Cassette Deck drive bands

[N_Cook]

I still regularly replace them for people (tends to be with silicone rubber
bands )
This week something I did not know - found while trying to make sense of
strobing a capstan to set the motor speed. An Aiwa with rotatatable head for
playing the "reverse" side of the tape. Spindle to one capstan was 1.49mm
diameter and the other 1.69mm and proportional size difference to the
capstans, driven by the same band. I'd measured one spindle and then marked
,for strobing, the other capstan. Both decks , Rec/Play & play ,this same
mechanical disparity

 

[N_Cook]

Another oddity with this 1992 Aiwa AD WX888 - end of tape sensor. Instead of
a follower that moves with increase of tension in the tape. This uses the
same small holes in the cassette but is a fixed lump of plastic with 3 wires
coming from it, not coils. Capacitively somehow sensing motion or change in
capacitance of ferrite tape to leader transistion ?

 

[Tim Schwartz]

I still regularly replace them for people (tends to be with silicone rubber
bands )
This week something I did not know - found while trying to make sense of
strobing a capstan to set the motor speed. An Aiwa with rotatatable head for
playing the "reverse" side of the tape. Spindle to one capstan was 1.49mm
diameter and the other 1.69mm and proportional size difference to the
capstans, driven by the same band. I'd measured one spindle and then marked
,for strobing, the other capstan. Both decks , Rec/Play & play ,this same
mechanical disparity

Are the flywheels that the motor belt goes around different diameters?

Regards,
Tim Schwartz
Bristol electronics

 

[William Sommerwerck]

This week something I did not know -- found while

trying to make sense of strobing a capstan to set
the motor speed. An Aiwa with rotatatable head for
playing the "reverse" side of the tape. Spindle to one
capstan was 1.49mm diameter and the other 1.69mm.
There is a proportional size difference to the capstans,
[sic] driven by the same band.

What you mean is that the diameter of the "flange" (or whatever) at the base
of the capstan, which is driven by the same belt, varies so that each
capstan moves the tape at the same linear speed.

If the tape is driven by both capstans at the same time (and I assume it
is), then one capstan is designed to turn ever-so-slightly faster so that
the tape is held under tension.

It's not clear what happens when the tape reverses direction. However, my
Nakamichi used this system, and the tape didn't go spilling into the deck's
innards when it was reversed.

 

[William Sommerwerck]

Another oddity with this 1992 Aiwa AD WX888 - end of tape sensor. Instead
of

a follower that moves with increase of tension in the tape. This uses the
same small holes in the cassette but is a fixed lump of plastic with 3 wires
coming from it, not coils. Capacitively somehow sensing motion or change in
capacitance of ferrite tape to leader transistion ?

Light, probably. The leader reflects more light than the tape.

I've never heard of ferrite-coated tapes.

 

[N_Cook]

This week something I did not know -- found while
trying to make sense of strobing a capstan to set
the motor speed. An Aiwa with rotatatable head for
playing the "reverse" side of the tape. Spindle to one
capstan was 1.49mm diameter and the other 1.69mm.
There is a proportional size difference to the capstans,
[sic] driven by the same band.

What you mean is that the diameter of the "flange" (or whatever) at the base
of the capstan, which is driven by the same belt, varies so that each
capstan moves the tape at the same linear speed.

If the tape is driven by both capstans at the same time (and I assume it
is), then one capstan is designed to turn ever-so-slightly faster so that
the tape is held under tension.

It's not clear what happens when the tape reverses direction. However, my
Nakamichi used this system, and the tape didn't go spilling into the deck's
innards when it was reversed.

I wouldn't say it was a slight difference as in the ratio of 1.49 to 1.69
but not such a large difference I had noticed in general handling.
Probably specious accuracy as I did not remove them for good perpendicular
measurement but 44.86mm and 48.79mm of the capstan flanges. Figure-of-S
shape for the band between the flanges, opposite rotational distrection,
only one engaged pinch-wheel at a time of course. .

By ythe way does the USA term for say the Lazy-S ranch mean an S that is
stretched out or "laid on its back" ie turned through 90 degrees? or both ?

 

[N_Cook]

Instead

Light, probably. The leader reflects more light than the tape.

I've never heard of ferrite-coated tapes.

I hadn't thought of reflective-opto device - will try a diode check

 

[William Sommerwerck]

I wouldn't say it was a slight difference as in the ratio

of 1.49 to 1.69 but not such a large difference I had
noticed in general handling. Probably specious accuracy
as I did not remove them for good perpendicular
measurement but 44.86mm and 48.79mm of the capstan
flanges. Figure-of-S shape for the band between the flanges,
opposite rotational distrection, only one engaged pinch-wheel
at a time of course.

Well, that kind of kills my theory. Your original post indicated that this
was a dual-capstan drive. It isn't.

By the way, does the US term for say the Lazy-S ranch
mean an S that is stretched out or "laid on its back", ie
turned through 90 degrees? or both ?

In cowboy parlance, it means "lying on its side". It does not refer to the
shape or aspect ratio.

 

[N_Cook]

I hadn't thought of reflective-opto device - will try a diode check

Probly diode and photo-resistor, diode on DVM and varying ohmage on another
pair of wires, on varying the ambient light . So would only detect leader
join, not active in the case of a tape jam

 

[N_Cook]

Well, that kind of kills my theory. Your original post indicated that this
was a dual-capstan drive. It isn't.



In cowboy parlance, it means "lying on its side". It does not refer to the
shape or aspect ratio.

Which implies ranch-hands could at least recognise letters.
Pictoral pub signs like the Red Lion or the King's Head started in Britain
because of total illiteracy amongst a lot of the populace.