Sony WM-F701C back to life

Discussion in 'Tech talk' started by nutronic, Jan 4, 2025 at 4:04 PM.

  1. nutronic

    nutronic New Member

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    This was my restoration project over the Christmas break. I was hesitant to even attempt this one, considering the state of the capstans and evidence of battery leakage - but it didn't look as bad on the inside, so decided it was worth a try.

    First problem - it was dead on arrival. Eventually traced the no-power fault to a shorted burnt-out coil in a tiny surface-mount transformer, hidden inside the DC-DC Converter module. I've posted another thread on this.

    With power now restored I tackled the cassette mechanism. The rusty capstans cleaned up surprisingly well with steel wool, and I borrowed a pair of pinch rollers from a sister model. Strangely, one of the pinch roller arms was tight on its axle and would not retract when reversing playback direction. I've had to file down the shaft (which also forms part of the head bridge) to give it some clearance.

    The motor was noisy so I've dismantled it and lubricated the bearing. One of the reel spindles was also stiff, which I traced to dried-up grease on a tiny idler gear. Accessing this requires the entire mechanism to be removed from the chassis, which is a tricky job with all the various PCBs still attached together with flex ribbons.

    In the process of doing this I'd also discovered that the head flex was split (looks like it's been pinched between the case and the back cover in a previous botched repair attempt), and also that the keypad PCB was corroded by battery leakage, with several traces open-circuit. I've repaired both of these by bridging gaps with tiny wires, in some of the most delicate soldering I've ever attempted!

    After a thorough clean, straightening the shell to get the lid catch to lock, and the unit reassembled and working, frustratingly the cassette sounded terrible! Obvious that the azimuth is way off. So I took out the head assembly again, and fully dismantled it to investigate. Bizarrely, I found that someone has stuck a tiny plastic washer under one side of the head mount, which tilts it at an angle and ruins the factory azimuth setting. With this removed and the whole thing reassembled, finally I have respectable sound quality! For a final touch I've 3D-printed it a new battery cover.

    This was by far the most difficult Walkman restoration I've attempted and the most complex model I've ever worked on. It contains at least four PCBs with active components, a couple more if you count the keypad and motor, and about 6 flex ribbons connecting everything together including the head and solenoid. Very satisfying to have brought it this far back to life, and I think worth it considering its rarity. It's still not perfect - my keypad repair is temperamental, the azimuth is slightly off in one direction, and the capstans have some pitting after cleaning off the rust. If I ever find a suitable donor unit I'll try to replace these.

    Interested to hear if anyone else has owned or restored one of these?

    Some photos...

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    autoreverser likes this.
  2. autoreverser

    autoreverser Well-Known Member

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    great job, mate :thumbsup:
     

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