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JVC PC100 clutch problem

Discussion in 'Tech talk' started by mrn, Jan 25, 2017.

  1. mrn

    mrn Member

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    Hello Everybody.
    I got a question regarding the clutch mechanism of the JVC PC100, which seem to cause the problem of fluctuating band speed. Pls. let me just insert a photo from the audiotechnika-blog for those, who cannot recall what a PC100 is :)
    The tape speed fluctuation is clearly visible from the image below: playback of a constant beep recorded by a TCD5. the image shows the same recording, same tape played on the Sony TCD5 (right halve) and the JVC-PC100 (left halve of the photo).
    You clearly see the effect of the smeared 2500Hz line in case of the JVC :(

    Now, I am afraid, the whole rpm-fluctuation is caused by the clutch of the JVC, which seems to be not only a complicated, 4-part thing, but the whole clutch seem to be under huge pressure all the time, when assmbled. Why I think so? Because the spring is compressed to its limits... and because the tiny bottom part has a much wider hole as the top 2 gears, which - i believe- lets the bottom mini gear tilt to sides as the clutch turns.

    Now the questions come:
    - is this problem known? and if yes, what is the proposed solution to fix the rpm problem?
    - do you think that this clutch is only for FFwd and FRwd finctions, and could be simply closed? the reason I am asking this is because there seem to be a second clutch just above the disassembled clutch on the foto. If the other clutch is really a clutch (I did not touched it yet), then the 1st one might really serve only for fast rwd and fwd.

    thanks in advance for all the comments!
    i am really looking forward to have constant tape speed on this beauty.
     

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