how to adjust the staionary control track/mono audio head ?

Discussion in 'Electronic Repair' started by davexnet02, Jan 2, 2005.

  1. davexnet02

    davexnet02 Guest

    Hello all,
    I'm trying to realign this VHS vcr head without any special
    equipment. It has three adjustment screws,each on springs.
    One in the front, to control the front height, and two at
    the back (like a triangular arrangement) to control the
    back height / azimuth angle.

    I don't think it's critical, not using the mono
    sound track.
    A problem I'm observing is the 2 to 3 inches of tape
    between this head, and the rightmost roller guide.

    As the tape is playing, there is not even tension on the tape,
    visible here as an occasional "flap" of the tape on the top edge.
    The bottom edge of the tape is tight but the top is
    comparatively loose.

    Not sure if this due to this heads alignment, or possibly
    a worn switch roller.

    Any tips appreciated.
    Dave
    davexnet02, Jan 2, 2005
    #1
  2. davexnet02

    Guest

    davexnet:
    The A/C head "tilt" adjustment can straighten out the problem you
    described with the apparent slack at the top of the tape; just don't
    over do it; make certain that the tape is smooth at both the top and
    bottom just before it goes past the A/C head.
    And yes, the "pinch roller" (switch roller?) can have a lot to do with
    smooth tape handling and proper running past the A/C head, replace it
    if the A/C head tilt adjustment is not providing proper results.
    electricitym
    =


    davexnet02 wrote:
    > Hello all,
    > I'm trying to realign this VHS vcr head without any special
    > equipment. It has three adjustment screws,each on springs.
    > One in the front, to control the front height, and two at
    > the back (like a triangular arrangement) to control the
    > back height / azimuth angle.
    >
    > I don't think it's critical, not using the mono
    > sound track.
    > A problem I'm observing is the 2 to 3 inches of tape
    > between this head, and the rightmost roller guide.
    >
    > As the tape is playing, there is not even tension on the tape,
    > visible here as an occasional "flap" of the tape on the top edge.
    > The bottom edge of the tape is tight but the top is
    > comparatively loose.
    >
    > Not sure if this due to this heads alignment, or possibly
    > a worn switch roller.
    >
    > Any tips appreciated.
    > Dave
    , Jan 2, 2005
    #2
  3. davexnet02

    Asimov Guest

    "davexnet02" bravely wrote to "All" (02 Jan 05 01:57:24)
    --- on the heady topic of "how to adjust the staionary control track/mono audio head ?"

    da> From: davexnet02 <davexnetzerotwo@hooya!.com>
    da> Xref: aeinews sci.electronics.repair:5552

    da> Hello all,
    da> I'm trying to realign this VHS vcr head without any special
    da> equipment. It has three adjustment screws,each on springs.
    da> One in the front, to control the front height, and two at
    da> the back (like a triangular arrangement) to control the
    da> back height / azimuth angle.

    da> I don't think it's critical, not using the mono
    da> sound track.
    da> A problem I'm observing is the 2 to 3 inches of tape
    da> between this head, and the rightmost roller guide.

    da> As the tape is playing, there is not even tension on the tape,
    da> visible here as an occasional "flap" of the tape on the top edge.
    da> The bottom edge of the tape is tight but the top is
    da> comparatively loose.

    da> Not sure if this due to this heads alignment, or possibly
    da> a worn switch roller.

    da> Any tips appreciated.


    Dave, it's never supposed to ride over the edge, only beside it. The
    AC head isn't supposed to change top or bottom tension but if the tape
    path is wrong then it might. I would suspect wear or an improperly
    sitting load arm. Don't mess with the AC unless you are sure the path
    is good. I bet you will find it to be okay then.

    A*s*i*m*o*v

    .... This message transmitted on 100% recycled photons.
    Asimov, Jan 2, 2005
    #3
  4. davexnet02

    davexnet02 Guest

    On 1 Jan 2005 19:43:02 -0800, wrote:

    >davexnet:
    >The A/C head "tilt" adjustment can straighten out the problem you
    >described with the apparent slack at the top of the tape; just don't
    >over do it; make certain that the tape is smooth at both the top and
    >bottom just before it goes past the A/C head.
    >And yes, the "pinch roller" (switch roller?) can have a lot to do with
    >smooth tape handling and proper running past the A/C head, replace it
    >if the A/C head tilt adjustment is not providing proper results.
    >electricitym

    Thank you for your comments.
    The pinch roller is bad, unfortunately.
    If there's a replacement available for < $20,
    it's worth doing. Otherwise time for a new vcr.
    I'm not sure what the history of sony is regarding
    the vcr quality, but this 1995 unit is cheaply made;
    it will not eject with out holding open the flap.
    Seems to be a bad design..

    If you know of a possible source for the pinch roller,
    please advise.
    Thanks,
    Dave
    davexnet02, Jan 2, 2005
    #4
  5. writes:

    > davexnet:
    > The A/C head "tilt" adjustment can straighten out the problem you
    > described with the apparent slack at the top of the tape; just don't
    > over do it; make certain that the tape is smooth at both the top and
    > bottom just before it goes past the A/C head.
    > And yes, the "pinch roller" (switch roller?) can have a lot to do with
    > smooth tape handling and proper running past the A/C head, replace it
    > if the A/C head tilt adjustment is not providing proper results.
    > electricitym


    If no one messed with the A/C adjustments, they haven't changed on their
    own! First try cleaning the pinch roller very thoroughly. If that seems
    to help, replace it.

    --- sam | Sci.Electronics.Repair FAQ Mirror: http://repairfaq.ece.drexel.edu/
    Repair | Main Table of Contents: http://repairfaq.ece.drexel.edu/REPAIR/
    +Lasers | Sam's Laser FAQ: http://repairfaq.ece.drexel.edu/sam/lasersam.htm
    | Mirror Sites: http://repairfaq.ece.drexel.edu/REPAIR/F_mirror.html

    Note: These links are hopefully temporary until we can sort out the excessive
    traffic on Repairfaq.org.

    Important: Anything sent to the email address in the message header above is
    ignored unless my full name is included in the subject line. Or, you can
    contact me via the Feedback Form in the FAQs.

    > davexnet02 wrote:
    > > Hello all,
    > > I'm trying to realign this VHS vcr head without any special
    > > equipment. It has three adjustment screws,each on springs.
    > > One in the front, to control the front height, and two at
    > > the back (like a triangular arrangement) to control the
    > > back height / azimuth angle.
    > >
    > > I don't think it's critical, not using the mono
    > > sound track.
    > > A problem I'm observing is the 2 to 3 inches of tape
    > > between this head, and the rightmost roller guide.
    > >
    > > As the tape is playing, there is not even tension on the tape,
    > > visible here as an occasional "flap" of the tape on the top edge.
    > > The bottom edge of the tape is tight but the top is
    > > comparatively loose.
    > >
    > > Not sure if this due to this heads alignment, or possibly
    > > a worn switch roller.
    Sam Goldwasser, Jan 2, 2005
    #5
  6. davexnet02

    davexnet02 Guest

    On 02 Jan 2005 10:14:08 -0500, Sam Goldwasser <>
    wrote:

    > writes:
    >If no one messed with the A/C adjustments, they haven't changed on their
    >own!

    Obviously. I'm responsible for it being moved, for reasons that
    are besides the point. I've got it back into a reasonalbe
    position. No tracking problems, and good audio from the mono
    head.

    > First try cleaning the pinch roller very thoroughly. If that seems
    >to help, replace it.

    The pinch roller is shot. I started cleaning it and it's
    crumbling before my eyes.
    Now, the tape is being driven up slightly by this roller,
    resulting in a small tape crease on one of the guides.

    Where can I get a new roller. Any sources?
    I'll call
    http://www.partsolver.com/Default.asp
    It looks like they have a bunch of parts for this model
    (slv-798hf).

    regards,
    Dave
    davexnet02, Jan 2, 2005
    #6
  7. davexnet02

    davexnet02 Guest

    On Saturday, 01 Jan 2005 23:00:00 -500, "Asimov"
    <> wrote:


    >Dave, it's never supposed to ride over the edge, only beside it. The
    >AC head isn't supposed to change top or bottom tension but if the tape
    >path is wrong then it might. I would suspect wear or an improperly
    >sitting load arm. Don't mess with the AC unless you are sure the path
    >is good. I bet you will find it to be okay then.
    >
    >
    >
    >... This message transmitted on 100% recycled photons.

    Hi A*s*i*m*o*v
    thanks for the info.
    Video and hifi audio alignment is perfect, the two roller guides
    that align around the drum have never been moved.

    The main problem I have is actually the rubber pinch roller;
    I'll have to find a replacement (any sources appreciated)
    I seem to have realigned the A/C head to a reasonable accuracy.
    cheers,
    Dave
    davexnet02, Jan 2, 2005
    #7
  8. Dave

    After replacing the pinch roller, assuming you find one,
    then DO set the azimuth accurately for maximum treble
    response when playing a pre-recorded tape in mono lo-fi
    mode. If the azimuth is out, recordings you make will
    sound horrible on other non-hifi machines, and anyway
    you can cause the control pulses to be poorly recorded
    causing yet more problems.

    The tape riding up as you describe is a common symptom
    of a ruined pinch roller.

    Colin (www.colin99.co.uk)

    davexnet02 wrote:

    > On Saturday, 01 Jan 2005 23:00:00 -500, "Asimov"
    > <> wrote:
    >
    >
    >
    >>Dave, it's never supposed to ride over the edge, only beside it. The
    >>AC head isn't supposed to change top or bottom tension but if the tape
    >>path is wrong then it might. I would suspect wear or an improperly
    >>sitting load arm. Don't mess with the AC unless you are sure the path
    >>is good. I bet you will find it to be okay then.
    >>
    >>
    >>
    >>... This message transmitted on 100% recycled photons.

    >
    > Hi A*s*i*m*o*v
    > thanks for the info.
    > Video and hifi audio alignment is perfect, the two roller guides
    > that align around the drum have never been moved.
    >
    > The main problem I have is actually the rubber pinch roller;
    > I'll have to find a replacement (any sources appreciated)
    > I seem to have realigned the A/C head to a reasonable accuracy.
    > cheers,
    > Dave
    Colin McCormick, Jan 3, 2005
    #8
  9. davexnet02

    davexnet02 Guest

    On Mon, 03 Jan 2005 19:56:09 +0000, Colin McCormick
    <> wrote:

    >Dave
    >
    >After replacing the pinch roller, assuming you find one,
    >then DO set the azimuth accurately for maximum treble
    >response when playing a pre-recorded tape in mono lo-fi
    >mode. If the azimuth is out, recordings you make will
    >sound horrible on other non-hifi machines, and anyway
    >you can cause the control pulses to be poorly recorded
    >causing yet more problems.
    >
    >The tape riding up as you describe is a common symptom
    >of a ruined pinch roller.
    >
    > Colin (www.colin99.co.uk)

    Thanks for the info Colin,
    I will indeed endeavor to properly align the azimuth once
    I get the pinch roller replaced.
    I've located it at www.partsolver.com for $20 - could be worse.
    Cheers,
    Dave
    davexnet02, Jan 5, 2005
    #9
  10. davexnet02

    davexnet02 Guest

    On Saturday, 01 Jan 2005 23:00:00 -500, "Asimov"
    <> wrote:

    >"davexnet02" bravely wrote to "All" (02 Jan 05 01:57:24)
    > --- on the heady topic of "how to adjust the staionary control track/mono audio head ?"
    >
    > da> From: davexnet02 <davexnetzerotwo@hooya!.com>
    > da> Xref: aeinews sci.electronics.repair:5552
    >
    > da> Hello all,
    > da> I'm trying to realign this VHS vcr head without any special
    > da> equipment. It has three adjustment screws,each on springs.
    > da> One in the front, to control the front height, and two at
    > da> the back (like a triangular arrangement) to control the
    > da> back height / azimuth angle.
    >

    <snip>
    >
    >Dave, it's never supposed to ride over the edge, only beside it. The
    >AC head isn't supposed to change top or bottom tension but if the tape
    >path is wrong then it might. I would suspect wear or an improperly
    >sitting load arm. Don't mess with the AC unless you are sure the path
    >is good. I bet you will find it to be okay then.
    >
    > A*s*i*m*o*v
    >
    >... This message transmitted on 100% recycled photons.

    Hi A*s*i*m*o*v
    I realigned the A/C as best as I can. I'm observing
    reasonable production of the mono audio track, and
    no obvious control track errors.

    One thing that seems flexible on this head is the absolute height.
    Just made a guess on this; I think I left it slightly higher than it
    was.

    I actually fixed the old rubber pinch roller - at least till I
    can get it replaced. I ended up filing it down with a nail file,
    until the crud was off and it was even as best as I could get it.

    regards,
    Dave
    davexnet02, Jan 8, 2005
    #10

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