Sony WM-F10

Sony printed the WM-F10 manual in Japan in 1983. That was the year the Walkman shrank. According to Nippon.com's history of the player, the WM-20 that went on sale in 1983 was the size of a cassette case. The WM-10, released late that year, was smaller still and had to be slid open before a tape would fit. The WM-F10 belongs to that generation. It is the FM version: a stereo cassette player with a tuner for 88 to 108 MHz, and no AM band. Sony's manual gives its size as about 111.5 by 74.8 by 22.3 mm, and its weight as roughly 200 g with the battery. The hard part was power. One AA cell gives 1.5 volts, which is not much to run a motor, an amplifier and a radio. Collector references on the WM-10 describe a step-up DC-DC converter that raises that voltage. The WM-F10 runs from the same single cell, with a 1.5-volt DC IN jack for mains or car power. Two details show how much Sony packed into the case. One small switch sets FM sensitivity and also turns Dolby NR on or off for tape. And there is no power switch at all. The manual says the player comes on when headphones are plugged in and goes off when they are pulled out. The headphone cord also works as the FM antenna. The surprising part is where one ended up. Museum Boijmans Van Beuningen in Rotterdam keeps a WM-F10 in its applied arts and design collection. The museum dates it to around 1983 and acquired it in 2009.

Listening to cassettes and FM radio from something that fits in a jacket pocket. The keys are mechanical, so play, stop and winding work by feel. Playing Dolby-encoded tapes as they were meant to be heard. Sony gave it a Dolby NR switch and a tape selector for normal or metal and chrome tapes. Showing how far Sony pushed size in 1983. It weighs about 200 g with its battery, and the body is metal. Where it falls short It is a player, not a recorder. Sound comes only through headphones, and the headphones are also the on switch. The radio is FM only, from 88 to 108 MHz. There is no AM band. Because power depends on the headphone jack, a worn jack can make a working player look dead. The parts are small and packed tight. Owners on the Stereo2Go forum describe the WM-F10 as fragile, and a bent case can make the drive drag. Expect the original rubber belt to need replacing before the player runs reliably. Sony's manual also warns against loud, long listening and against using headphones while driving or cycling.

Plug in headphones first. The WM-F10 has no power switch: Sony's manual says power comes on when headphones are plugged in and goes off when they come out. For tape, set the function selector to TAPE (RADIO OFF). Then fit a fresh AA cell and look at the battery contacts for white or green corrosion.

Hold the player close to your ear. The Stereo2Go repair guide for this family of Walkmans says a running motor with no tape movement most often means a snapped or slipping belt. A jammed belt can also stop the player from powering up at all.

A stretched belt is the usual first suspect, according to owners on Stereo2Go. A bent case or chassis that lets a pulley rub can cause the same symptom. Clean the head and pinch roller before judging the sound. Sony's manual asks for that after every 10 hours of use.

A scraping sound points to the felt spacer strips inside the metal shell, which turn powdery with age. A click once per turn of a spindle points to a cracked gear. The Stereo2Go guide names that gear as a known weak spot in this family.

Move the headphone plug gently in the jack and listen. The jack is fed through a flexible circuit board that can break in one line. The jack pins can also have a cold solder joint.

Set the function selector to RADIO and the FM sensitivity selector to DX. The manual says to use LOCAL only when a strong station causes noise. The headphone cord is the antenna, so try another pair before blaming the tuner.

Cause: the rubber drive belt stretches, slips or snaps with age, even in storage. Owners on Stereo2Go name it as the most common reason a WM-F10 stops or runs slow. Fix: a new square-section belt. Replacement belts made for the WM-F10 are still sold by parts suppliers. Who: possible at home with patience. The Stereo2Go guide lists two hinge screws for the cassette door and four chassis screws to open it. The parts are tiny, so a repair shop is the safer choice for a first attempt.

Cause: a leaking AA cell left inside. Sony's manual says to remove the battery when the player will not be used for a long time. Fix: light corrosion can be scraped or dissolved off the contacts. In bad cases, the Stereo2Go guide says corrosion can eat through the solder joint of the wire from the negative terminal to the circuit board. Who: cleaning contacts is DIY. Resoldering that wire is bench work.

Cause: a broken line on the flexible circuit board that feeds the jack. A dirty switch contact or a cold solder joint on the pins does the same. Because the jack also switches the power, any of these can make the player seem dead. Fix: contact cleaner for the switch. A broken flex line can be bridged with a fine wire after scraping off the varnish, and dry joints can be resoldered. Who: cleaning is DIY. Flex repair needs a fine soldering iron and a steady hand, so it is usually repair-shop work.

Cause: Sony fitted felt spacer strips inside the metal shell to keep moving parts from rubbing. With age they turn to powder. Fix: new felt strips, which the Stereo2Go guide describes as easy to replace. Who: DIY once the case is open.

Cause: the gear under one spindle is prone to cracking, which gives a click on every turn. Fix: a replacement gear, which repairers describe as awkward to remove. Some rebuild the split area in place with epoxy putty. Who: repair-shop work.

Cause: a drop or pressure that bends the thin case or chassis, so a pulley rubs on something. Owners report slow, wavering playback as the result. Fix: straighten the frame and realign the mechanism. Who: repair-shop work, because the frame and the mechanism sit very close together.

Cause: the Stereo2Go guide links unstable speed to the motor and to failing capacitors. Fix: the Stereo2Go guide describes a speed adjustment that can raise or lower playback speed to match the correct pitch. Who: a small job with the case open, but it needs a known reference recording to set it by ear or by meter.