Sony WM-AF64/WM-BF64 Walkman Repair

The WM-AF64/WM-BF64 usually requires repair if the cassette audio is very faint or not present at all, and it is usually to do with faulty capacitors. There was a time when a particular manufacturer made poor quality capacitors that leaked, and if your Walkman has these capacitors, then it will result in poor audio and insufficient volume. The indicative signs are motor-boating and choppy audio due to insufficient capacitance within the power planes. The signs are almost as if the batteries have depleted, however the problem will persist even with new batteries.

Capacitor List

This table shows the value of the capacitors indicated in the diagram at the top of this page. Each capacitor has a number that you can refer in the table above.

Whilst the radio produced some sound, the cassette audio was extremely low even at full volume. If you switch OFF the Dolby, and the set the dynamic bass boost (DBB) to normal, the sound might improve somewhat because as the power consumption of the circuits reduce, and the capacitors have to work less. One interesting experiment worth trying is temporarily bypassing C103 or C203 (with a short loop of wire), which should result in an increase of audio level.

The radio worked to some extent, however when the volume was increased the sound became choppy and fuzzy. This clearly indicated that the electrolytic capacitors in the power amp section had diminished. C314 and C315, which are 220 µF/4 V, are usually the cause of this issue.

Since the audio was very faint when playing cassettes, the likely suspects are C301, C302, C103, and C203, within the preamplifier stage. Usually in situations like this, it is better to replace all the capacitors, because even those that are not leaking may leak in the near future. This is probably the time for capacitor upgrade to improve the sound as well; however, I just wanted to get it working and therefore bought a bag of assorted SMD electrolytic capacitors for three pounds on eBay. It took a couple of weeks to arrive from China, but was well worth the wait.

Whilst waiting for the delivery of the capacitors, I started tinkering with the circuit to see what modifications could be made to improve the sound, and therefore checked the position of all the capacitors and their function within the circuits. I already had some recycled capacitors that were sufficiently small enough to fit and therefore could not resist the temptation. In this design, the power amplifier IC requires output capacitors (one for each channel), and they are C117 and C217. If you wanted to make a minimal restoration, then changing these should improve the sound to some degree.

Soldering Skills Required

In order to remove the faulty capacitors and solder new replacements, you will require experience of soldering SMD/SMT components. There are 15 capacitors to replace and solder and if you are a beginner, then this will be challenging. If you have poor eyesight and hand coordination, then do not attempt this repair as you may make a mess of it. Instead, it is better to sell your Walkman on eBay, and anyone interested in having a go with this repair will buy it.

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