PDP11 adventures

Curtis H. Wilbar Jr. rescue at hawkmountain.net
Thu Dec 7 23:00:28 CST 2006

Seth J. Morabito wrote:
> On Thu, Dec 07, 2006 at 07:20:05PM +0000, Adrian Graham wrote:
>> On 6/12/06 22:27, "Gordon JC Pearce" <gordon at gjcp.net> wrote:
>>>> Indeed, it looks like the original boot drive (also an RD53) long gave up
>>>> the ghost, which is a shame because it had RT11 5.4 and one of the systems I
>>>> wrote in the 1980's......
>>> What actually fails in them?
>> Head actuator I think; it powers up and spins up, doesn't sound headcrashed
>> but I can't hear or feel the heads move.....
> Definitely check for stiction, it's a very common problem on RD53s.  If
> the data on them is worth saving, you can probably make a clean enough
> environment in your home or office to open up the drive assembly and
> nudge the head loose from the sticky rubber that it's parked against.
> You can probably get at least one good read out of it without it
> crashing (I know folks who've opened up their RD53s, reassembled them,
> and run them successfully for months afterward.  YMMV!)

gah... I should have read beyond 'check for stiction'... the sticktion 
you describe
is what I laid out in option 2... oops... its late... shouldn't be 
reading e-mail...
so I didn't read beyond the the first line before commenting... doh !

The one drive I fixed it wasn't sticking to it (physically)... but the 
drive was
holding the heads against it hard electrically (felt stuck with drive 
on).  I
think it holds hard against this looking for track 0... then fine ajusts 
for track 0
center.... if that bumper changes geometry with age, or gets moved over 
then it can't get a read on track 0.... hence why adjusting it by a 
thousandth if
an inch in my case got the drive working nicely....

-- Curt

-- Curt

> -Seth

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