Re: Reviving ancient MFM drives (was Re: formatting MFM drives on a IBM PC)
On Fri, Sep 29, 2017 at 3:05 AM, Christian Corti via cctalk < cctalk@classiccmp.org> wrote: > On Thu, 28 Sep 2017, Geoffrey Oltmans wrote: > >> 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? >> > > Well, that's normal. The usual procedure is to let the drive warm up for > 10-20 minutes before formatting. And it is also normal for some models that > they must be reformatted after, say, a couple of months or years, depending > on make and manufacturer. The Rhodime 50MB drive in my IBM 8550 is such a > beast. My procedure is to run Norton CALIBRAT to reformat the drive > losslessly. > > > Good idea. I'll give that a shot.
Re: Reviving ancient MFM drives (was Re: formatting MFM drives on a IBM PC)
On Thu, 28 Sep 2017, Geoffrey Oltmans wrote: 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? Well, that's normal. The usual procedure is to let the drive warm up for 10-20 minutes before formatting. And it is also normal for some models that they must be reformatted after, say, a couple of months or years, depending on make and manufacturer. The Rhodime 50MB drive in my IBM 8550 is such a beast. My procedure is to run Norton CALIBRAT to reformat the drive losslessly. Christian
RE: Reviving ancient MFM drives (was Re: formatting MFM drives on a IBM PC)
Old 10 and 20 MB MFM drives are most likely open loop positioning systems which are highly vulnerable to off track due to thermal changes and stiction. They also could have flying height problems due to contamination on the slider. These failure modes can manifest themselves a slow soft problems such as you are describing One thing I would do is format them only after they are warmed up and well exercised and then I would never turn them off. If I did turn them off then I would have a batch file do a bunch of seeks for a minute or so during the boot and if I were really clever find a way to do a seek every 5 minutes or so. Tom -Original Message- From: Adrian Stoness [mailto:tdk.kni...@gmail.com] Sent: Thursday, September 28, 2017 9:41 AM To: Geoffrey Oltmans; General Discussion: On-Topic and Off-Topic Posts Subject: Re: Reviving ancient MFM drives (was Re: formatting MFM drives on a IBM PC) prolly a failing ic of some sort? On Thu, Sep 28, 2017 at 11:21 AM, Geoffrey Oltmans via cctalk < cctalk@classiccmp.org> wrote: > On Thu, Sep 28, 2017 at 11:17 AM, Al Kossow via cctalk < > cctalk@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? >
Re: Reviving ancient MFM drives (was Re: formatting MFM drives on a IBM PC)
prolly a failing ic of some sort? On Thu, Sep 28, 2017 at 11:21 AM, Geoffrey Oltmans via cctalk < cctalk@classiccmp.org> wrote: > On Thu, Sep 28, 2017 at 11:17 AM, Al Kossow via cctalk < > cctalk@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? >
Reviving ancient MFM drives (was Re: formatting MFM drives on a IBM PC)
On Thu, Sep 28, 2017 at 11:17 AM, Al Kossow via cctalk < cctalk@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?
