Re: Transporting a Profile Drive from Helmut Dr. Post on 2012-01-12 (lisalist1)

From: Helmut Dr. Post <helmut_post_at_email.domain.hidden>
Date: Thu, 12 Jan 2012 13:28:48 +0100

Some interesting points to mention here:

Am 12.01.2012 um 02:14 snhirsch wrote:

> On Jan 11, 7:27 pm, Terry Stewart <te..._at_email.domain.hidden> wrote:
>

>> Ok this is where it gets interesting.  The seller has popped the hood and
>> there is a Segate 412 (10MB) drive sitting inside.  Someone has replaced
>> the original Profile drive, yes?

>
> >>No, not necessarily. The ProFile did use a mechanism labeled as
> >>>'ST412', but with a different version identifier string. The label on
> >>>the side of the Apple HDA assembly will say "MLC3.9" after the serial
> number on the Apple variant. Patrick claims (and I have no reason to
> doubt him) that the stepper motor has a finer pitch than the vanilla
> ST412 and requires two pulses to step from track to track.

The only difference between the Apple,version and the PC ST412 is the different stepper motor. There is no special Apple version....
>

>> >I see from Patrick's IDEFIle site that people did replace these drives with
>> >a Segate 412.  I might even have a spare one sitting at home?

>
> >From experience, you cannot replace the drive in a 10M Profile with a
> >regular ST412 - it will slam itself into the limit for about half the
> >formatting run as it runs out of tracks.

But you can replace the PC style stepper motor with the "Apple HD" stepper motor - I have done this many times in a clean room.

>> Let's assume the drive in there is broken.  Assuming it is and my drive at
>> home is ok, how easy is it to instal a bog standard (spare) Segate 412.
>> Is it just a case of low-level formatting it in a PC, then wiring it up to
>> the Lisa and using some Lisa Office installation disks to format and
>> install?

>
> >>>>>Again, I have never been successful (nor do I think anyone has) in
> >>>>replacing the 10M mechanism. If the Z8 microcontroller is a
> >>>"piggyback" ROM version, you can replace the firmware with the 5M
> EPROM and format an ST412 to 5MB (wasting every other track). I've
> ressurrected a couple of 5M drives, so I know it works. If the Z8 is
> a masked-ROM variant, pickup a piggyback version on eBay and give a
> yell. Someone may know where the software is.
>

I have done the replacement many times and I now have some experience to perform this "stepper motor transplant" to change a PC ST412 mechanism into an fully functional Apple ST 412.

> Until recently, it possible to low-level format only on an Apple ///,
> but Al Kossow put a bunch of new software on bitsavers that includes
> (I think) the Lisa-based formatter. I have no experience with this,
> so you'll be blazing new territory :-).
>
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