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
around.

> 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

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