Re: Two drives failing.....

[dempson@actrix.gen.nz (David Empson)]

Michael J. Mahon <mjmahon@aol.com> wrote:

> David Empson wrote:
> > <sirghoul@optonline.net> wrote:
> > 
> >> On Tue, 16 Jun 2009 12:20:50 -0700 (PDT), "atfphotography@gmail.com"
> >> <atfphotography@gmail.com> wrote:
> >>
> >>> On Jun 16, 7:07 am, sirgh...@optonline.net wrote:
> >>>> Had something a bit unusual happen last night. Want to make sure I
> >>>> didn't overlook anything.....
> >>>>
> >>>> I have a GS with 4 drives on the smartport. two 3.5", two 5.25".
> >>>>
> >>>> Last night, BOTH 5.25" drives seem to have failed at the same time.
> >>>> Neither will read, although they spin up, and recalibrate fine.
> >>> Sounds like the power supply to me.
> >>>
> >>> Have another one to test with?
> >> Can't see how. everything else, including 3.5" drives work fine.
> > 
> > 5.25" drives might use more power rails than 3.5" drives.
> > 
> > I think 5.25" drives need the -5V rail for part of the read/write
> > circuit (not for spinning the drive or moving the head), but don't have
> > a reference handy to confirm. Both types of drive use +12V for the
> > motors and +5V for the interface logic.
> > 
> > Defintely worth checking the voltages on all your power rails.
> 
> It's the -12v that the 5.12" drives use (you made me wonder if I
> remembered correctly, so I just checked ;-).

Yes, that seems more likely. Thanks for the correction.

I also seem to recall that -12V was only used by the Disk ][, not the
UniDisk 5.25.

-- 
David Empson
dempson@actrix.gen.nz