I bought a bunch of old transistor radios (portable, hand sized0 from yard sales. most of them work, except that the volume control pots are worn and scratchy. Is it possible to get pots to replace these? most of these radios were built from 1958-1970-so the original parts are probably long gone.
have aI stumbled on a new collectable? are these ever to be worth anything to collectors?
Unless you get lucky you will probably have difficulty finding replacement pots which will be exactly alike mechanically but the problem is only mechanical. On the other hand the problem with pots is mostly dirt and they sell special sprays for cleaning them so it may be possible to get them back to good working order. I have a few old radios and alarm-radios with that problem and I never get around to doing anything about it. I just fiddle the wheel until I get a volume which is acceptable. Those old transistor radios are not worth much in terms of money but there are a few people and amateur museums who would collect them and repair them for sentimental value. I have repaired quite a few and even have some original new germanium transistors.
Have you tried a good shot of Circuit cleaner?
If that doesn’t work:
Taiwan Alpha Thumbwheel Potentiometers
You’d best be good with a soldering gun. Those old circuit boards can get brittle and funky.
It isn’t the boards themselves which are problematic–just handling them gently is sufficient–it’s the circuit traces. Overheating can easily break down the already-degraded epoxy bonding the copper to the substrate causing pads and traces to lift up, and if you’re not careful, tear away when you remove the part. Luckily, these are single-sided boards, so you don’t have the problems inherent in desoldering plated-through holes (namely, pulling out the through plating along with the part pin), so a bit of care with your desoldering technique should largely preserve the circuit integrity. This is where solder braid really shines; having a good vacuum desoldering pump doesn’t hurt, either.
To the chagrin of my coworkers, I consider those plunger-type solder vacuum suckers to be evil. If you’re not careful you’ll end up sucking the copper trace right off the substrate. IMO, braid is the only way to go. One secret when using braid… melt a little bit of solder directly onto the braid first. This will enhance thermal conduction.
They’re fine for what they are; I use them myself. Likewise, solder braid is fine for what it is. Plunger suckers are great for getting solder off large joints or from inside plated-through holes, while braid is great for getting the last traces of solder after using a vacuum sucker or SMD work. Of course, for most work nothing beats a variable-suction hot air rework station, like the one we use at work. Hot air has much less chance of lifting up traces and pads and the heated suction tip with one-handed operation means I can turn the board over and let gravity assist when sucking out through-hole joints, cutting the risk of pulling out the through plating dramatically–massively critical when working on multilayer boards.