Capstans never stop spinning in JVC cassette decks?
David G Metzger
a JVC TD-V661 noticed that the capstans never stop spinning, or at least
they spin while the cassette bay is open and there is no tape in there.
I couldn't see well enough through the bay window to determine if the
capstans stopped spinning after the bay door is closed.
Although I am sure that the capstan motor and bearings are designed
for a long life, this would seem to promote unecessary wear. Anyone care
to speculate why it's designed this way?
--
Dave Metzger
d...@shell.portal.com
James M. VandeVegt
: I've recently been looking at cassette decks, and while examining
My JVC TD-V541 is the same way. I verified (by taking off the removable
part of the cassette door) that they always run when the power switch
is on. I guess they wanted to cut back on switches. Poor design
if you ask me.
--
| James M. VandeVegt | University of Nebraska--Lincoln |
| vand...@cse.unl.edu | Computer Science and Engineering |
--------------------------|================================================|
| #include <disclaimer.h> | Sales tax on mail order: Just Say NO! |
Spaceman Spiff
Metzger) wrote:
>
> I've recently been looking at cassette decks, and while examining
> a JVC TD-V661 noticed that the capstans never stop spinning, or at least
> they spin while the cassette bay is open and there is no tape in there.
> I couldn't see well enough through the bay window to determine if the
> capstans stopped spinning after the bay door is closed.
>
ear pretty close to the unit, you can hear the hum of the motors.
> Although I am sure that the capstan motor and bearings are designed
> for a long life, this would seem to promote unecessary wear. Anyone care
> to speculate why it's designed this way?
>
Another reason why I settled for the Aiwa ADF-810. This deck starts its
motors
only when it needs to move the tape. I don't have to worry about the motors
giving out if I go off for a weekend and forget to switch off the deck.
However, I have noticed that even the Nakamichi decks keep their capstans
active although there's no tape activity. A salesman I talked to about why
some decks did this gave me some bullshit (not surprising) about keeping
the
motors warm :-)
The only pro that I can attribute to continuously spinning capstans is that
they are easier to clean.
Go for the Aiwa. Rock solid design, and great sound for the price. It even
has a remote. One minor complaint is that its mechanism is a bit noisy when
it moves the playback head assembly. But I have managed to live with that.
Sundar Prasad
University of BC
Vancouver, Canada
Mark Biegler
>David G Metzger (d...@shell.portal.com) wrote:
>: I've recently been looking at cassette decks, and while examining
>: a JVC TD-V661 noticed that the capstans never stop spinning, or at least
>: they spin while the cassette bay is open and there is no tape in there.
>: I couldn't see well enough through the bay window to determine if the
>: capstans stopped spinning after the bay door is closed.
>: Although I am sure that the capstan motor and bearings are designed
>: for a long life, this would seem to promote unecessary wear. Anyone care
>: to speculate why it's designed this way?
>
>My JVC TD-V541 is the same way. I verified (by taking off the removable
>part of the cassette door) that they always run when the power switch
>is on. I guess they wanted to cut back on switches. Poor design
>if you ask me.
My Yamaha KX-670 is the same way. Poor design? I don't know... I hope
not. Perhaps it has something to do with "full logic transport"?
I'm just guessing as my other (much older) decks don't do this.
- Mark
--
Mark Biegler (VE5MPB) bie...@cs.uregina.ca
Department of Computer Science W: (306) 585-4110
University of Regina H: (306) 522-1770
Regina, Saskatchewan Canada S4S 0A2 Office: CW 307.12
Ralph Christopher Slate
>>: I've recently been looking at cassette decks, and while examining
>>: a JVC TD-V661 noticed that the capstans never stop spinning, or at least
>>: they spin while the cassette bay is open and there is no tape in there.
>>: I couldn't see well enough through the bay window to determine if the
>>: capstans stopped spinning after the bay door is closed.
>>: Although I am sure that the capstan motor and bearings are designed
>>: for a long life, this would seem to promote unecessary wear. Anyone care
>>: to speculate why it's designed this way?
>>
I'll speculate. It always seemed to me that the higher-end models had the
capstains constantly spinning, while the cheapo models don't. I'll
guess that it's a planned feature (although I can't imagine why).
Perhaps (like someone said) it's to reduce the shock from starting
and stopping?
Ralph
sla...@rpi.edu
Jamie Hanrahan, Kernel Mode Systems
It would take extra mechanics, moving parts, etc., to disengage the capstan
from the motor, and that would mean additional chances for flutter and other
problems, and those extra parts would wear a lot worse than the capstan
bearings do now (since they'd have to move a lot to engage and disengate the
capstan drive).
Given almost any reasonable design for the capstan bearings, wear should not be
a problem in them. You'll wear the heads out first.
--- Jamie Hanrahan, Kernel Mode Systems, San Diego CA
Internet: j...@cmkrnl.com (JH645) Uucp: uunet!cmkrnl!jeh CompuServe: 74140,2055
George Jefferson
:not. Perhaps it has something to do with "full logic transport"?
my old and pretty cheap 'full logic' deck doesn't run the capstan
all the time.
I'd think the nicest thing to do to the motor would be to run
it continuously, then shut it down after some period of inactivity.
See if they don't shut down after 20 minutes or so.
--
george -- geo...@mech.seas.upenn.edu
Werner Ogiers
: In article <2ra10p$m...@news1.svc.portal.com>, d...@shell.portal.com (David G
: Metzger) wrote:
: However, I have noticed that even the Nakamichi decks keep their capstans
: active although there's no tape activity. A salesman I talked to about why
My Naks don't (CR-2, 550). But the CR-2 keeps the control motor spinning.
Not a problem, as it is easy to replace when it dies, since it is not
included in the actual tape transport.
: Go for the Aiwa. Rock solid design, and great sound for the price. It even
: has a remote. One minor complaint is that its mechanism is a bit noisy when
: it moves the playback head assembly. But I have managed to live with that.
That's a bit typical for 2-motor transports. Nothing to worry about.
--
Werner Ogiers IMEC, division MAP
phone: +32 16 281 556 Kapeldreef 75
fax: +32 16 281 508 B-3001 Leuven
e-mail: ogi...@imec.be Belgium
--------------------------------------------------------------------------------
You may think this is science-fiction, cyberpunk. But it's not. It's real.
--------------------------------------------------------------------------------
rsan...@alb.asctmd.com
circuitry to do motor control was probably thought to be too expensive for the
price class. Or it was overlooked during the design or the project engineer
made the decision for some other reason.
Also, if the deck has heads other than perma-alloy, the motor or capstan
bearings will wear out long before the head.
In general, keeping the motor/capstan running while the tape is not engaged
in a paused mode is a poor design. Denon, as an example does not do this.
Bob
David G Metzger
Jamie Hanrahan, Kernel Mode Systems <j...@cmkrnl.com> wrote:
>In article <2ra10p$m...@news1.svc.portal.com>, d...@shell.portal.com
>(David G Metzger) writes:
>> Although I am sure that the capstan motor and bearings are designed
>> for a long life, this would seem to promote unecessary wear. Anyone care
>> to speculate why it's designed this way?
>
>It would take extra mechanics, moving parts, etc., to disengage the capstan
>from the motor, and that would mean additional chances for flutter and other
Why bother disengaging the motor from the capstan when all you have to
do is turn the motor off?
>problems, and those extra parts would wear a lot worse than the capstan
>bearings do now (since they'd have to move a lot to engage and disengate the
>capstan drive).
>
>Given almost any reasonable design for the capstan bearings, wear should not be
>a problem in them. You'll wear the heads out first.
>
> --- Jamie Hanrahan, Kernel Mode Systems, San Diego CA
>Internet: j...@cmkrnl.com (JH645) Uucp: uunet!cmkrnl!jeh CompuServe: 74140,2055
--
Dave Metzger
d...@shell.portal.com
CC01...@brownvm.brown.edu
> In general, keeping the motor/capstan running while the tape
> is not engaged in a paused mode is a poor design. Denon, as an
> example does not do this.
> Bob
Denon, as an example, *does* this.
John
Pedro Baltazar Valconcelos
: My JVC TD-V541 is the same way. I verified (by taking off the removable
: part of the cassette door) that they always run when the power switch
: is on. I guess they wanted to cut back on switches. Poor design
: if you ask me.
My Sony TCK611S works exactly the same way, so does a friend's
Technics deck --- I don't think its poor design, its just that the
capstans motors should be rotating at a very tight tolerance, and
it avoids having to switch them on & off. Also, I don't know what
should wear them sonner, the constant rotating or constantly switching
them on & off. Anyway, you can do as do: don't have your deck turned on
if you're not listening or recording with it...
--
Pedro Vasconcelos email: p...@ncc.up.pt
Centro de Informatica da Universidade do Porto
PORTO - PORTUGAL
===========================================================
"What has eight legs and flies?
--- A string quartet on a foreign tour."
Peter Chrzanowski
David G Metzger (d...@shell.portal.com) wrote:
: I've recently been looking at cassette decks, and while examining
: a JVC TD-V661 noticed that the capstans never stop spinning, or at least
: they spin while the cassette bay is open and there is no tape in there.
: I couldn't see well enough through the bay window to determine if the
: capstans stopped spinning after the bay door is closed.
: Although I am sure that the capstan motor and bearings are designed
: for a long life, this would seem to promote unecessary wear. Anyone care
: to speculate why it's designed this way?
In article <2ran04$8...@crcnis1.unl.edu>, vand...@cse.unl.edu (James M. VandeVegt) writes:
> My JVC TD-V541 is the same way. I verified (by taking off the removable
> part of the cassette door) that they always run when the power switch
> is on. I guess they wanted to cut back on switches. Poor design
> if you ask me.
When my Pioneer tape deck died during a thunderstorm I discovered
that (1) the bridge rectifier had shorted, and (2) the power
transformer primary was open. The tape deck was not turned on
during the storm, nor did it take anything like a direct hit.
Further investigation revealed that the "power switch" on the front
panel only disconnected the low-voltage DC; that is, it was designed
so that its power supply was *always* connected to the AC line
even when turned off. And, although it was labelled as being
U.L. and C.S.A. approved, there was no fuse visible anywhere.
I'm inclined to conclude (1) the manufacturer connected the power
switch to the low-voltage DC side because that cost a bit less than
using a switch rated for 120VAC, and (2) the "fuse" was a bit of
fuse wire inside the power transformer -- which adequately protects
against fire, but means the transformer must be replaced when the
fuse blows.
The transformer has been "backordered" for some time now, and I don't
expect I'll ever see it.
I realize there's a whole industry busy redefining "quality" to mean
"quality is whatever sells" (i.e., quality is defined by the customer).
But, even though this product looks nice and worked reasonably well
(during its short life), this is the sort of "quality" that used to
be called "cheap junk."
Graeme Gill
>I'll speculate. It always seemed to me that the higher-end models had the
>capstains constantly spinning, while the cheapo models don't. I'll
>guess that it's a planned feature (although I can't imagine why).
>Perhaps (like someone said) it's to reduce the shock from starting
>and stopping?
Good quality tape transports are designed to run the tape
at a constant speed, not accelerate and decelerate in the
minimum amount of time. (If you want that as well, expect
to pay 2 to 3 times the price for the transport) The best way
of filtering out high frequency (mechanical) variations is
to have a high rotating mass (yes, even with direct drive
motors). The bigger the mass, the harder it is to start and
stop.
The brass bearings used for these applications are
very reliable and long lasting at the rotational
speeds involved.
Cheap decks have smaller flywheels and simpler DC motors
that are easy to switch on and off. Owners of cheaper
decks are also less demanding of instant response when
they press the play button.
Graeme Gill.
rsan...@alb.asctmd.com
>Denon, as an example, *does* this.
John,
My Denon does not keep the capstans turning when the tape is not engaged. Of
course, the lesser two head models may do this, but mine only turn when playing
or recording a tape, during pause mode, and during fast wind modes.
Bob
CC01...@brownvm.brown.edu
>My Denon does not keep the capstans turning when the tape is not
>engaged. Of course, the lesser two head models may do this, but
>mine only turn when playing or recording a tape, during pause mode,
>and during fast wind modes.
Sorry for this but you are making claims about Denon decks that
are simply not true. I have the service manuals to a few Denons
and *all* the *three* headed decks have const. spinning capstans [CSC].
I.e. Denon uses both methods.
Why is it that you surmise it is the "lesser" models that use
CSC ? In my experience with mass market decks, it is the top
models that use this system. With large flywheels and limited
motor torque, it's almost a necessecity.
John