Electronics, Flea Markets, Tape Players

Sony WM-EX19- Belt Replacement

Found this beaten down Sony WM-EX19 for a very good price and I decided to buy it. The seller didn’t even know the price, he had to ask the family to find out 🙂 all this happening at a jovial neighborhood flea market.

Table of Contents


The player lacks the belt clip, but looks clean:

The label was torn (see left photo below) thus, what is the model ?! Was convinced it is a Sony WM-FX19 (and surprisingly, that model exists too). Somehow my brain saw the torn E like an F and it never occurred to me that it can be an E. I realized my mistake later, having opened the device and spotted the marking on the motherboard:

A quick test revealed that the player did not work. I could hear a spinning motor sound, but no movement. I was hoping it is just the belt that need replacement, since I have plenty belts from those sets that have tens of belts of various sizes.

Opening Up

Opening up is straightforward, there are instructions and the service manual is available online. There are various clips that hold the two sides together. It is easier starting from the center clip (accessible via the Tape door).

Once inside, it was obvious, the belt was too loose. Thankfully, it didn’t melt allover, it was just sticky:

Sony WM-EX19 – Loose Belt

One more thing to note, there was some corrosion on the Battery Plus terminal, maybe because of the old battery that I found inside ?

Corrosion Cleanup

This was easy with some Isopropyl Alcohol, a cotton bud and a thin metal scraper for the hard to reach parts. I covered the metal part with a bit of sewing machine oil, in the hope it prevents further corrosion.

Belt replacement

This was the most time consuming part. Since the the original belt was still intact (albeit loose), I could still measure its width. 0.8mm width and around 6cm diameter.

My bag of many belts did have a 6cm diameter belt, but only at 0.6mm width. W&F was allover the place, the motor was just too strong for the thin belt.

I turned to ebay, but none of the sellers list the belt diameter / width. They only the model of the device that it is for. One of the sellers responded that it is an 0.8mm width so I ordered one. I also found a shop on Aliexpress that was selling 0.8mm belts, and I ended up ordering 2 of each length around the 92mm “folded length” that they were asking (92mm is around half of the circumference of a 60mm diameter circle).

The best W&F ended up to be the belt called “88mm folded” from the Aliexpress shop.

The 0.8mm is obviously more suitable once you see how the motor deforms the 0.6mm belt.

For testing, I used a 3kHz tape that I bought a while back from FixYourAudio:

However, the WTD measurements are very poor – even after oiling the motor, the capstans and replacing the white grease on the center wheel.

The values oscillate between 0.25% and 0.35% WTD JIS Standard (JIS standard, since I had a 3kHz tape). Switching to W&F shows between 0.45% and 0.55%:

Measuring Sony WM-EX19 Walkman Wow and Flutter with Leader LFM-39A

I’m not an expert by all means. I chose JIS, because running a 3kHz tape pegs the meter needle if DIN button pushed in.

I repeated the measurements with WFGUI and it shows similar numbers:

WFGUI is a very nice application, but can be improved since it is rather unintuitive. Many people online seem to ask the same clarification questions, what do the value represent ? The responses are even more confusing. I just had to take out the real meter.

As Input for WFGUI I used a Behringer U-Control UCA222 USB Audio Interface.

The Sony service manual does not list the W&F figures. I checked even the service manual of the WM-FX19 (which seems to be the same, except is has Radio) and they are missing there too. So I can’t tell if the belt replacement got this one closer to manufacturer specs.

More cleanup

The motor still had a bit of remains from the original belt, I did my best to clean with a cotton bud + IPA (switched to a tooth pick for the deepest groove):

I also added a bit of sewing machine oil – to grease the motor, as it was the thinnest oil I had. Saw suggestions of using watch oil, which I ordered meanwhile. I doubt the oil made a W&F difference, measures before and after showed no discernible improvement ..

I replaced the dried white grease on the center wheel with a bit of Teflon Grease. And it does feel weird to use grease meant for bike chains ?! I use silicone grease for plastic to plastic or metal to plastic, but somehow silicone grease feels too ‘sticky’ to touch and to be used for this lightweight mechanism. I figured I may try PTFE just to see. Seems to work fine, again, no improvements to the W&F before or after.

Capstan, the pinch roller and play head were were also cleaned with IPA. Slide switches and volume pot got a spritz of Contact Cleaner:

After all the work and the struggles to obtain a belt, not sure if it was worth the effort … as it can’t seem to run under 0.25% WTD and speed is unstable. I didn’t change any capacitors nor tried to take the motor apart, but I am not tempted too. I will look for similar Sony models at flea markets, should one come my way I’ll buy and compare. I mean, it may be that this one is faulty, but I don’t have a similar one to compare it with.

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