Repaired a SONY WM-EX57, bought broken for 12 Euro. https://walkman.land/sony/wm-ex57 Steps taken: 1. Replaced capacitors C112; C212 (one shorted, the other just to be safe) - surface mounted were the only ones that would fit. That restored sound to both channels 2. Changed the belt, the old was turning to glue. (great belt from https://fixyouraudio.com/product/belt-sony-wm-ex57/ - got here fast, worked perfectly, thank you). 3. Repaired several traces on the board. Strangely enough traces not under stress were broken (in an otherwise pristine machine, no visible signs of trauma anywhere). 4. Ohm-metered through the output and volume control stages, checked out OK. Remaining issues: Now it runs smoothly and sounds really great (among the better ones) - but a strange volume control fault remains: On max volume it delivers good stereo - but on lower volumes less and less stereo. And the on-board volume control won't go to Zero. Normally this could happen with a failing ground connection, but I checked all traces and they seem OK. It's perfectly usable with a on-cable-volume control, so I might stop here and count my blessings. Still... and here really I ask for advice - the volume design on this Walkman appears more complex than a regular level control between amplifying stages. Anyone here repaired something similar? Possible plans: 1. I'm getting a proper ESR capable meter soon... just measuring the capacitance can be misleading when caps fail in Equivalent Series Resistance (ESR). 2. Double check capacitors again (the 22 uF are hard to replace, possibly 5*4uF (surface mounted) in parallel could work, but a bit tricky. My local supplier only had 4uF surface mounted. 3. Still, while this was a fantastic machine to work on (cool to see how Sony retained the chip designations for audio and motor control over the years), really a tech marvel - the board won't stand too many disassemblies. I accidentally pushed the board connector for the lid controls out of place (managed to superglue it back and resolder all connections with one decisive touch with a very clean soldering iron). I got lucky there, but I'm probably running out. So, tips on this strange volume control would be of great help. Thank you! Enclosing closeups:
All capacitors laid on one side need to be replaced, this type goes bad all time. These can be replaced with SMD tantlums which will fit nicely. Note on SMD tantalums the marked side is the positive, opposite to electrolytics. You can find them at TME or other major distributors: https://www.tme.eu/en/details/taja226k010r/smd-tantalum-capacitors/kyocera-avx/taja226k010rnj/ In my opinion not worth getting an ESR meter for this job, it's easier to just replace the capacitors.
Thank you @Valentin ! Well, I might just do it. I modified the remote with a 3.5 mm stereo female to connect other headphones that way - and went for a run. Amazing little Walkman... hardly any audible "flutter-bumps" when walking, and even when running fast the sound kept really good. The sound is so much deeper (spatially) when recorded analog and never compressed digitally.
