Salvage parts for analog TV set - Page 1
Forum section: electronics / repair

author: fixit7
author_rank: Regular Contributor
timestamp: May 24, 2019, 12:38:57 am
content: I found about a 25 inch analog TV by the dumpster.I thought about salvaging parts from it.I would need help discharging the large capacitor it has.It's so heavy, it would take 2 to carry it.Do you think it's worth the effort?

author: simxdx
author_rank: Newbie
timestamp: May 24, 2019, 12:45:37 am
content: Maybe it can be made into an oscilloscope.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 24, 2019, 01:54:16 am
content: put a 1k 5 watts resistor on the pins and wait a few seconds (10 secs ??)

author: fixit7
author_rank: Regular Contributor
timestamp: May 24, 2019, 02:00:28 am
content: I found out that Texas requires manufactures to dispose of TVs.I do not think enforcement is a priority.

author: xrunner
author_rank: Super Contributor
timestamp: May 24, 2019, 02:03:16 am
content: Quote from: fixit7 on May 24, 2019, 12:38:57 amMe?No.No, I do not.

author: vk6zgo
author_rank: Super Contributor
timestamp: May 24, 2019, 02:30:20 am
content: Quote from: fixit7 on May 24, 2019, 12:38:57 amI somehow doubt the large capacitor ( & which one would that be?) will still be charged, as it is unlikely it has been used for years.However, just in case,you can discharge them with a big screwdriver blade across the terminals.The idea of using a resistor is good, if you are concerned with maybe damaging the cap the other way, but, unless you can make a really solid job of the connections, you may (1) slip, & use yourself as the "discharge resistor, or (2) fail to discharge it at all.If by "large capacitor", you are thinking of the capacitance between the inner & outer coatings of the CRT, that doesn't have a very high capacitance, so can be easily discharged by the "screwdriver method".If it is an older 25" TV, it may be a good source of discreet power BJTs, or maybe even small signal ones.Later ones tend to be full of dedicated ICs & power modules.There is usually, a lot of useful hardware, like small metric screws, as well as self tappers in similar size ranges, star washers, plastic & metal clips & brackets, & so on.The wound components, like FBT, deflection yokes, possibly I.F transformers, & the various chokes from the SMPS may, or may not be useful.If nothing else, you gain an insight into how such things were put together.If you follow that up,by watching one of Dave's tear downs of test equipment from the same era, you will see the difference between professional & consumer standards of construction.

author: wilfred
author_rank: Super Contributor
timestamp: May 24, 2019, 02:40:01 am
content: What do you think you would use the parts for? I think if you repaired old TV's you wouldn't be asking the question.I'd say parts, no. But if the TV was somehow significant then someone with a specialist interest in them might have a different take.But since you're asking my answer is no.

author: fixit7
author_rank: Regular Contributor
timestamp: May 24, 2019, 03:08:40 am
content: If I took the TV which I will not, I am responsible for properly disposing of it.An average TV has about 5 lbs of lead in the glass.And I found no free recycle centers.As far as the large capacitor, I removed one using heavy gloves from a TV unused for at least 5 years.Got the crap shocked out of me.

author: shakalnokturn
author_rank: Super Contributor
timestamp: May 24, 2019, 08:44:28 am
content: I'd really like to see a photo of those capacitors that hold a nasty charge for >5 years, they could come in handy.You could always remove the rear cover, take the chassis PCB for the components and re-fit the cover, then arguably you're not responsible for disposing of the CRT, it was there before you've only recycled some of the e-waste. I used to do that quite often in my late teen-age when I fond a TV on the sidewalk that was to heavy to take as a whole.If you're into the odd repair or repurposing some of the components could be useful.I don't really believe any electronics equipment is recycled correctly, unless you're going to the trouble removing and reusing all those good components how can it be recycled correctly? Electronics is just such a mix of different materials that it isn't an economic option to recycle it. (In France we do pay a little extra tax on new equipment that is said to go towards EOL recycling.)

author: vk6zgo
author_rank: Super Contributor
timestamp: May 24, 2019, 09:29:14 am
content: Quote from: fixit7 on May 24, 2019, 03:08:40 amThe glass (which is the thing called a CRT) does not have "about 5lbs of lead in it".Yes,there is a small amount of lead in the glass to protect against the fairly unlikely emission of X-Rays.You have been reading misinformation from computer sites, where they commonly refer to the whole assembly as a "CRT".There may, or may not, be 5lbs of lead in the leaded solder holding the various components in place on the PCB & elsewhere, but the amount in the tube is not only quite small, it is locked up as a component of the glass, not loose inside.Many thousands of people, for decades, worked on TV sets, without needing "heavy gloves".If they really had occasion to change any of the "large capacitors" (which, for a solid State TV, are probably in the SMPS), they discharged them with a screwdriver "just to be on the safe side".Maybe your capacitor was a very good one, but most electrolytic capacitors do lose their charge over a long time.With large, oil filled Transmitting capacitors, "all bets are off".By the way, SMPS are often connected to the Mains in "standby" continuously.This will, in many cases leave the capacitors after the input rectifier charged.If a TV has been left "plugged into the Mains" and simply "not used", there is every possibility of the caps being charged.If it has been "unplugged" for that time, it is much more unlikely!

author: PKTKS
author_rank: Super Contributor
timestamp: May 24, 2019, 03:52:35 pm
content: If the unit predates the mixed SMT THT chassis it is worthyon a THT mostly board you have about a BAG OF BOTH HANDS FULLof resistors of very good quality, very good BJTs and diodes and some zenersand may be some power devices from the flyback mainsTransformers are far too much specific but the cores are usabletwo hands FULL OF USABLE THT PARTS ...i have done that quite some timesPaul

author: eevcandies
author_rank: Regular Contributor
timestamp: May 24, 2019, 09:45:37 pm
content: Maybe the TV set has a replay button--you can press it & re-watch all the shows it was tuned to.Actually, I bought an old printer from a flea market computer place & apparently it had been internally storing whatever had ever been printed on it...in case I wanted to print a copy!It was one of those big-box size laser printers.

author: tooki
author_rank: Super Contributor
timestamp: June 09, 2019, 03:41:10 am
content: Quote from: vk6zgo on May 24, 2019, 09:29:14 amSorry, but the OP is more correct than you. CRT glass is 22-28% lead by weight:https://cyberleninka.org/article/n/624141.pdfA 25” CRT won’t be 5lbs — more like 3 — but 5lbs was what might be found in the largest CRTs.

author: james_s
author_rank: Super Contributor
timestamp: June 09, 2019, 03:59:30 am
content: If it's in nice shape, CRT TVs are starting to increase in value as supplies dry up, particularly older ones in the 80s and prior. As far as parts, the CRT itself is the most valuable component, guys collecting vintage arcade games are starting to struggle to find replacement tubes.The "large capacitor" is the CRT itself. Generally it will discharge itself within a few minutes of the thing being shut off.

author: fixit7
author_rank: Regular Contributor
timestamp: June 09, 2019, 04:20:49 am
content: Quote from: james_s on June 09, 2019, 03:59:30 amThat TV set is still by the dumpster.If I can get someone to help me get it up my stairs, I will disassemble it.It's a 34 inch RCA.Andy