18 Jul
2009
18 Jul
'09
5:57 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
Allison
>answers this, as I believe she has experience reviving RD53's. >basically you open the drive up and remove
the sticky rubber pads.
I
> really
> >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 > 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
servo
> and it fails.
>
> There are two fixes, temprorary is to freeze the drive and > 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 > 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 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
I tried a bit more this morning and I have managed to loosen the arm
carrying the heads to some extent. I can now move the heads back and
forth a
bit, but only about 5mm across the platters. What I am not sure about
is how
free the movement should be when there is no power, should I expect to
be
able to move the heads across the whole surface, or just the 5mm or so
I am
able to do now?
Regards
Rob