![]() ![]() ![]() CRT TV sets are now a long-gone anachronism, so for a younger generation there is very little chance to see them up close and thus watching one built has some value. Perhaps merely assembling a kit might not seem the most exciting subject for a Hackaday story, but this one is a little different here in 2022. The scanned area doesn’t fill the screen and he doesn’t find the solution in the video, we hope that by his next video someone will have suggested moving the deflection yoke forwards. Satisfyingly it works on first power-up, though some adjustment and the reversing of a deflection yoke connection is required for a stable picture. The unboxing and building proceeds as you might expect, with the addition of very poor documentation and extremely low-quality parts. It’s an exceptionally cheap set of the type that was available from discount stores for a laughably low price around the final few years of mainstream analogue TV broadcasting, and having a couple in the stable we can confirm that the value here lies in building the thing rather than owning it. We have to admit to having seen the same kit and despite a sincere love for analogue telly, to have balked at the price. Perhaps that should be amended to almost nobody, because has assembled a small black-and-white CRT TV from a kit he found on AliExpress. With a burgeoning consumer electronics industry the price of a new TV quickly dropped to the point of affordability so nobody would consider building one themselves today. Thus it wasn’t uncommon at all for electronics enthusiasts of the day to build their own TV set, and magazines would publish designs to enable them. It is a Mitsubishi CS-20101.There was a time following the Second World War when TV sets for the nascent broadcast medium were still very expensive, but there was an ample supply of war-surplus electronic parts including ex-radar CRTs. I have looked for the schematic but could not find it. I can run it for a while then hit the cap with the freeze-it and see what happens. I suspected the warmed up caps would work better which is why it has no trouble turning on once it has been running for a while. I wasn't quite sure what the freeze-it was supposed to do. What make and model? I can probably point you strait to the bad cap(s), though if you're not in the USA I might have a hard time getting the schematic. Heating the cap(s) that are going bad will relieve the problem. As it warms up, the electrolyte expands and begins to cover more and more plate area - the space involved is very narrow, so a bit of heating will be able to re-wet a relatively large surface area.Ĭooling the cap(s) that are going bad will induce the problem. When the electrolyte is cold, it contracts and areas of the plates are not in contact with the electrolyte. Old 'dry' and overheated caps will be lacking in electrolyte. The capacitor is like that, in that is uses an electrolyte between plates that are rolled up like a rolled up newspaper. If the battery acid doesn't fully wet-out the plates there's reduced conduction area. A simple way of looking at it (physically) is a car battery. They (when going bad) will have their best values when they are warm, their worst values when cold. Still curious as to how this freeze-it affects the capacitor? What does cooling the capacitor do to it?Ī capacitor passes changes in voltage (AC) while blocking DC voltages.Īluminum electrolytic capacitors can go bad with age and heat. I had figured it was probably a capacitor problem to but was looking for a second opinion before I replaced any. Always take note of the polarity of the original cap and then cross reference with what's silk screened underneath. One thing to note, it's quite possible that the silk screening can be wrong on the underside for Positive lead placement. The cap rating in uF is the important part, the voltage rating can be slightly higher on the new cap, but never lower. While it's advisable to buy the correct and exactly matching caps that you could list as required, you can salvage them with quick desoldering from later other household items.perhaps even a newish TV with bust plastics, or a hi-fi. You'll likely find that horizontal hold, any image tearing and other mild problems also disappear when you replace the caps. I'd advise replacing any caps you can get to, even the 0.1uF 50V ones play important roles. 'Cap Kits' as they are commonly called are available for many monitors of the time and new caps will fix a multitude of similar problems. It's all too common in one of my hobbies, 80's arcade machines. Seems cap related, the clue is in the word 'old'Įlectrolytic caps dry out over time, faster when near to heat producing components with heatsinks on. ![]()
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