18 Jul
2009
18 Jul
'09
5:45 a.m.
> You are right about the RD53s though. The one that came with the
machine
> seemed a bit dubious to me but seemed at
least to respond in some
way (I
> could start a boot but it would never
complete). Then one day it
just went
> offline as if it is not attached at all, I
wonder if this is not a
> mechanical problem but an electronic one in this case? Is there
anything
that can
be done to revive them?
Most likely you've run into the sticky pads problem. Hopefully >basically you open the drive up and remove
the sticky rubber pads.
I
really
servo
don't remember the details as I went SCSI
nearly 10 years ago.
Zane
If it spins up then back down and repeats thats a stuck head
positioner.
When the drive is powered down there is a magnetic retract and at the
end of travel there are bumpers that betwen heat and time get sticky.
The windup then down is the failure of the heads to move and find and it fails.
There are two fixes, temprorary is to freeze the drive and sometimes
they unstick. Me I open the drive, unstick the heads and reach in to
the mech and pull out the goo they stick too. Never had a failure
yet
and all 6 of my RD53s are salvaged this way and
most were opened over
10 years ago (two approaching 15!) and they are well past their MTBF
now. I haven't opened any in years since I haven't found more and
generally RD53s are more useful to me as spares, swap or for the Qbus
pdp 11s I have. Other than that goo problem they were otherwise
reliable drives.
I have opened up the drive by removing the top plate and I have not
found
quite what I expected. The heads are positioned under the platters, I
expected that when retracted they would be to one side of the platters
instead. The platters rotate freely but the heads so indeed seem to be
stuck
in that I cannot move the arm (at least not without applying some
force), I
am assuming that they are stuck because of the goo you mention. What I
am
not sure about is just how to unstick the heads, there does not seem to
be
much to get hold of and I am worried that applying too much force may
break
something. Once I have the heads unstuck the goo is going to be in-
between
the platters, is that right? I cannot see how to get at the goo to
clean it
up in that case.
Any advice on what to do? Do I need to remove more parts, or can it be
done
just by removing the top plate?
Thanks
Rob
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robert.jarratt＠ntlworld.com