Reviving ancient MFM drives (was Re: formatting MFM drives on a IBM PC)

Adrian Stoness tdk.knight at gmail.com
Thu Sep 28 11:40:35 CDT 2017


prolly a failing ic of some sort?


On Thu, Sep 28, 2017 at 11:21 AM, Geoffrey Oltmans via cctalk <
cctalk at classiccmp.org> wrote:

> On Thu, Sep 28, 2017 at 11:17 AM, Al Kossow via cctalk <
> cctalk at classiccmp.org> wrote:
>
> >
> >
> > On 9/28/17 7:38 AM, Mike Stein via cctalk wrote:
> >
> > > What is it that usually fails when the drive can't read the servo info?
> > The data on the platter, or?
> >
> > I've never dug that far into it beyond fiddling with Micropolis trying to
> > mechanically get it to
> > find the servo tracks and calibrate to track 0.
> >
> > One of the problems is schematics and documentation on the servo systems
> > are extremely difficult
> > to get. The little that is on bitsavers is all I've come up with in 25
> > years of searching and there
> > is practically nothing useful elsewhere on the web about fixing servos in
> > old 5" disks.
> >
> > It could be heads, media, positioners, component aging in the analog
> > section, etc etc..
> >
> >
> >
> >
>
> Speaking of.... I've got a couple of old MFM drives (10 and 20 MB of a
> variety whose name and model #'s escape me, I wanna say Tandon, but not
> sure). They seem to work fine when I initially format and partition, but as
> they run for a while, they get more and more unreliable. It seems to be a
> function of how long they've been running for rather than a predictable
> pattern of bad tracks sectors? Are there any good sources of
> troubleshooting info at the controller level for these old drives?
>


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