R80/RA81 diagnostic experience?

From: Johnny Billquist <bqt_at_update.uu.se>
Date: Tue Mar 9 07:23:57 2004

On Tue, 9 Mar 2004 Gooijen H <GOOI_at_oce.nl> wrote:

> I am not sure that removing the brake will help.

More likely not. In fact, the break is there for a reason. To stop the
drive when spinning down. Otherwise, it will spin for a long time. I also
suspect that the break is engaged until you try to spin the disk up, so
that the disk don't swing back and forth just because you move the drive

> I once heard the following rumour:
> the brake in combination with the 'heavy' motor
> makes sure that the disk platters always rotate
> in the same direction, never for a short instance
> in the other direction (vibration, power flutter,
> whatever reason). Rotation in the opposite direction,
> for any short moment, will cause the air on which the
> r/w head fly to disappear and result in an immediate
> head crash ...

Are you suggesting that a platter, weighting several kilograms, spinning
at something like 3600 rpm, suddenly can change spin direction at a
millisecond notice?

> As I said, it is a rumour I once heard a few years ago.
> Has anybody heard of this too?

That's one of the more outrageous rumours I've ever heard. :-)
The amount of energy required to do that trick would blow every fuse in
your house, and then some. We're talking about living mass here. Physics,
you know... ;-)

However, vibration can cause a head crash...


Johnny Billquist || "I'm on a bus
                                  || on a psychedelic trip
email: bqt_at_update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
Received on Tue Mar 09 2004 - 07:23:57 GMT

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