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JVC Mini DV camera Tape problem

Discussion in 'Electronic Repair' started by Ulrik Smed, Aug 6, 2008.

  1. Ulrik Smed

    Ulrik Smed Guest

    Hi

    I have a GR-DVL140E that trashes the tape when doing backward picture
    search. It runs OK in normal forward playback. I have had the drive
    disassebled almost completely and re-assembled to fix a problem with the
    back tension arm. I can feel that when it runs in backward search mode, it
    does not break the right tape wheel, so the tape is completely untight. If I
    press it lightly against the tape guide arm to the right of the pinch
    roller, it runs OK. And when I remove the pressure, the tape flaps over the
    top of the arm and crashes because there is no backtension.

    There is only one break at the takeup (right) tape wheel, and this is
    disengaged when it runs backward. It seems it would work it this break was
    engaged to provide backtension, but I don't know if this meant to be so. It
    is a quite strong break, normally used to stop the tape after rewinding, I
    think.
     
  2. Ulrik Smed

    Ulrik Smed Guest

    No MiniDV experts out there?

    I'm really puzzled now, I just tried to fool the drive to think a tape was
    inserted by covering the tape end sensors with my fingers while closing the
    tape compartment. It spins the drum, loads the (not present) tape and makes
    its initial short reverse running as if there was a tape inserted. But now
    the break on the right tape wheel IS activated... :-S If it would just do
    that with a tape inserted too, I'm sure it would work. Trying back and forth
    with tape and no tape gives the same result every time, when a tape is
    present the break is deactiveted and the tape trashes.

    How can it tell the difference between a real tape and me cheating the tape
    end sensors? Of course only one of the tape wheels rotate when there is no
    tape (this stops the drive with a warning on the monitor after a short
    while), but the break is activated even before the capstan moves.
     
  3. Ulrik Smed

    Ulrik Smed Guest

    Heh, replying to my own post once again. :)

    I found the problem! There is a pin that sticks up and releases the breaks
    inside the tape cassette when it loads. This is controlled by the same plate
    that controls the right wheel break. When the pin was loaded by the spring
    inside the cassette, it made the plate hang in a slightly wrong position and
    thereby did not activate the right wheel break. This is why it all worked OK
    without tape.

    I fixed it by milling about a half millimeter off the little pin that moves
    the wheel break away from the wheel, so the break came closer to the wheel.
    This was enough to ensure the break was activated, even with the controlling
    plate in the wrong position. It still deactivates OK, the clearance is just
    a bit smaller than before, no problem here. So now it runs the tape nice and
    tight backwards. :)
     
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