WM-101 DC to DC Convertor Problem

Discussion in 'Tech talk' started by Stereo, Nov 19, 2023.

  1. Stereo

    Stereo New Member

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    Got a Sony WM-101 which won't play tapes as the motor wont spin. Upon examination the problem seems to be with the DC to DC converter as I am not getting 2.8V at the test point when play is engaged. I have replaced the output capacitor and cleaned the leaf switches with contact cleaner. I have noticed that the walkman's voltage drops to around 0.5V when play is engaged and the DC test point is 0.2V then drops to 0V. Has anyone come across this before and have any ideas ?
     
  2. Valentin

    Valentin Well-Known Member

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    The leaf switches on these units usually need to be cleaned with sandpaper (800-1000 grit), contact cleaner alone usually doesn't do it.
    I would do this first and see what happens. The fact voltage drops under load would point in the direction of increased contact resistance.

    @Mister X Please move this to the walkmans section.
     
  3. Stereo

    Stereo New Member

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    Thanks Valentin for the advice I cleaned the leaf switch with 1000grit sandpaper, unfortunately the motor still wont spin. I now noticed when play is engaged the Walkman's voltage now drops to around 0.2 V when play is disengaged the the Walkman's voltage very slowly starts to climb back up to 1.5 V. Could another component be responsible for this Voltage drop e.g. inductor or the transformer ? I have already replaced the electrolytic capacitor C804.

    IMG_20231120_195620.jpg
    Screenshot_20231120-195011.jpg
     
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  4. Stereo

    Stereo New Member

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    Got the motor to spin happy days, the problem was with the capacitor in the battery box.
     
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