Many of you have read my post about the Magnavox D8443 boombox which details my history of ownership, along with the state of that model boombox as it pertains to those who collect them today (http://vintagevolts.com/?p=328).
One of the biggest issues with these boomboxes is the deteriorating condition of some of the gears which drive the cassette mechanism. The gears are made out of an inferior quality of nylon which tends to turn very yellow (a form of oxidation), eventually turning brittle and breaking. When this happens, the cassette mechanism is rendered useless.
When I got my replacement Magnavox D8443 on eBay last year, it too had the same problem. I knew about its issues, but I was determined to get the boombox as cheap as possible and figure out a way to get the gear replaced. I did have the original gear, but it was missing some teeth and was broken in two. I tried to create a resin casting from clay so I can cast a replacement gear using a clear resin kit that could be found at most art supply stores. I found it very difficult to produce the gear mold. Nor was I able to conceive a finished product that would not have required a large amount of “finishing” in order to get the gear working right.
What ended up working for me was gaining access to high-end 3D printing system in order to get some “samples” made. So, I tapped my resources to create an accurate model of the original gear, then had a couple of gears made for me to test extensively. Version 0.9a of my gear design actually turned out very well. Not perfect, but very well. I was able to get the gear installed in my D8443 and run cassettes in it over the next few weeks. I ran about 50 tapes through, both sides, and the gear performed wonderfully. Afterwards, I tweaked the design (version 1.0) and had more gears created. I tell you, this isn’t some cheap desktop 3D printing contraption doing it (as much as I WISH it could have been) because the resolution needed for the tiny gear teeth was beyond the capabilities of DIY 3D printing solutions. A high-end professional 3D printing system was used instead. The newer batch of gears were very detailed. I installed one in my D8443 and it worked just as well as the prototype design.
Now that it turns out to be a suitable replacement gear, I am making the gears available for sale to other collectors whose D8443s have the same issue. I have found a reputable manufacturer that lest me sell them at a lower price. You can now buy as many gears as you want/need here:
I (hurriedly) produced a 30 minute video which details the disassembly of the Magnavox D8443 and replacement of the damaged gear. The video can be found at: http://youtu.be/p4YuYZVYIX8