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Sony WM-F701C belt path and issue

Discussion in 'Tech talk' started by ebuy05, Oct 13, 2017.

  1. ebuy05

    ebuy05 Member

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    Hello everyone!

    I just installed a new belt (thanks Marian!) on my WM-F701C and I would like to confirm if I installed correctly.

    I used the service manual diagram but it wasn't very clearly explained. I'm not sure if the path is correct as when I press play the reels work on both directions but the tape doesn't play.

    I then removed the tape and pressed play: the correct reel moves fine and always both capstans are moving regardless of the direction (they are spinning in opposite direction from each other!?). As I said, it seems that the reels are moving fine though in play mode, except that one side "plays" (without a cassette) for a few seconds and automatically switches to the other side, which "runs" until I press stop. FF and RW works perfectly (even with the tape in).

    I'm loved this unit as it did sounded great.

    Does anyone have an idea on what could be happening? Or what to investigate further?

    Thanks,
    Ed.

     
  2. buzbox

    buzbox Active Member

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    Found this image so it seems like you've done it correctly.


    belt.jpg
     
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  3. Longman

    Longman Well-Known Member S2G Supporter

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  4. Longman

    Longman Well-Known Member S2G Supporter

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    The capstans should go in opposite directions. Depending on the direction one or the other pinch roller engages.

    What the Walkman does with no tape fitted may not be the same as with a tape in. Sometimes they use they use the rotation of one of the reels to sense when the tape runs out and it is time to stop or reverse.

    Are the heads engaging ?

    By the looks of things you could change the belt without removing any boards. If you did remove the board(s) look for any switches on it which engage with the mechanism (the later mechanisms definitely have them).
     
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  5. ebuy05

    ebuy05 Member

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    Thank you buzbox, the diagram you found re-assured me!

    Longman, the heads are engaging. Even without tape you can sense the headphones turning on right after the heads engage. And I didn't notice any switches besides the ones on the back cover (Dolby and Auto-reverse).

    After fidgeting a bit with the case during many trials with and without tape I got it to work! It seems that that is due to a tiny misalignment with the way you close the door or the way the cassette sits on its playing position: if you force the door down when it is playing seems to work more freely and with a better/appropriate speed.

    At least now I know that the belt is installed correctly and the walkman still works (including its glorious dolby-c and DBB) :D

    What I've done so far:
    1) Cleaned the capstans and pinch rollers;
    2) Replaced the belt;
    3) I lubed the motor shaft with watch oil;
    4) I ordered new pinch rollers as well although the originals still look (and feel) ok. Is there any tutorial on how to replace the pinch rollers?

    Issues remaining now:
    a) Speed: seems to struggle to keep the proper speed. It's very depending on the door/cassette misalignment issue.
    b) Tape direction doesn't work with the cassette in. When I tried changing direction (pressing play during playback) it doesn't work: it "tries" but goes back to playing the original side (>). Without the cassette, it works for about 4 seconds and then stops and goes back to the original direction. RW (which uses the same (<) direction reel, also works for only 4 seconds. I have no clue why it works without the cassette for a few seconds!

    Any further suggestions to fix these?

    On a maintenance note: how should I lube the capstans bearing? I was afraid to make a mess and have oil on the shafts. I have a syringe with 0.3mm tip and the watch oil.

    Thanks again!
     
  6. bub

    bub Active Member

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    Models like these are dependent on the door and hinge working properly. Drop it once, misalign the chassis to head block and it's knocked out of whack. This is probably the reason for your speed and reverse issues as you've pointed out. Capstan is probably not making proper contact with the pinch roller.
    Try the following:

    The 701C series has a very delicate lid lock that can be difficult to reassemble properly- ensure that the screw and nut is seated in properly.
    Check if there's too much play in the hinge, or if it is broken.
    The door must sit nearly perfectly flat with little play when closed. If otherwise, your chassis/door is tweaked.

    The reason why REW/REV only works for a few seconds is that the other reel is the one that detects movement via photosensor, if the unit does not detect movement on that reel it thinks that the tape has stopped and reverses or stops.
     
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  7. ebuy05

    ebuy05 Member

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    Hello again, bub.

    I removed and re-installed the lid lock (the one with the spring) and it seems to have gotten slightly better. The door now is actually closing, but I need to pull the lever to the "open" position while closing the door to lock it in place. It is playing right away now, but slower. When I force the door upwards (on the right hand side mostly) the tape speed is corrected and sound is great! It must be a small door misalignment internally that I will need to investigate further. Externally it looks perfect though, the unit seems to have never being dropped (no marks on the corner).

    As for the photosensor causing the RW to stop, any ideas on what could be done to correct this? And is this issue related to the fact that other direction doesn't work?

    Thanks once more,
    Ed.
     
  8. bub

    bub Active Member

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    The photosensor is normal behavior with no tape in it. Other direction not working might be a cam/solenoid/A B detect switch issue, and is a little harder to troubleshoot.
    Does the unit go in REV direction with no tape? Run with the cover off and observe.
     
  9. ebuy05

    ebuy05 Member

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    Hi bub,

    Yes, with no tape it works for about 4 seconds then stops completely.. :(
     
  10. bub

    bub Active Member

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    That's normal.
     
  11. ebuy05

    ebuy05 Member

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    Thanks again, bub!

    So, why when the motor is "loaded" (with the tape in) the RW only "tries" to rewind (no reels spin occurs whatsoever) and then it switches to the play the other side? I'm puzzled :knockout:
     

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