Sony WM-EX670

The WM-EX670 and WM-EX672 cassette Walkmans were manufactured in approximately 1999 by the Sony Corporation in Malaysia. Both units were identical except that the latter model was a special edition version supplied with LCD remote control. This multi-page article shows the former model, including its features and specifications.

• Full Metal Body
• Mega Bass, Groove, Sound Revitalizer
• Automatic Music Sensor (AMS)
• Automatic Volume Limiter System (AVLS)
• Blank Skip / One song repeat
• Dolby B noise reduction
• Groove Headphones
• Dimensions: 77.7 mm × 109.1 mm × 21.4 mm
• Mass: 140 g (without batteries or cassette)

Review

By the years 1999 and 2000, semiconductor technology was highly evolved, and consequently this unit had an extremely advanced chipset. I am always particularly impressed with the system controller, which is a 4-bit microcontroller capable of operating with just 0.9 V. Even more impressive is the low power consumption as this unit is capable of operating for approximately 39-hours with a Sony alkaline LR6 (WM) battery, and 12-hours using the NC-6WM rechargeable battery. Of course, both batteries could be used simultaneously to provide approximately 50-hours of operation. Here is a list of some of the main integrated circuits in this unit.

• TA2123F master amp by the Toshiba Corporation
• NJM2185AV Dolby B noise reduction by the New Japan Radio Corporation
• MM1279XVBE 3-phase motor driver by the Mitsumi Corporation
• ML63512 System controller by OKI Semiconductors

This unit has one of the most advanced tape transport mechanisms (TTM), which was very much a new development for this model. It employs a 3-phase disc motor with its own driver management IC. It also uses a rotation detection photo sensor (PH701), and solenoid. This TTM has a single drive belt that is easily accessible, making it easy for an engineer or experienced hobbyist with soldering skills to change it. You can see photographs of this and more in the following pages of this multi-page article.

The sound quality is excellent providing you find a good unit and use a good pair of headphones. The most important function in this unit is the sound revitalizer, which brings life back to your old faded cassettes. This was probably one of the most advanced developments in sound technology, and one of the last significant milestones.

The "FUNCTION" button is pressed in combination with other buttons to select the desired mode.

As you can see, they still provided a socket for connecting the remote control.

Price/eBay

This unit sometimes comes up for sale in various conditions, and condition is everything when determining the price. Just the unit on its own that is badly scratched and non-operational will not be worth much more than just the sum of its parts. If you are looking to buy one, then there are various things to consider such as how you intend to power it. The NC-6WM rechargeable battery will by now be well past its useful life period. Without the special charging adapter accessory you will not be able to charge it anyway. However one thing you must make sure is that it comes with the AA battery holder/adapter which screws to the side.

If the unit is in mint condition together with its headphones, remote control, charger and box, then it could be worth a small packet on a good day. I have seen people pay more than fifty pounds, and on a good day, even more.

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