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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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#1
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Cassette Deck drive bands
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 |
#2
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Cassette Deck drive bands
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 ? |
#3
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Cassette Deck drive bands
On 7/7/2012 4:16 AM, N_Cook wrote:
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 |
#4
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Cassette Deck drive 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. 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. |
#5
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Cassette Deck drive bands
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. |
#6
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Cassette Deck drive bands
William Sommerwerck wrote in message
... 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 ? |
#7
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Cassette Deck drive bands
William Sommerwerck wrote in message
... 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. I hadn't thought of reflective-opto device - will try a diode check |
#8
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Cassette Deck drive bands
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. |
#9
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Cassette Deck drive bands
N_Cook wrote in message
... William Sommerwerck wrote in message ... 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. 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 |
#10
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Cassette Deck drive bands
William Sommerwerck wrote in message
... 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. 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. |
#11
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Cassette Deck drive bands
On Jul 7, 7:23*am, "N_Cook" wrote:
William Sommerwerck wrote in message ... 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 ?- Hide quoted text - - Show quoted text - usually means rotated to lie on its back |
#12
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Cassette Deck drive bands
On Jul 7, 9:18*am, "N_Cook" wrote:
William Sommerwerck wrote in message ... 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. 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.- Hide quoted text - - Show quoted text - Was that in the 1910's or 1920's G.? |
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