Reviving a Sony WM-FX28 Walkman

I had been looking for a small restoration project, something with electronic and mechanical components that could be completed in less than a day, when I stumbled upon some YouTubers who still use audio cassettes.

It reminded me how much I obsessed over audio equipment as a child. Every time a family member upgraded their stereo systems I would beg for the old components, and by the time I was a teenager in the late 90’s I had built an absurdly mismatched setup in my media tower.

Part of that system included an old wood-panel tape deck complete with needle meters. I never had many commercially produced cassettes, but I had stacks I’d recorded myself. I loved recording video game music to listen to on my walkman, or dictating story ideas through the set of “professional” microphones I’d scrounged.

So, watching these YouTube videos, I started to get a better understanding how cassettes and cassette decks work. I enjoyed seeing that, if you knew what you were doing, you could actually make pretty high quality recordings on cassette.

Which, by the way, taught me that I was doing everything 100% wrong as a child. Oops.

Now, I don’t have any old cassettes to play, nor do I have a pressing need to set up a full deck for recording, but after some deliberation, I decided that I wanted to try my hand at fixing and restoring a walkman. Nothing fancy, not the golden-grail best player desired by current cassette collectors – just take a regular broken walkman and get it up and running again.

I searched eBay for options and finally settled on this Sony WM-FX28:

The listing said the radio worked but the tape didn’t, and it was only $10 before shipping. I looked around online and was able to find PDFs of both the Sony WM-FX28 User Manual and the Sony WM-FX28 Service Manual. So I went ahead and bought it.

The number one reason a cassette player stops working is that the rubber belt inside has worn out, stretched, or just straight up broken. It’s a simple repair – if you can get the right sized belt. Thankfully I was able to find a Sony WM-FX28 replacement belt online for cheap. The other thing you need to do (especially after replacing a belt) is to calibrate the speed of the motor, so I just added a speed calibration test tape to my order.

Now the site I bought these from, Fix Your Audio, is one of the few (if only) places left in the world where you can reliably get these kinds of replacement parts for cassette equipment. It’s located in Slovakia, but I was pleasantly surprised that it only took a week for the package to get to me in the USA.

The last tool I ordered was a Cassette Head Demagnetizer. As tapes play, the magnetic material in the tape can slowly magnetize the cassette head (the part which rubs against the tape to read the signal). This will affect the quality of the sound, but more importantly, a magnetized head can potentially erase a tape as it’s playing. So it’s important (especially when getting a used player) to demagnetize the head so it won’t ruin your tapes.

Speaking of, even if I got the walkman working, I didn’t have any cassettes to actually play on it. So I started hitting up eBay and Discogs looking for Hawaiian cassettes. I was able to get a (still sealed) copy of Hawaiian Slack Key Guitar Masters along with a copy of my all-time favorite album: Mākaha Bash 3: Live At The Shell.

With all my orders in place, it was time to clear some desk space for the project. The first things to arrive were the walkman itself, the replacement belt and calibration tape, and the copy of Mākaha Bash 3:

As listed, the radio functioned just fine, but nothing moved when pressing the tape controls. So, following the service manual, the first step was to pop off the back shell:

Oops! As you can see, I got the shell off, but at the expense of a few of the plastic tabs that attached it. I probably should have been a little more gentle with the old plastic, but I also think the service manual deserves some blame here. I exaggerate, but step 1 is like “insert screwdriver here to separate the shell”, step 2 is “open the tape door and release this tab” then step 3 is like “in step 1 you should have removed the shell in this exact order”.

Anyway, there’s still plenty of tabs left, so next I took a look at the mechanism itself. Looking closely at the motor on the right, you can see where the belt is tangled around the shaft, rather than looped nicely around the brass pulley:

Adding batteries and pressing play, you could see the motor trying to run but the belt was just getting caught tighter underneath. Removing the belt allowed the motor to run quite freely:

Disregarding that growing pile of broken plastic bits from my bad shell removal, you can see how much the old belt stretched by comparing it to the replacement side by side:

With the belt out I took a moment to clean things with some compressed air along with good ol’ cotton swabs and isopropyl alcohol. Then I installed the new belt:

With the new belt in, I reinserted the batteries and tried the controls. Play would run the gears but that little white arrow in the center kept snapping back and forth with an awful clicking noise. Fast-forward would only run for a second before stopping, while rewind caused the the whole thing to lock up while the motor spun away, rubbing on the belt but not getting any traction.

I couldn’t see anything that looked straight up broken: no missing teeth on the gears and no stray bits of plastic that I wasn’t responsible for. I continued my search (and cleaning) by popping out the entire board and checking everything underneath:

Finally I decided my best bet was to try lubricating all of the gears. I used the plastic on plastic grease I’d bought for when I eventually tune-up the floppy drives in the macs I’m still restoring:

I made sure to get the grease onto the shaft of every rotating part in the mechanism. After I was satisfied that I’d gotten it everywhere it needed to be, I popped in the batteries and tried the controls again:

Sony Walkman WM-FX28 with new belt and greased gears

It worked! Play, fast-forward, and rewind all ran perfectly with no clicks or hang-ups. I really wish I’d had the presence of mind to record how it ran like before the repair, but c’est la vie. With the mechanism working again, I put the whole thing back together, thankful enough plastic tabs remained for it to stay together.

The next step was to demagnetize the head. According to the instructions (and people online) you want do this far away from any kind of magnetic media, as the demagnetizing wand is basically a wall-powered electromagnet. In the age of solid state drives that might not be a risk in most modern offices, but with my other retro restorations I’ve actually amassed a small assortment of floppy disks and hard drives in my workspace. So it’s off to the dining room table:

To use the wand you have to plug it in several yards away from the target, approach it very slowly, touch the items to demagnetize for roughly five seconds each, then back away slowly and unplug it back where you started. If you go too fast, or touch the wand on the head for too long, or cut the power while you’re still too close, you risk doing the exact opposite of what you want and magnetizing the head even more.

So I propped open the cassette door and dutifully snuck up on my unsuspecting walkman like I was pranking it while it slept. Who said electronics restoration wasn’t exciting?

With that finally out of the way, the last step was to calibrate the speed of the motor. The idea is to play the calibration tape, which has a 3 kHz tone recorded onto it, and verify that the pitch isn’t too high or too low. You use a tool called a “frequency counter” to see the exact frequency being played, and adjust the speed of the player’s motor until the tone is exactly 3 kHz.

I don’t have a physical frequency counter, but thankfully there’s plenty of free smartphone apps that work just fine for the job. Also this particular walkman exposes the speed adjustment potentiometer through a tiny hole in the back of the case, making it easy to adjust the speed without having to take everything apart.

So I inserted the calibration tape, connected headphones, cranked the volume, and installed Audio Frequency Counter onto my phone. The app picked up the signal at a few hundred kHz too fast, so I adjusted it down with a tiny screwdriver until I was as close as possible to 3 kHz:

Finally, after all that work, I put in my Mākaha Bash 3 cassette, took a deep breath, and pressed play:

It worked perfectly! I listened through the whole album, both sides, without any issues. I made lunch while listening through my very anachronistic modern earbuds, since I don’t have any old over-ear style headphones.

After that first playthrough I did redo the speed calibration just in case things had loosened up, but otherwise, I think it’s safe to call this repair is complete. Despite some missing bits of plastic, I’m happy with the results.

Now the only question is: do I stop here, or do I need to take the next step and get a cassette recorder up and running? We’ll see.

/jon

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