IBM 5120 power question

From: Don Maslin <donm_at_cts.com>
Date: Sat Nov 20 22:18:29 1999

On Sat, 20 Nov 1999, Tony Duell wrote:

> > > Ah... Most 8" drives do have mains-powered induction motors, so the
> > > frequency does matter. I've seen reference to the odd drive with a 24V DC
> > > spindle motor, but I've never seen an actual drive like that (although I
> > > am sure they exist). If the motor 'looks' like a mains motor, has a large
> > > capactor can hung off it, and seems to have mains wiring going to it,
> > > then it's likely to be a mains motor.
> >
> > The only 24V DC spindle motor that comes to mind at the moment was on
> > the Tandon 848-02 DSDD half-height 8" drive, Tony.

I never much cared for those drives, Tony. IIRC, there was no way to
remotely unload the heads from the media. The best that you could do
was to power down the spindle motor. Of course, the problem there was
the finite time for the disk to come up to speed when power was
reapplied.
 
> I seem to remember it was an option on a drive made by a company called
> 'Elcomatic'. I have a couple of the drives (with 240V mains motors) on my
> PC/XT, and I have the service manual _somewhere (but don't ask me to find
> it :-)).
>
> These are full-height drives, same form factor as a SA800 or whatever.
> One other neat feature is that as well as the track0 sensor, there's
> another slotted optoswitch that operates on track 43 and greater. So
> these drives don't need the TG43 signal from the controller, which is
> handy if you're linking them to a PC.
>
> However, IBM (and a few other companies) made their own drives, so it's
> quite possible they did something strange [1]. I could well believe that
> they used drives with 24V motors, for example.

I think that a definitive response to Tim's quiz will be quite
interesting. I do not know of any, personally, but...

                                                 - don
 
> [1] Although not as strange as a Radiogram I have the service sheet for.
> This thing would run off AC or DC mains, and there were 3 valves that
> were only used on DC mains. The radio chassis was a conventional
> 'universal' set (series-string heaters, rectify the mains to get the
> anode supply). You guessed it, the other 3 valves (a couple of 50L6's and
> something that would oscillate) formed a 50Hz PSU for the turntable motor.
>
> -tony
>
>
Received on Sat Nov 20 1999 - 22:18:29 GMT