ICL PERQ 2 T2 Micropolis 1303 spinning down.

[Mattis Lind]

Den lör 2 jan. 2021 kl 19:34 skrev David Gesswein via cctech <
cctech at classiccmp.org>:

> This is my info on RD53 sticking heads. Your symtoms match what I have seen
> with this drive.
>
> If the heads are stuck to the rubber bumper the drive will spin back down
> when it finds the heads won't move. It will also spin down if it can't
> switch from the coarse speed control loop to using the head servo signal.
> There is a narrow band where the heads are parked with the proper signal.
> When the rubber has deteriorated the heads are no longer over it. Adding
> shims
> can fix that. I used a tent with RK05 filter but others have opened drives
> in reasonably clean locations sucessfully. Best to keep the pets away.
>

The "shim" method worked fine. The drive spun up and I managed to dump it.
Imade six dumps and the same five sectors were bad on every read I did. So
now I have a nice dump of the PERQ 2 system. Wonder what it is on it?

I see things like :

---------------------------------------------------------------------
! LoadDisk.Cmd
! Copyright (C) 1983, 1984 - Perq Systems Corporation.
! Abstract:
!   Load version G.6 of POS onto the hard disk.

so there is some PERQ stuff there at least.


>
> http://www.pdp8online.com/rd53/rd53.shtml
>
> Shim picture.
> http://www.pdp8online.com/rd53/pics/lock.shtml?small
>
>
> On Sat, Jan 02, 2021 at 02:05:11PM +0100, Mattis Lind wrote:
> > Den l?r 2 jan. 2021 kl 11:48 skrev Rob Jarratt <
> robert.jarratt at ntlworld.com
> > >:
> >
> > > When that has happened to MFM disks of mine it has been because for one
> > > reason or another the heads have not moved and found track 0. Why they
> > > aren't moving could be more than one reason. They could be stuck, or
> there
> > > could be some other problem that is preventing them getting the power
> > > needed to move.
> > >
> >
> > Did you solve the problem? How?
> >
> > I have heard that Micropolis 1325 is prone to have a problem with a
> rubber
> > bumper that sticks to the head mechanism. Maybe it is the same for this
> > Micropois drive? What resolutions are there to this type of problem?
> >
> > /Mattis
> >
> >
> > >
> > > Regards
> > >
> > > Rob
> > >
> > > > -----Original Message-----
> > > > From: cctalk <cctalk-bounces at classiccmp.org> On Behalf Of Mattis
> Lind
> > > via
> > > > cctalk
> > > > Sent: 02 January 2021 08:59
> > > > To: General Discussion: On-Topic and Off-Topic Posts
> > > > <cctalk at classiccmp.org>
> > > > Subject: ICL PERQ 2 T2 Micropolis 1303 spinning down.
> > > >
> > > > I have a nice ICL PERQ 2 T2 that I am going to start working with
> now.
> > > >
> > > > First thing was to try to image the hard drive. It is a Micropolis
> 1303.
> > > It spins
> > > > up but when it reaches what I think the correct speed it immediately
> > > spins
> > > > down. Usually I think there would be a click and then the heads would
> > > > recalibrate. But there is no click and no head movement.
> > > >
> > > > I really would like to make an image of the drive.  What are your
> > > thoughts?
> > > > Are the heads sticking?
> > > > Some kind of solenoid that is not releasing the heads? Not properly
> up to
> > > > speed? (but it sounds like the speed is right)
> > > >
> > > > /Mattis
> > >
> > >
> >
> >
> > ------------------------------
>