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PUBLISHED 7/21/2024
WRITTEN BY Christopher McRae
While most people have moved on to more modern forms of technology for listening to music on the go, there remains a group of enthusiast who continue to use cassettes on a regular basis. Sony's Walkman has always been a staple of "cassette culture", and is one of the first devices to allow for personal listening anywhere. While most enthusiasts prefer to discuss and use the more notable models in the Walkman range such as the Walkman Professional, the DD series, and of course the TPS-L2 (the original model) due to their feature sets and overall quality, attaining one of these models in the present day can be quite expensive, especially for a fully functioning model. For example, the price of a WM-DD9, regarded as the best Walkman model ever made, can easily surpass $1000. The Walkmans that most can afford are often overlooked, these models are primarily constructed of plastic and are definitely not as classy or memorable as some of the previous models mentioned. But many of these devices can produced good sound quality if properly maintained.
Over the years, I have collected quite a few model of Walkman made between 1990 and 1995. These models, from my experience seem to be the most plentiful when shopping at thrift stores and on eBay. Models like these, such as the WM-FX38, or WM-FX-407, generally use the same mechanism, with minor differences that make swapping certain parts impossible. They generally have similar feature sets, Auto Reverse, FM/AM radio with presets if equip with a digital tuner, AVLS (Auto Volume Limiting System), with more advanced models supporting Dolby B NR, MEGA BASS, and tone control. In this article I will feature the WM-FX407, my "daily driver", which I bought off eBay for less than $20 back in 2020. As of writing this article, I use this device everyday and have probably spent a conservative estimate of 300 hours listening to music with it. This model is feature packed and is only really missing tone control, which only seemed to be offered on models with analog radio tuners.
My daily driver Walkman, the WM-FX407
One major issue with cassette players in general is wow and flutter. When the tape transport system becomes dirty or wears out, most likely both cases, your audio may start to sound wobbly and inconsistent. This wobbliness is referred to as wow and flutter and is an issue that plagues pretty much any electro mechanical or mechanical audio reproducing device. On cassette players, a very likely cause of this issue is when the capstan (metal cylinder device that drives the pinch roller) becomes polished. When in proper shape, capstans have a dull grey finish that allows for a lot of friction, this friction is required for proper playback. After extended use, the capstans will loose their finish and become shiny and polished. At this point the capstans need to be resurfaced or replaced. In this article you will see how to replace and maintain capstans on these budget Walkmans.
Left: good capstan with minor wear. Right: polished capstan that should be resurfaced or replaced
After opening up the case and removing the belt, carefully pry the pulley of the capstan you want to replace upward. Be careful not to damage the components you are prying against.
Now push the capstan through by applying force from behind.
Now that the capstan is no longer secured, you can pull it through the top of the mechanism. When installing the the new capstan, push it through the bottom, you may need to use a hard object as a surface in order to push it in.
Another issue that tends to plague older audio equipment is potentiometer failure. Sometimes this is just due to oxidation building up within the pot, and in that case spraying a cleaning product like DeOxit will remedy the issue. In more severe cases, however, replacing the pot may be the only solution. In the case of my WM-FX407, the volume potentiometer, after being cleaned a few years prior, devolved issues that resulted in an almost complete loss of sound. As a temporary fix, I bridged a few of the terminals on the pot in order to fix the volume at 100%, I then relied on the AVLS feature, which I had never used before, to "control" my volume. But after several months, I became tired of this issue and decided to finally replace the pot. Below is the process by which I used to replace it.
I first picked a specimen to harvest a potentiometer from, the WM-FX41 had a similar, albeit larger, pot with that was surface mount, similar to the FX-407’s pot. This is another one of the small differences between models of Walkman built during this period, some used surface mount pots while other used a more traditional "through board" pots.
Before desoldering (left). After desoldering (right). I trimmed part of the ground shield in order to fit the new pot on the FX407's board.
Next, it was time to remove the volume potentiometer from the FX407 and clean up the contact pads.
Prior to removal (left). After removal (middle). Pads cleaned up (right)
You can see the slight "modification" (left) I made in order to bypass the volume control so I could continue to hear audio despite the faulty potentiometer. I also accidentally touched the capstan pulley with my soldering iron and deformed it, I ended up replacing it with one from one of my parts walkman.
After soldering the new potentiometer in the FX407, the casing would not fit due to large size of the new volume knob. I ended up cutting away at the casing in order to make it fit. Here is the final product:
The volume control sticks out a little bit.
Overall, I am pleased with the results of this project. As some one with no surface mount soldering experience, I am glad that I didn't destroy anything while trying to remove the pot from the FX407. If I can do these kinds of repairs, anyone can. I hope this article is helpful to someone out there. If you have any questions, feel free to check out the about section of this website, there you can find my contact information.