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Sony WM-7 Restoration

Discussion in 'Tech talk' started by Ken80s, Dec 17, 2016.

  1. Ken80s

    Ken80s Well-Known Member

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    Hi, here I attach the Sony WM-7 Service manual for your reference. Good luck!
     

    Attached Files:

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  2. mihokm

    mihokm Active Member

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    Excellent. Thank you very very much, it helps me a lot.
     
  3. nickeccles

    nickeccles Well-Known Member

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    Tiny tiny motor......I remember being so amazed when I first opened a WM2 in around 1981 - A similar tiny cylinder motor that can turn a cassette :wink:
     
  4. StaticAudio

    StaticAudio Member

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    Thanks Ken80s for this tutorial!
    Can you tell me what size belt you have used in the WM7?
    The service manual only says 'belt' with the partno., but not the size.
     
  5. Ken80s

    Ken80s Well-Known Member

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    Hi StaticAudio, sorry for the delay. In fact I don't really know the correct belt size for WM7, I just use the closest belt that could fit in. Nevertheless, let me find out more information and come back to you soon.
     
  6. Ken80s

    Ken80s Well-Known Member

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  7. doublecee

    doublecee Active Member

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    That would be a belt from Marian, and highly recommended.
     
  8. StaticAudio

    StaticAudio Member

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    Thanks , Ken, I'm going to order one of those!
     
  9. Reimar

    Reimar New Member

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    Hi guys. I was lucky to get a WM-7 for a great price in great condition. Serviced & repaired it today, pretty much just cleaning and replacing the belt. It runs perfectly and I am really happy :) Thank you @Ken80s for the information & service manual!

    IMG_0268.JPG IMG_0267.JPG

    However, in this machine the belt runs in a rather unusual way and is hard to install. You need patience and precision and a little experience. Some things that might help:
    • Consider de-soldering all wires but the flex-cable from the circuit board to easily access the transport mechanism. Make photos, write down everything, keep an eye on the service manual.
    • The belt in my model really melted into sticky black goo. You must clean it all off with alcohol. I prefer precision tooth brushes over q-tips. But work gently, the brushes may spray the alcohol and plastic goo all over the mechanics.
    • During re-assembly, make sure no wire is trapped between the circuit board and chassis, especially where the screws go. Use new tape to hold the cables in place:
    IMG_0254.JPG
    • There is a switch and a lever, make sure to align them correctly. This is pretty much the only thing that could go wrong when re-installing the board.
    IMG_0251.JPG

    • You can adjust the motor speed with a single screw like in most players. However, with the WM-7 you can do this with the lid put back on (which is really nice). Just remove the little plastic plug from the hole in the back lid to access it from the outside:

    IMG_0250.JPG IMG_0255.JPG

    I hope someone may find this useful :)
     
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  10. Reimar

    Reimar New Member

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    Oh – does anyone know where I can get replacement rubber pinch rollers for this model?
     
  11. Boodokhan

    Boodokhan Well-Known Member

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    Thanks @Reimar
    Your recommendations/ guide is really good.
    I am also looking for some pinch roller. I need all different sizes.
     
  12. Ken80s

    Ken80s Well-Known Member

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    Excellent work @Reimar
    Thanks for adding essential information to the WM-7, appreciate the pictures very much. I hope you will enjoy listening to tapes on this unit.
     
  13. Gáb

    Gáb Member

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  14. DX7boy

    DX7boy New Member

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    Mine is humming. It‘s the humming of the Motor and it‘s always there. It gets lost in Hiss if i Turn the Volume up but if i Turn it down to Zero it‘s extremely noticable.

    i changed the 2 C‘s with 220 uF around the Motor but it changed Nothing, May it‘s a Little Bit More quiet than before but could be just imagination. Does anybody Know how to fix it?

    Cheers Tobi
     
  15. Ken80s

    Ken80s Well-Known Member

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    Humming is very likely due to floating ground. Check the wiring of the tape head and also the components soldering points. Possible dry joint, try re-solder also the output jack connector on the board. Plug, unplug and wiggling of the headphones may cause issue to the connector.
     
    Last edited: May 29, 2020
  16. Ken80s

    Ken80s Well-Known Member

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    Over time these plastic gears will wear out causing the teeth to disengage. Try to salvage from other unit if you could find one. This is truly a mechanical problem not so on electronics.
     
    Last edited: May 29, 2020
  17. DX7boy

    DX7boy New Member

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    If it was the Head the humming would depend on the Volume (less Volume, less zum). The humming comes From the Motor. It‘s noticable if Volume is at Zero and Stays the Same Volume no matter how High the Volume is. At some point Tape hiss and Music is louder than the humming so you can‘t Hear it anymore. I‘m sure it‘s a Bad capacitor That disturbs the Audio Output. Typical Humming of the Head would be different.
     
  18. dorenberg

    dorenberg New Member

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    Hi all, looking at this thread, I was wondering the following. I own a WM-7 since Yesterday and ordered a new belt. However, when entering the (non original) headphones the machines keeps reversing FFWD and REV. Is there a solution for this? I know it has something to do with the original remote being not present. But is there a work around for this?
     
  19. Valentin

    Valentin Well-Known Member

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    Are you using a 3-pin or 4-pin jack headphones ? It depends on the impedance of the headphones from what I have investigated in my unit. High impedance triggers the remote control circuit. Tell us what heaphones are you using to make a correct suggestion regarding a solution.
     
  20. dorenberg

    dorenberg New Member

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    I have tried the following.

    Sony noice cancellation headphones wh1000mx2.
    4 pin normal earbuds. Measured 20 ohm
    3 pin over ear headphones (non amplified), measured 15 ohm.
    3 pin normal earbuds (also sony, but from minidisc portable, not measured)
    All 4 do not work. I don't have more in house

    So maybe something else is going on?
     

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