Belt Replacement Tutorial for Sony Breadbox Cassette Walkman – Covers EX & FX Series
The internal mechanisms of Sony breadbox Walkmans are largely identical, regardless of single-sided or auto-reverse playback. They share the same drive belt specifications. Models such as the black-bodied FX101, silver FX121, FX4-series (FX415, FX413, FX211), and brushless motor models like FX173 all use the same belt. Therefore, the belt replacement procedure is identical for all these units.
Belt specs: cross-section thickness 0.8 mm; 0.7 mm also works. Folded length: 84 mm.
1. Disassembly
Sony breadbox Walkmans have no screws on the rear casing; the back cover is held by plastic clips and must be pried open manually. Procedure:
- Open the rear battery compartment lid and open the cassette door.
- Inside the cassette compartment you will see three retaining clips holding the back cover to the front chassis. Use a screwdriver or similar tool to gently push these clips to release them.
- Gently pry the casing apart starting from the battery compartment.
- If the cover remains stuck, reapply pressure to the three clips.
First-time disassembly on an untouched unit can be tight. Work slowly and patiently. Do not force the case open, as broken clips will prevent the rear cover from closing properly later.
2. Clean old belt residue
Thoroughly remove all degraded rubber residue from the motor pulley and flywheel grooves. Leftover gunk causes wow and flutter. Recommended method: apply isopropyl alcohol, wait briefly, then wipe clean with paper tissue or wet wipes.
3. Install the new belt
Once all rubber residue is fully cleaned, fit the new belt onto the pulleys. After routing the belt correctly, the replacement is complete.
Important note: This guide only covers belt replacement. Fitting a new belt does not guarantee the Walkman will work perfectly. Other faults may remain, including wow & flutter, hum / current noise, or distorted sound. I will cover troubleshooting these issues in future videos.
List of common Sony breadbox cassette Walkman models
FX101, FX103, FX105, FX301, FX303, FX313, FX305, FX315, FX121, FX123, FX321, FX323, FX325, FX355, FX171, FX173, FX373, FX375, FX221, FX413, FX415, etc. EX110, EX112, EX302, EX312, etc.
