ICL PERQ 2 T2 Micropolis 1303 spinning down.

[David Gesswein]

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.

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
> >
> >
> 
> 
> ------------------------------