television components reuse  - Page 1
Forum section: electronics / projects

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: April 20, 2014, 10:54:04 pm
content: Have found that some tvs have power supply on separate boards and others are just one big motherboard. I'm wondering if it's possible for the all-in-one boards to pull off the power supply components and create a new power supply? Or am I dreaming?Also I have a few flyback xformers and wondering if there's any practical use for them?

author: janoc
author_rank: Super Contributor
timestamp: April 20, 2014, 11:34:24 pm
content: Depends on what TV you have.I wouldn't bother with anything that still has a CRT - those are usually directly connected to mains, there are nasty voltages inside and often the build quality of the thing is horrid in order to lower the costs to bare minimum (even in "decent" brand TVs).If you have a relatively modern plasma or LCD TV, you could try to separate out the PSU, but the question is whether it is worth the effort - you would likely need to reverse engineer and rebuild the PCB anyway, there are plenty of things you have likely little use for (high voltages for the CCFL backlight, for ex.) and the PSU is most likely built to work for a very narrow range of loads. Very often the components are various weird chips custom built for these applications that have little to no documentation publicly available as well.I would probably just salvage the components like the switching FETs/Darlingtons, optocouplers, transformers and diodes and toss the electrolytic capacitors and the rest of the carcass. Not worth the trouble, except as a learning exercise, IMO.

author: nanofrog
author_rank: Super Contributor
timestamp: April 21, 2014, 12:05:52 am
content: Assuming you're not on an absolute shoestring of a budget, I'd skip it. The parts used are cheap, and as mentioned, you'd need to make a board anyway, so a lot of effort for little financial value of the parts used.As per using any of the flyback transformers you find, a Jacob's Ladder or a Tesla coil are popular projects that use them.

author: vk6zgo
author_rank: Super Contributor
timestamp: April 21, 2014, 02:33:53 am
content: Quote from: janoc on April 20, 2014, 11:34:24 pmOf course they are directly connected to the mains-----they are switchmode power supplies."Transformerless" AC/DC supplies in TVs are a horror which was foisted on an earlier generation of Brits & Europeans,butthatdesign is very different to a SMPS.In any case, you are unlikely to find one of those outside a museum.The SMPS which are on the main board are isolated from the rest of the board,but it is still possible to zap yourself with an unwary finger.The separate ones are no more dangerous than a PC supply,except in the fact that they supply somewhat higher voltages.I wouldn't bother pulling bits off one of the main board types,as you will probably get fed up because it takes so long,try to hurry,& break a vital bit.The separate ones are a more viable proposition,used complete."Flyback "(Horizontal O/P) transformers?---yes,there are a few pointless projects you can use them in,but it's usually a lot harder than just making a 555 timer to drive them.They will hardly work at all at other than 15kHz,& they are designed to use a particular drive waveform.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: April 21, 2014, 03:00:20 am
content: Quote from: nanofrog on April 21, 2014, 12:05:52 amYes, I've seen these projects the jacob's ladder is fun to look at. I guess it could be practical in the right setting. Or maybe make it do double-duty somehow as a bug zapper too.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: April 21, 2014, 03:02:55 am
content: Quote from: vk6zgo on April 21, 2014, 02:33:53 amYes I'm not going to try to remake the PS. But I will look into using a 555 to drive a flyback.

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: April 21, 2014, 03:09:13 am
content: Quote from: janoc on April 20, 2014, 11:34:24 pmYep I will take the interesting parts, even caps for breadboarding. And almost doesn't matter what I do regarding electronics, because I will learn something since I know very little. Some parts I take off just to know what they are.I also came across a cap soldered onto a spot that specified a diode, that makes me curious. Intentional? If so what was the intent? So I ask myself questions as I go along. Most of the tube tv boards I've found are heavily silkscreened so it's a hands-on way to see what things are and I learn the symbology of electronics as well.

author: vk6zgo
author_rank: Super Contributor
timestamp: April 21, 2014, 04:14:08 am
content: Sometimes even major manufacturer stuff up their silkscreens.I have seen a Sony monitor with the polarity markings for some electrolytics reversed in the silkscreens on each side of a board.It couldn't have been too critical in that position,though,as thefactoryfitted them reversed compared to the circuit diagram,& the thing was 10 years old & still working!

author: GiskardReventlov
author_rank: Frequent Contributor
timestamp: April 21, 2014, 05:10:59 am
content: Quote from: vk6zgo on April 21, 2014, 04:14:08 amI believe everyone makes mistakes and consider it to be part of the entropic nature of being. No one and no thing's immune.I did notice several areas on this board where there were some visible signs of over heat.One heat sink had a considerable amount of browning radiating outward from where the soldered mount was screwed on to the heatsink and the tip of the screw was close to a resistor.I noticed inside the RF can that the shield covering the chip had brown heat signature.I noticed one cap on the board with a slight bulge.Also everything looked as if it had hair on it when I opened it up. The magnetized hair of the kind you see when you draw a magnet through iron shavings. Wires, really everything, I just looked at it all for several minutes a little bit astonished really. It was quite unique. Maybe due to the environment it was used in but possible it just had issues,I thought it may have been due to cigarette smoke but it seemed to be something else. Maybe picking up stray current via the coax connection? Or just bad house wiring.I think the tv brand was apex, absolutely ugly looking board. The through hole legs were all different lengths underside and top side they looked strewn about. Leaning over and strandling other components. The whole thing was probably destined to start a fire.