Being the Salvage Guy!! - Page 1
Forum section: electronics / beginners

author: xibalban
author_rank: Regular Contributor
timestamp: December 18, 2014, 06:11:29 am
content: Greetings fellas!!In about a fortnight, I shall be a proud owner of a Hakko 888 Analog & Uni-T UT139C among other ancillary tools. I'd then begin my role of a "salvage guy" and shall try to get hold of any 'useable' component that comes across. Why salvage old components, one may ask:Recycling electronics (or anything for that matter) is always good for the environmentI'd gain experience on soldering & desoldering in the processI'd learn how to test components and whether they can be re-usedI'd learn a lot about measurements and stuffs, and about using a multimeterI'd gain a better understanding of PCBs and electronics in generalMy concern is whether it is worth my time/energy to try and salvage components off a totally soaked PCB? Components found smeared in mud or the like. I was wondering if transistors, diodes, LEDs could still be useable after they're exposed to continuous moisture or oil, dwelling inside an outdoor dumpster for example.I'm sure that electrolytic capacitors would be ruined, but ceramic ones? And, resistors & inductors, ferrites, etc? Has anyone even tried finding out?I'm at a loss fellas, please advise.

author: nanofrog
author_rank: Super Contributor
timestamp: December 18, 2014, 06:34:54 am
content: Quote from: xibalban on December 18, 2014, 06:11:29 amGo for it. Not really all that cost effective for passives and most silicon parts as a general rule, but is a learning experience IMHO (particularly useful for desoldering/soldering).It is a good way to find power transformers, large coils, heatsinks, and larger enclosures on the cheap IME when you can find them.Quote from: xibalban on December 18, 2014, 06:11:29 amI'd skip stuff in this bad of shape (continuous exposure to moisture and such). Got a little rain on it, but not soaked, may have spared the PCB's.

author: rob77
author_rank: Super Contributor
timestamp: December 18, 2014, 08:01:14 am
content: nothing wrong with salvaging components, even resistorsi would definitely skip the boards which were permanently soaked or were in mud, but a board exposed to weather for some days and still without corrosion might be ok (just clean it and let it dry).

author: Seekonk
author_rank: Super Contributor
timestamp: December 18, 2014, 08:02:46 am
content: I'm a fan of the grinder with a thin cutoff wheel. A lot of electronics is organized on a board in usable sub assemblies. A surface mount power FET is best left intact and circuit board will often give an isolated mounting to a cabinet. I visited a small producer that used a home dishwasher to clean boards. Most components can tolerate water for a while but solderability will become an issue.

author: atferrari
author_rank: Frequent Contributor
timestamp: December 18, 2014, 10:15:45 am
content: Quote from: wilfred on December 18, 2014, 06:57:32 amYes to many of the above.As an incipient ham, I started collecting parts to build my first xmtr, disassemblingcompletelymany pieces of equipment with tubes (valves). Learnt the hell of tricks for assembling and got hundreds of parts. I can say than along the last 20 years I progressively binned them feeling bad because my hard work proved basically useless. I am not sure if I ever used other than one or two resistors.Changing to transistors / ICs was the main cause.Some time later, I got on board (I was young Ch. Officer) a Loran C receiver that could not be repaired in time and so discarded. Full of logic ICs, it came home with me. Have to recognize that I was clever enough to not to disassemble anything. I have already discarded some of those boards.Now, I do not desolder anything that I do not need at the moment... but and this an important BUT: if intact and useable, put apart any power supply (printers have some which are very good) that could be "inserted" in a new design.Long time ago, I started to evaluate all this considering the time I spend and how much yarn is left in my personal bobbin. And the actual usefulness of doing that. Almost zero.One eventual "exception". An Epson printer, which after reverse engineering had the micro inside exchanged after brain surgery. A new micro was able to activate the whole thing and steppers did what I wanted them to do. The printer was intact when I started.The trick (works for me) from time to time, I do a very quick check of the boards in storage to refresh my memory record of special items available. Probable more with hardware that silicon in mind.Sad to say, I became more and more skeptic about all this because it involves a previous workload that eventually could mean saving the buying of one or two things. (Contradictory, 1/3 of my space used in this hobby is occupied by discarded equipment collected at many places). But...that's me.In other (few) words: disassembling in advance:don't. Keeping: yes.

author: xibalban
author_rank: Regular Contributor
timestamp: December 18, 2014, 03:35:14 pm
content: Quote from: atferrari on December 18, 2014, 10:15:45 amQuite a detailed response that was, thank you.What do I do with broken PCBs? If I were in need of a certain component, do I just salvage it when required? Or, get with the component desoldering, testing and sorting on-demand basis? And, say that I didn't desolder the components before-hand, how am I to store them after carefully sorting them into component boxes based on their type and value.You see, all that I intend to do is recycle i.e. to reuse these components that I'll have found to be good, in my upcoming projects like an AM receiver, etc. The idea was to have different boxes for each component value like - a box of only 100 ohm ¼ W resistor, a different box filled with only 4.7 kilo-ohm ¼ W resistor, etc and similarly for capacitors, diodes, etc.Is there a standard cleaning agent I must be aware of (like ethyl alcohol), for cleaning the PCB (and components) after careful drying?

author: jeroen79
author_rank: Frequent Contributor
timestamp: December 18, 2014, 04:38:38 pm
content: I would make a point of detailed bookkeeping.When you 'process' a device you write down what interesting parts it contains with all relevant details.You then save this in a format that is easy to search. (excel table, database, well structured text files)Then when you need something you can search your records and find out from which device you can salvage it.Also look for service manuals and schematics on the internet.These will have information about what is in a device.

author: atferrari
author_rank: Frequent Contributor
timestamp: December 18, 2014, 06:39:56 pm
content: Any kind of inventory, seems to me like choosing the tree where you want to hang yourself. Kind of a self inflicted slavery with few and brief moments of glory.I attempted it thrice; the first was an inventory of all articles of interest in the hundreds of magazines I bought for years (somewhat useful). The inventories (hardware) just a waste of time.Sorry. I am not being negative but sincere.

author: nanofrog
author_rank: Super Contributor
timestamp: December 18, 2014, 08:22:44 pm
content: Quote from: xibalban on December 18, 2014, 03:35:14 pmStore the entire salvage board in a box, and pull parts as needed.Quote from: xibalban on December 18, 2014, 03:35:14 pmNow about a box that says "Transformers" (non-PCB mount types), another that says "PSU's" and so on for entire boards?Quote from: xibalban on December 18, 2014, 03:35:14 pmIsopropyl alcohol, ethyl alcohol, methyl alcohol, or denatured alcohol will do (not sure which is most available to you, and cheap). Do try and get a high % (say 95%+ alcohol), and watch out for additives.

author: xibalban
author_rank: Regular Contributor
timestamp: December 24, 2014, 10:41:15 am
content: Hi fellas,Guess what, I've heeded your advice and have refrained from removing components off the PCBs that I've collected (quite a good collection already).I've come across this multi-tap transformer from a voltage stablizer (best guess) with no labels whatsoever; have a look:Now, how do I ascertain the following:The power rating, since there are no labels anywhere?The primary winding terminals? (my guess is, the terminal pairs with the least resistance must be the primary; assuming that this must be a step-up transformer)The common secondary terminal, if any?Could someone provide some pointers please!

author: rob77
author_rank: Super Contributor
timestamp: December 24, 2014, 11:22:35 am
content: Quote from: xibalban on December 24, 2014, 10:41:15 amfirst of all, please do NOT connect that rusty transformer to mains !regarding the powerrating - it's safe to compare the size and weight of a transformer to another known transformer. any two transformers with a same power ratings and same core style (EI,C,toroid) will have very similar sizes and weight.if it's step-down transformer supposed to be connected to mains , then the highest resistance winding is the primary.to figure out the rest of the windings - measure the resistance between the secondary terminals and solve the puzzleanother method would be to connect a AC CURRENT LIMITED LOW VOLTRAGE (12V AC max!! , preferably less) to the winding with the highest resistance and measure the AC voltages on the other windings... this way you will know the ratios as well. for current limiting - use a light bulb in series with the transformer when connecting the AC LOW VOLTAGE to the winding with HIGHEST resistance.

author: xibalban
author_rank: Regular Contributor
timestamp: December 24, 2014, 11:35:28 am
content: Quote from: rob77 on December 24, 2014, 11:22:35 am

author: rob77
author_rank: Super Contributor
timestamp: December 24, 2014, 12:00:21 pm
content: Quote from: xibalban on December 24, 2014, 11:35:28 amyou don't have to buy itjust have a look at the power rating and the size of a transformer in the store

author: xibalban
author_rank: Regular Contributor
timestamp: December 24, 2014, 01:41:16 pm
content: Quote from: rob77 on December 24, 2014, 12:00:21 pmSadly, I can't just walk into a store and compare because no such store exists in my town. Even for a 10 ohm resistor, I'd have to hunt it online. Salvaging components makes so much sense to me, if you know what I mean.Aren't there certain tests that I could perform on the transformer to ascertain its rated power?

author: dannyf
author_rank: Super Contributor
timestamp: December 24, 2014, 01:43:52 pm
content: QuoteNobody knows how you value your time / energy so that's an impossible question to answer.Quotesemiconductors are typically hermetically sealed so shouldn't be a problem.

author: xibalban
author_rank: Regular Contributor
timestamp: December 24, 2014, 01:56:18 pm
content: Quote from: dannyf on December 24, 2014, 01:43:52 pmWell, I implied whether or not I would end up with a useable component after all the time and energy that I'd use to salvage it. And time, oh I don't mind expending some.So you're saying that semi-conductors, if I understood correctly, may be useable even after exposure to rain or moisture. Right?

author: SeanB
author_rank: Super Contributor
timestamp: December 24, 2014, 02:02:44 pm
content: Transformer that age and size I would put at around 80-100VA, and from the construction I would guess it was to power some valve equipment, so will have a primary with 2 coils of 0V, 90V, 100V, 105V, 110V, 115V and120V, which are either run in series or parallel to allow it to operate from 90, 100, 105, 110, 115, 120, 180, 190, 200, 205, 210, 220, 230, or 240VAC mains ( valves needing a tightly regulated heater voltage and anode voltage), with likely secondaries being a 6.3VAC 5A winding, a 300, 0,300VAC winding, a heater winding of 6.3VAC for the HT side ( insulated to 600VAC for safety) and possibly a 75-100VAC winding for bias supplies.At the probable age, and seeing as the insulation is paper only, using it would be hazardous. I would suggest taking it apart to see how it is made, and the insulation used. Then at the end you will have 1kg of scrap copper and about 2kg of scrap iron. Inside you will probably find purple insulated wire and other colours, which are not common these days, as the insulating varnish then came in a few colours,, while modern ones are mostly light yellow or clear.As to stuff in water and rain, you might find they will work once dried and after cleaning ( water wash for mud, oil and such you might want to use soap first then rinse with water) and then test and use those without bad corrosion. However anything with paper insulation ( capacitors with paper coverings, transformers and such) might take months to dry out, even if kept at elevated temperature like in a warming drawer for weeks. Electrolytic capacitors that have sat in oil will likely have the rubber bung gone soft, so if it is soft scrap it, otherwise use it. It will have limited life left in any case.

author: jeroen79
author_rank: Frequent Contributor
timestamp: December 24, 2014, 02:04:05 pm
content: Quote from: xibalban on December 24, 2014, 01:41:16 pmYou can still look up specs on a webstore (the better ones will have detailed specs and datasheets) and compare them to what you have.QuoteA first estimate can be made based on size, weight, voltageratios and wirethickness.After that you can test it by drawing a bit of power through the transformer while measuring how hot it gets and what voltages come out of it.Then step up the power until it gets too hot or the voltages drop too much.

author: rob77
author_rank: Super Contributor
timestamp: December 24, 2014, 03:46:07 pm
content: Quote from: xibalban on December 24, 2014, 01:41:16 pmyou can calculate the max current from the diameter of the wires (and measure the voltages and calculate the ratios as suggested before), once you have the voltages and max current -> you can calculate the approximate power-rating. once you have it, you can verify it by a practical test - connect the transformer and load it... if it doesn't overheat, then your calculations are ok

author: xibalban
author_rank: Regular Contributor
timestamp: December 24, 2014, 03:54:43 pm
content: Overheat?What value in Celsius could be qualified to be termed an "overheat"? Also, for how long in minutes do I load the transformer before I grab a temperature probe. Thanks