Dead RF31 DSSI Disk.. final Question..

Jarratt RMA robert.jarratt at
Tue May 12 15:31:58 CDT 2015

I can really sympathise with you on the PSU front. I tried to repair one of
these, but it was designed in such a way that it was really hard to get at
the caps to remove them for testing. My problem was that even when I did
get to the big Sprague one I couldn't desolder it, presumably there was a
large track/plane taking all the heat away. In the end I gave that PSU away
(along with another working one) to someone who is much better than me.
Although I don't know if he has fixed it yet.



On 12 May 2015 at 13:33, Holm Tiffe <holm at> wrote:

> Johnny Billquist wrote:
> > On 2015-05-12 11:55, Holm Tiffe wrote:
> > >Ok, the disk passed the tests with ok.
> >
> > Excellent.
> >
> > >I've tried to boot something from DIA0 DIA1 and DIA2..nosurchfile so the
> > >disks seems to be empty.
> >
> > Oh Well...
> >
> > >Now I think about a reformat of the drives, but there is no such
> procedure.
> > >There is an erase program that should rewrite eachs sector with several
> > >patterns. I'll think that it will do the job.
> > >Does an format programm exists "in the field"  or is something like
> thisi
> > >proprietary to DEC?
> >
> > Why would you want to reformat the drives?
> > That said, I would expect such a utility to exist in the firmware of the
> > drive.
> > But normally, since these drives remap bad sectors automatically, you
> > should normally just go on using them, and everything is ok.
> >
> >       Johnny
> The exerciser showed some correctable soft errors, wich is pretty much
> normal I think. Reformating the drive should simply "freshen up" the data
> tracks but erase should do the same in this regard.
> Since the distks aren't containing anything interresting, it would be the
> right time now to do a reformat.
> I think the head assembly has an voice coil engine anyways, so servo tracks
> are needed to do the positioning. It is clear that they aren't affected
> from
> a reformat...
> I've changed some Nippon Chemicon electrolytics from the PSU now. All
> 330µF 25V Caps are bad, an 1000µF 25V too, where other Caps from the same
> company are still ok. I've changed the 330µ Caps against some good Rubycons
> 470µ 25V from which I have "masses".
> The construktor of that H7874 Supply is an dump asshole, no one should ever
> construct switching PSU's in a way that it makes it impossible to desolder
> broken electrolytic Caps! One module with 2 x 330µF Caps is build this way!
> I had to pull of that bad caps, ..brown residues from the electrolyte below
> them on the pcb. Cleaned the PCB with alcohol and soldered the new caps
> from
> above, briged them with an 1206 X7R each.
> Will test the PSU now...
> [..]
> Machine is working now as expected. Currently it is "erasing" the Disk0..
> 53 Minutes...
> Regards,
> Holm
> --
>       Technik Service u. Handel Tiffe,, Holm Tiffe,
>      Freiberger Straße 42, 09600 Oberschöna, USt-Id: DE253710583
>, info at, Fax +49 3731 74200, Mobil: 0172 8790 741

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