A technique I still find useful if you have an air compressor is to blast the solder off a heated component pin or wire. I just heat the pin with a soldering iron, holding the air gun tip almost touching. When the solder melts, a quick blast from the air gun blows the solder clean off, usually including solder in the through-plated hole. The splattered solder is not a problem as it falls off the board or other components quite easily with a little prodding. This also works with bent-over leads which can be straightened for removal once the solder is gone.
I work here in Australia in a large research lab so I scrounge a lot of cast-off electronic gear. The most recent addition was a late-1980's electron beam machine used for e-beam lithography. This had a complete set of spare PCBs and power supplies that had never been removed from their boxes. The storemen now give me a call when anything electronic is being thrown out.
@BK11 - I have tried that and it does work. However it's best with Surface Mount - you just shake the board and off they come! With thru hole the solder resolidifies before you have all the chips off, and you have to wear thick gloves to handle the board, and you need patience - the boards take a good time to heat up. Clever using it for reflow though - theremostat control and all......
I've read about several people that use an old toaster oven as a reflow oven for DIY SMT work. It seems to me that it could also be used to strip SM & TH boards by heating them up just enough to melt the solder without destroying the components or burning the PCB.
For a while, in the days when memory was DIP and expensive, I did a sideline business stripping memory chips from PCBs, cleaning and testing them, and selling them. When I got scrap memory boards, they were multilayer with 50, 60, 100 chips on them. Even a heat gun was too slow to remove that many. I used a gas grill and a screwdriver. You could easily tell when the solder was melting and just run the screwdriver down the middle of the row and you could strip a board in a matter of 5 minutes. Of course, you'd lose a few into the grill, but it was quick labor.
@Hyman1 (and Zeeglen) - I did get some tube gear - there was lots of it around in the second-hand shops when I was a kid - but I think I came in just at the end of that era. I never built any valve gear, though I did later get and refurbish a couple of GEC 912 10W amplifiers. I sold them when I left Zimbabwe - now one of my regrets, though they weigh a ton and would cost heaps in excess baggage charges to get to Aussie!
I started out at the age of 6 or 8 when I ruined my father's record player. Besides making me pay for the damage, he also gave me an old radio to tinker with. That's where my first parts came from - stripped not from PCBs, because the radio was too old to have any PCBs: A metal chassis, some tube sockets and other solder joints. Leads were long, so I could even cut parts out rather than solder (didn't have a soldering iron in these early days of my electronics obsession).
Later I got some electronics kits, and I also started to repair (instead of destroy) TV sets that others didn't want any more. Earned my first money reselling them after repair. And of course mostly used parts from other TV sets went into those repairs...
I had a friend whose father worked at IBM. Sometimes we got computer boards with lots of resistors and other strange parts, which we stripped.
I still have lots of parts from these days (now 30 years in the past) in my home lab. Sometimes I still use some of them, but where I work I also have access to a lab stock of new parts whenever I need some standard part I don't have. We have an official policy that taking parts for home-lab projects is OK. They book it on the education account ;-)
I think quite a number of technical careers start that way...
Nice article, David. My Dad was in the RCAF (Royal Canadian Air Force) and would bring home one-shot telemetry equipment from drone target practice. Point-to-point wiring and miniature soldered-in vacuum tubes, got many resistors and capacitors out of these.
Ahhh, the good old days when an aspiring kid could take a junked TV set and rework the power transformer and horizontal output tube into a 50 watt ham radio transmitter...
Hi Javi. I know there are people in India who do this, I have heard of them getting very sick from the fumes generated when PCB gets hot. There are of course companies who recover the gold and other precious metals from scrap boards, it's good business with metals prices as they are.
For myself, it just ensures I have a good stock of parts every time I want to build something, and I don't often have to buy stuff. In Zimbabwe it was a definite advantage, but in Australia where parts are fairly cheap and there's overnight delivery, I wonder if I should keep doing it. But if I just want a couple of resistors and there's an $8 delivery charge, I still score!