50 fps in the camera doesn't exactly match the 50 fps on the TV. What we see in the video is the slight difference in frequency between the camera and the TV, as in each frame the camera catches the electron beam of the TV in a slightly different position.

Niiiiiiceee

I know of a small German YT channel who commonly does so, too. Besides, I like to build them right in mid-air, just soldering the components together, without a board or anything.

Here 24GHz sine wave oscillator on a breadboard (his DMM tests like 15kV transients are even more interesting):: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-yR9TweWf3w8.html

@@stanimir4197 Yeah that's nice and all, but I basically consider everything above like 100 MHz being witchcraft. You know what I mean?

@@theschnilser7962 >above like 100 MHz So FM radio in Japan is all reasonable, but half of the international range is witchcraft? /s

@@theschnilser7962 no disagreement on the witchcraft part. Although Mr. Diode's version didn't reach 100MHz... so it's ok?

that one does look complex, looks all discrete, but many used ICs to reduce part count

Once I did not discharge the tube completely (there was arcing but I did not fully touch the terminal) and I can attest that it is a mule kick. My arm became numb for a few minutes.

or one turn inductance in resonance circuit )))

Its a logo of some capacitor factory

Agree.

В следствии деградации диэлектрика диэлектрическая проницаемость среды увеличивается, следовательно и ёмкость увеличивается.

Yes, usually the leaky capacitors will show much higher capacitance. I recently measured some from the 1960s and they showed 4uF instead of 0.25uF. I read on some forum that you can "heal" the leaky paper capacitors by boiling them in hot wax for an hour, but this was meant for caps that were in metal boxes that you could remove the innards and boil it, not the sealed ones like in this video.

Another quirk, the USSR actually produced paper in oil capacitors that were hermetically sealed. They are in ceramic tubes with metal ends. I have few of them and they are still 100% perfect with no leakage even at 1KV, despite rated at only 600V and have datecodes of 1964 and 1965.

I heard they burn out part of foil when electrical breakdown happens, and still work.

Bosna obecana zemlja

Except communism...

I'm sure that piece of sh..t does not support PAL/SECAM/NTSC )))

@@thisone1697 Some VHS players and old game consoles have an RF output.

I was always worried even about getting closer to powered-up CRTs exposed in an electronics repair shop I used to do some jobs at 15 years ago... I helped the older experienced guys into getting service manuals and stuff like that, but never ever touched those scary anode cables.

Yes, apparently they did. I have one here, an MDA model of some sort, I don't remember the number.

Right decision! Stay alive - don't touch that! )))

This gave me some ElectroBOOM vibes

It's not a high voltage TV, it's only 12v. Everything will be safe to touch inside except for some of the deflection circuitry. That happens to be exactly what he is touching, but I figure he knows it is safe. On most modern TVs the flyback primary is on the transistor collector, which is often connected to the heatsink. So if you touch one of those you could get a shock. I've been working on an _old_ TV which runs on around 400v. I'm a bit more careful playing around in that than I would be in a 12v unit.

@@eDoc2020 But for CRT to operate properly, you need several kilovolts on anode. Up to 25 kV if I correctly remember. Also high voltage on the other outputs of flyback transformer.

@@ShaLun42 True, but the real high voltage output is well identified and well insulated. Obviously touching random things in an unknown set is a bad idea but our host seems well-versed in this one's operation. Heck, the antique TV I'm working on runs at ~400v total B+ and I still poke around a bit in it when powered.

Skin resistance, with dry skin the charge built up on the glass slowly is discharged through your skin resistance, around 100k, with around 50pF charged to 10-25kV from the electron beam hitting the other side. Wet skin around 100R or less, so the same charge is now going to go through 1000 times faster, giving you a shock.

Yes, the max voltage falling is the main problem of capacitors that deteriorated this way. It is easier for them to arc over and become shorted.