Anyone know how this works? Is there a sensor that recognizes the
transparent bits at the beginning and the end of a VCR tape?

I have two Sony VCRs that upon rewinding come to a crashing halt
rather than a smooth stop.

Thanks for any advice/suggestions.

Art Deco wrote:

Anyone know how this works? Is there a sensor that recognizes the
transparent bits at the beginning and the end of a VCR tape?

I have two Sony VCRs that upon rewinding come to a crashing halt
rather than a smooth stop.

VHS VCR's use the transparent tape at each end. Old style VCR's used a light
bulbs and photocell. Newer ones most likley use an LED and some sort of
photosensor. It should not be hard to find, it would be the only part
that the tape goes through instead of over or around.

Geoff.


--
Geoffrey S. Mendelson, Jerusalem, Israel N3OWJ/4X1GM
IL Voice: (07)-7424-1667 IL Fax: 972-2-648-1443 U.S. Voice: 1-215-821-1838
Visit my 'blog at http://geoffstechno.livejournal.com/

"Art Deco" wrote in message
...

Anyone know how this works? Is there a sensor that recognizes the
transparent bits at the beginning and the end of a VCR tape?

I have two Sony VCRs that upon rewinding come to a crashing halt
rather than a smooth stop.

Thanks for any advice/suggestions.


If you look at the bottom of a VHS cassette, there's a hole near the flap
halfway between the spools. The hole is for the "light tower" which is a
plastic pillar with a LED (or bulb in older models) at the top. If you press
the latch at the side of the cassette so you can lift the flap, this will
expose a tiny slot at each end, there is usually a photo-diode at each side
of the deck lift in the VCR.

In older VCRs bulb failure was fairly common which was usually sensed by the
microcontroller and caused the VCR to refuse to operate rather than work but
fail to slow at the end of the tape. Most modern VCRs use the sensors under
the spool drives to calculate the ratio of tape on the two spools and cut to
a slower speed as it nears the end of the tape. If your lucky its these
sensors causing the problem and they're opto-reflective types with just some
dust to clean off - if they're Hall effect sensors you probably have a MPU
fault!

In article , "I.F." wrote:

"Art Deco" wrote in message
.. .

Anyone know how this works? Is there a sensor that recognizes the
transparent bits at the beginning and the end of a VCR tape?

I have two Sony VCRs that upon rewinding come to a crashing halt
rather than a smooth stop.

Thanks for any advice/suggestions.


If you look at the bottom of a VHS cassette, there's a hole near the flap
halfway between the spools. The hole is for the "light tower" which is a
plastic pillar with a LED (or bulb in older models) at the top. If you press
the latch at the side of the cassette so you can lift the flap, this will
expose a tiny slot at each end, there is usually a photo-diode at each side
of the deck lift in the VCR.

In older VCRs bulb failure was fairly common which was usually sensed by the
microcontroller and caused the VCR to refuse to operate rather than work but
fail to slow at the end of the tape. Most modern VCRs use the sensors under
the spool drives to calculate the ratio of tape on the two spools and cut to
a slower speed as it nears the end of the tape. If your lucky its these
sensors causing the problem and they're opto-reflective types with just some
dust to clean off - if they're Hall effect sensors you probably have a MPU
fault!

Most should have speed sensors if a high speed rewind system is employed.
This is in addition to the regular sensors. Its got to slow down before the sensor
is set off or else banged tape or something bad.

greg