I assume you have one of these supplies which is why you want to know the voltages. Each of the supply voltages is marked on the PCB where the wires connect. It would be better for you to get the information that way as they could have changed the wire colors.

David

On problem I have experienced with the shake or bump method to remove the parts is that you end up with big splashes of solder across the pins on the salvaged parts. It is easy to clean up but you will end up wanting to clean them all before you sort them into your collection.

I tend to keep the boards I want to scrounge from intact and just go after the parts I need. The come off cleaner and I don’t spend much time cleaning and sorting. Of course, I don’t always know what parts I have this way.

One idea I wanted to try was using a skillet and some sand. I have seen this done before for single sided through hole PCB scrounging. Basically you just put some clean sand in an electric skillet and heat it up. Put the PCB in the sand and use a broom handle to push the PCB down into the heated sand. Use long nose pliers to pull out the parts.

This should also work for surface mount parts but the parts on the sand side of the board might get lost in the sand.

Though this technique only works with boards where component leads have not been formed, and there is enough loose play clearance. When it does work well, the parts come out like rain. I should add one tip though, with any of the beating, or slapping techniques beads of molten solder are released from the board too, if you don’t pick up your parts, or sweep them to the side or something, you will end up with some parts getting beaded in the next cycle of the process.

Also, some strategy comes into play with bulk desoldering. Heat is destructive to all components in great enough quantities, or duration. So, plan your attack to liberate the most heat sensitive, or desirable parts off a board first. Typically I will go after semis first, then capacitors, then resistors. As their name would imply, resistors can really resist some heat usually.

Many scrounged parts are of a higher quality than an experimenter can typically buy. Professionals assembling PCBs often have better sources for parts than amatuers. Some of the obsolete tech from the 80s that cost tens of thousands of dollars when it was new was put together with some pretty nice stuff! I have scrapped a couple of ancient mini computers, unreal the components in those. Junk boxing as it is called is a time honored tradition in the electronics hobby community. You’ll always have to buy some parts, but the more you can dredge up out of your junk box the greater the pride of accomplishment, for me at anyrate. Any idiot can spend money I always say.

I’m glad to see that you folks aren’t wasting your time trying to use soldering irons to bulk desolder PCBs. I did, I suppose we all have, it doesn’t really work. Desoldering rework stations are for when the PCB is still the most valuable component in an assembly, when it comes time to scrap something for parts, I say throw another PCB on the barbie!