This is one of my strangest Tech Tear Downs yet… My dad, my brother, and I cleaned up our backyard, filling up a Bagster all the way to the top. We went through an old junk pile, and buried underneath everything and covered up with leaves and dirt was the electronic guts of an old electronic organ that we trashed sometime around 2007. I was of course extremely curious, and despite the dirt, I salvaged the bulk of the electronics to see what they we’re made of or course to see if there was anything useful.
Basically, there was four large PCBs stacked and bolted on top of each other. They consisted of diodes, transistors, resistors, and capacitors, as well as a few op amp ICs. Other than on the top layer, there was little corrosion on the components, and I wondered as to how useful they would be, considering that they’re from the 80s and they’ve been subject to very extreme temperatures, as well as water.
I was excited to see that there was loads and loads of diodes (the image above shows a section of one PCB after I removed a bunch of the diodes; they were easy to get to). I would estimate there was close to 80 silicon diodes that I could have used in a breadboard. I set a table and got out all my tools and spent a while removing the diodes and a few of the resistors, using mainly a small flat-head screw driver and needle-nosed pliers. I was able to get maybe 50 diodes, a few resistors, and a few transistors, as well as a few useless souvenir ICs.
I tested a few of the diodes out, and they worked great. The transistors were junk, and most of the resistors had leads that were too short. But now I have enough diodes to make a decimal-to-binary converter!
Above is where I was working.
There’s a few differences I noted between these four giant PCBs and modern day ones. First, the etched copper connections were very curvy, instead of rectangular and crammed together as you see on modern machine-made PCBs. Secondly, the wires coming off the PCBs weren’t directly soldered onto the board. Instead, a little metal spike pokes out of the board and the wire wraps tightly around the spike, so the joint is more mechanical, as you can see in the picture below.
Quite frankly, I don’t really know how these PCBs work inside the organ. They were labeled in a few spots as having something to do with ‘rhythm’ and there was a large mass of wires exiting the PCBs, so my guess is these boards were responsible for generating the different tones on the organ.