1 Feb
1999
1 Feb
'99
5:19 a.m.
Is anyone on the List, in the Southern California area, interested in a
CDC 9766 350MP top loader, with three disk packs? This unit was attached
to the Prime system I got recently, but is *not* going to be used with
the way I have the Prime configured.
I have gotten an offer of $100, but I have to deliver the damn thing,
and it's 600lbs.
I would like to sell this unit for a little more than $100, or I would
consider donating it to a worthy situation, ie. needed for a systems
restoration, or to supply parts made of Unobtanium.
Replies by e-mail....
Cheerz
John
1 Feb
1 Feb
6:44 a.m.
John Lawson <jpl15(a)netcom.com> wrote:
Is anyone on the List, in the Southern California
area, interested in a
CDC 9766 350MP top loader, with three disk packs? This unit was attached
This drive is equivalent to (and pack-interchangeable with) the DEC RM05,
but it is not electrically interchangeable with the DEC drive. DEC had
CDC customize the drive interface for use in the RM05.
It NEEDS three-phase power, and a fair amount of it, to run the AC
synchronous spindle motor. This is not something that can easily be
converted to run on single-phase, so don't get the idea that you can
run it in your house or garage.
But they are great drives, and it would be a shame for them to be scrapped.
Eric
8:08 a.m.
On 1 Feb 1999, Eric Smith wrote:
John Lawson <jpl15(a)netcom.com> wrote:
> Is anyone on the List, in the Southern California area, interested in a
(snip)
It NEEDS three-phase power, and a fair amount of it, to run the AC
synchronous spindle motor. This is not something that can easily be
converted to run on single-phase, so don't get the idea that you can
run it in your house or garage. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Ayyy! Sez 'oo?
While single-to-three-phase converters are not normally household
items, they exist and are usefull for such endeavors. The ones in my
shop have the added bonus of being variable speed/torque/inrush ....
handy for starting up long-dormant machinery.
But it is a trivial matter to run any three-pahse motor from
single phase... one uses capacitors to shift the phases of the
windings in proper relationship. It takes a knowledge of R/C
networks and a good AC ammeter to finely balance the currents in the
leads, but it can be done for the price of the caps. If one has
access to a large surplus or appliance salvage yard, so much the
better. I have run several machines this way.
The drawbacks are: it's grossly inefficient
starting torque is low
careful 'tuning' is required for proper sync.
But they are great drives, and it would be a shame for
them to be scrapped.
I'd rather not sell this one (though the offer was from a company
who maintains and re-builds them... so at least the cadaver would be
used to keep other drives alive) but it's taking up precious room
and it's *heavy*.
Eric
Thanks for the amplifying info... I did not know the RM05 was
mechanically similar.
Cheerz
John
9:23 a.m.
I wrote:
so don't get the idea that you can
run it in your house or garage.
John Lawson <jpl15(a)netcom.com> replied:
Ayyy! Sez 'oo?
[...]
But it is a trivial matter to run any three-pahse
motor from
single phase... one uses capacitors to shift the phases of the
windings in proper relationship. It takes a knowledge of R/C
networks and a good AC ammeter to finely balance the currents in the
leads, but it can be done for the price of the caps. If one has
access to a large surplus or appliance salvage yard, so much the
better. I have run several machines this way.
Have you actually run a 9766 or another comparable drive that way?
Everybody talks about doing it, but I've never yet heard any documented
case of it being done for a removable-pack disk drive using an AC
synchronous spindle motor.
I'll believe it when there's a documented case of it being done, and
working successfully. Until then, I'll stand by my claim.
Cheers,
Eric
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