----- Original Message ----- From: "Al Kossow via cctalk" <cctalk@classiccmp.org> To: <cctalk@classiccmp.org> Sent: Thursday, September 28, 2017 12:17 PM Subject: Re: formatting MFM drives on a IBM PC
> > > 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.. > ------------- Too bad. I'm probably not the only one who has drives that sound fine (i.e. no bad bearings, scratched surfaces etc.) but will not initialize; they twitch back and forth on startup, presumably looking for track 0, and then give up. Seems like a shame to scrap them if only there were some remedy... m
