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Salvaging used components - Good idea?

Discussion in 'General Electronics Chat' started by Ratchit, Jan 11, 2015.

  1. Ratchit

    Ratchit Well-Known Member

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    To the Ineffable All,

    I used to salvage parts from circuit boards like that, but one usually winds up with resistors and caps with short leads that are mostly useless for a lot of applications. Yes, I know there are ways of extending the leads, but is it practical for the time spent to do it? I don't think so. So now I just buy every component that has a lead in a unused condition and cut the lead of a component to comply with my application.

    Ratch
     
  2. jpanhalt

    jpanhalt Well-Known Member Most Helpful Member

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    IMHO, the most valuable components are the mechanical things, like switches, connectors, and hardware. Resistors and capacitors are a waste of time. Big inductors, like from SMPS, are valuable, if you know what they are. IC's are probably irrelevant. If they are labeled, MCU's are protected and cheap. Other logic chips are also cheap. If they have proprietary labels, forget it. There may be some rare IC's with value. But it is certainly not worth the time to remove most of the IC's, identify them, label them, and catalog.

    John
     
    • Agree Agree x 1
  3. gary350

    gary350 Well-Known Member

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    The high price easy to get parts are the best to salvage. I get certain power resistors, large capacitors, mosfets, voltage regulators, heat sinks, transformers, chokes, 1/2 watt resistors if they are easy to get, certain 1/4 watt resistors if they are very easy to get and certain connecting wires. If I can read the numbers and find ICs I can use I will some times get them, I found several NE5532 nice op amp ICs yesteday.

    It is Road Mart week in our neighbor hood. The guy across the street and a guy 2 blocks over both threw out a large flat screen TV. I know there is $50 worth of power resistors in those TVs. That 52" x36" plexaglass screen is worth $10 a sq foot. There is a large power transformer that will sell for $40 on ebay. Lots of other good parts but today I dont want them.
     
    Last edited: Jan 11, 2015
  4. dave

    Dave New Member

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  5. tunedwolf

    tunedwolf Well-Known Member

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    I would have to say that I find there is very little nowadays actually worth the effort. Between possible thermal, esd damage or at least shortened life, reusing salvaged semiconductors is a risk. Cheap proprietory high frequency transformers from the far east are simply not worth the time. Also, the replacement costs are so small now, there's little return. About the only time I will salvage a board is when I have multiples of them for repair and original parts are scarce. In those cases, it's sometimes better for one board to just take one for the team, other than that, I have better things to do with my time :)
     
  6. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    Are you sure about that? - TV's have all been switch-mode for decades.
     
  7. MrAl

    MrAl Well-Known Member Most Helpful Member

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    Hi,

    Yes some components are worth salvaging and some are just a waste of time. In general, the larger the part the more valuable it is, or maybe you would like to go by weight.
    Power resistors and line transformers are a pretty good catch, but i'd be careful about electrolytic caps as we all know they dont last as long as we would like. The worst thing to do is pull a bad part and try to use it for something. Potentiometers could be good or very much used already.
    Maybe we could make a list of the "good stuff" to look for :)
     
  8. MikeMl

    MikeMl Well-Known Member Most Helpful Member

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    Another point:

    I still build stuff from scratch. I would much rather build one-of circuits using through-hole parts, especially DIP ICs, instead of SMDs. The availability of through-hole ICs has, even for common things, begun to dry up. I reclaim used through-hole DIPs rather than have to screw with the little adapters so that I could use an SMD part.
     
  9. atferrari

    atferrari Well-Known Member

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    No matter how many parts you salvage, it is not simple to remember what is in the drawers. You need an inventory but you risk to become a slave of it. Nothing I like.

    Stupid excercise as it could seem, just opening boxes and drawers from time to time, helps to refresh the list in your mind.

    If you do not remember it, you do not have it.

    One thing I always try to save are power supplies.
     
    Last edited: Feb 20, 2015
    • Like Like x 1
  10. cowboybob

    cowboybob Well-Known Member Most Helpful Member

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    Small, plugged intra-PCB connectors (M & F, whatever wire count) are my favorites.

    Tossed DVD, VCR players and small CRT TVs (even the occasional microwave oven) are good sources. They make my homebrews look considerably less homebrew-y.

    Rarely salvage any other components.
     
  11. Misterbenn

    Misterbenn Active Member

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    I always salvage mains plugs as they are stupidly expensive from local hardware shops.
    Also motors, gears and other mechanical power transmission components. These are often easy to remove and quite expensive to buy.
    I'm a development engineer so I get most of my other small components from the lab stores, or sometimes i'll get entire circuits from ex-test PCBs they've usually been treated quite roughly but I've all the data on the design so I know exactly what its capable of and how to fix it.
     
  12. gary350

    gary350 Well-Known Member

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    YES those large screen TVs on 4 wheels that weight about 500 lbs and are 4 to 5 feet wide have a 1200 watt power transformer just like the old TVs of the 1960s. I carry tools with me all the time, when I see a TV it takes me about 45 seconds to remove the back and about 60 seconds to unplug the wires and remove the screws that hold it in. Some of those TVs have GLASS lenses I love to have those for reading number on parts and the color code stripes on 1/4 watt resistors. The plexaglass front is worth $10 per sq ft it cost $20 a sq ft at Home Depot or the hardware store =$50 on ebay or craiglist. IF the fresnel lens behind the plexaglass is a circle type design NOT the straight line design it is worth $150 on ebay. Hold the fresnel lens in the sun it is a giant magnifing glass. I use one to burn out tree stumps, every day the sun makes a 1" diameter 5000 degree laser spot pass through the tree stump. Move the lens over 1" every day and a month later the stump is gone.

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  13. tunedwolf

    tunedwolf Well-Known Member

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    Burning out tree stumps is novel use for a salvaged fresnel lens I'll admit, however, in dry climates, use it with caution, it's easy to set a root system on fire and if they run under the house...well it's time to pack up the budgie :D

    One thing I did salvage a lot of was old desktop scanners, I used to convert them into PCB exposure units for friends :)
     
  14. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    You mean old projection TV's? - they never weighed 500 lbs, nor had 1200W transformers in them - and any mains transformers at all must be out of incredibly old sets (probably the 60's as you mentioned).

    I', also a bit dubious what use such a transformer might be?, totally useless voltages presumably?.
     
  15. gary350

    gary350 Well-Known Member

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    You should NEVER say NEVER. TVs don't all have power transformers but some do. At first look you may not see the transformer, often it is hidden behind the 6" thick wooden wall. If you see a bundle of wire going behind the wall there is probably a transformer back there. The partical board wall is strong it often takes a whole hour to remove it.

    I was not planning to salvage anymore TVs but this one was setting across the street so I pushed it over to my house just to prove a point. I would RATE this TV very low on the list of good salvage parts. The circuit board at the end of each picture tube is small but it is often loaded with several $$ worth of power resistors. As you can see in the photo this TV has few power resistors. The only thing of good value on this TV was the power transformer. There are several good power resistors on the other boards. Lots of large capacitors that I don't need more of. Each TV is totally different, this one has rows of heat sinks with either, mosfets, power transistors, or voltage regulators on them. I will check some of the part numbers before I waste my time. The 4 caster wheels on the bottom of the cabinet are worth $10.

    The plexaglass screen is worth $50 cash on craigslist to anyone that needs replacement windows that are not glass. Lots of people like to cover their brand new desk with plexaglass to keep it looking nice. It also makes a good pad for the carpet to put your computer chair on so it rolls around easy and looks nice too. This fresnel lens is worthless, wrong kind.

    You need to be selective about the neighbor hoods you pick in. Low rent neighbor hoods, they trash is worthless trash. The people that are well to do often throw away good stuff just because they want a newer one. About 80% of the microwave ovens I pick up, Work.

    I picked up 118 bicycles one year but I got tired of bikes they take up lots of space and take lots of repair to make them work, sometimes it takes 3 bikes to make 1 good working bike. With Wal Mart selling bikes for $35 to $85 each bikes are worth more as parts. The 3 speed pedal cranks will sell for $50 each on ebay. Derailleurs are worth $20 on ebay. Aluminum wheels $25 on ebay. Shifters sold in sets front and back $20. Best way to make $$$$ with bikes is use the parts to build custom bikes. It takes me 3 days to build a Low Racer bike and they sell for $1500 each. Wind resistance is 65% less than an upright bike that makes it easy to pedal 32 mph. World speed records on a Low Racer bike is 81 mph.

    I bought several bargin packs of assorted resistors before Christmas, there are lots of values I still do not have. Yesterday I was working on a project and I did not have the correct resistor so I was forced to connect 3 resistors together to get the value I needed. I will check these circuit boards for easy to get resistors. I like the ceramic, gum drop and film caps too.

    This is ROAD MART week for our neighbor hood all the streets in a 5 mile circle are covered with things people don't want. I made $20K last year picking up other peoples trash. Most people have NO clue parts are worth more than the item. A junk microwave is worth $40 in parts. I picked up a dozen 6' step ladders last year sold them $50 each. Wife picked up 240 child car seats sold them $30 to $35 each. I picked up about 15 stainless steel sinks got $60 to $80 each. I picked up about 40 used toilets sold them all $25 each. There is a ROAD MART week in every neighbor hood we go to all the ones close to use every Monday morning before the dump trucks show up. This year we have decided not to do anymore ROAD MART and do more camping and traveling. The best part about Road Mart is, it is FUN and it gives retired folks something to do. You never know what treasure you will find around the next corner.

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    Last edited: Jan 12, 2015
  16. dr pepper

    dr pepper Well-Known Member Most Helpful Member

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    When I'm not busy I have a stack of boards and I recover bits of them, it does save buying new ones, I dont salvage resistors except bigger ones, and I dontbother with small caps, however big caps, power devices, ferrite transformers are all usefull, and working in a plant means I occaisionally get something hefty like a motor drive to pull to bits and get lots of usefull bits like huge heatsinks and hefty fets/igbt's.
    I dont mind soldering longer leads onto things to get something working, its better than waiting or trailing across town to pick something up, esp for a prototype.

    I learned a bit about switching power supplies by salvaging ferrite cores.
     
  17. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    So you claim that pretty light TV pictured actually weighs 500lbs :D

    Nor do they have 1200W transformers in them.

    As a TV service engineer for over years I've carried plenty of them - FAR lighter than much smaller CRT sets.

    It's not something you see too much of in Europe though, the poor picture quality and abysmal viewing angles from them meant people weren't very interested.

    Nor do they have 6" thick wooden 'walls' :D

    Perhaps you should learn not to exaggerate everything you claim - it makes you look rather silly :p

    Obviously what you can sell something for is dependent on what idiots will pay for junk, but of what use is the mains transformer in the picture you posted? - presumably it's got useless winding voltages?, so not much use?.
     
  18. gary350

    gary350 Well-Known Member

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    You sure are a net picker for details. I have never put one of these TVs on scales, SO WHAT if they dont weigh exactly 500 lbs. I can not pick one up I dont want to hurt my back. Wonder why they have wheels if they are so light weight and easy to move.

    Just because you have never seen a transformer of these TVs does not mean some companies do not build TVs with transformers.

    Yes some TVs have what I am calling a double wall. They make the cabinet that everyone sees on the outside. There is a boxed in the inside cabnet I assume to hide or protect the speakers and the transformer. That is what i am calling the 6" double wall just a boxed in place in both corners.

    Voltages are easy to determine on those transformers. I ohm it out first and mark the windings. Then I put 6 volts AC as test voltage on the other windings. 2 black wires are useually 120 vac. Once I determine the 120 vac I connect 120 to it and test all the other windings. Once they are texted and marked the windings they sell easy on ebay. People want to know what they are buying. Lots of people TRYING to selling unknown transformers on ebay with not much luck.
     
    Last edited: Jan 12, 2015
  19. debe

    debe Active Member

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    I salvaged a couple of transformers from an old 70s 4KA Thorn 26" colour TV. They were imported from England as live chasis, but here in Australia the importers had to fit a 240v to 240v 120Watt mains isolating transformer. I now use them as isolating transformers for working on SMPS.
     
  20. gary350

    gary350 Well-Known Member

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    Pick of the day. This TV turned out better than expected lots of parts all squeezed into a very compact space. I had to remove things i did not really want just to get the things I did want. Lots of good parts, I like that purple heat sink, about 40 mosfets and 78xx series voltage reguators 5 to 12 volts, lots of power resistors, some small useful transformers, chokes, LED power on light, lots of good caps of all varieties, lots of resistors that I need. Pretty good for about 2 hours of FUN. This is recreation to me.

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    Last edited: Jan 12, 2015
  21. atferrari

    atferrari Well-Known Member

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    Hola Gary,

    Please tell briefly how you take them apart. They look more or less intact.
     

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