ICL PERQ 2 T2 Micropolis 1303 spinning down.

[Rob Jarratt]

> -----Original Message-----
> From: cctech <cctech-bounces at classiccmp.org> On Behalf Of Mattis Lind via
> cctech
> Sent: 05 January 2021 17:52
> To: David Gesswein <djg at pdp8online.com>; General Discussion: On-Topic
> Posts <cctech at classiccmp.org>
> Subject: Re: ICL PERQ 2 T2 Micropolis 1303 spinning down.
> 
> 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.
> >
> > http://www.pdp8online.com/rd53/rd53.shtml
> >
> > Shim picture.
> > http://www.pdp8online.com/rd53/pics/lock.shtml?small
> 
> 
> 
> Thanks. Good advice and good prictures! Need to find some material that
> makes a good shim then. 

I just used a sliver of paper as a shim. It is probably not ideal, but it worked for me.


> It will be very interesting if this solves the problem.
> I wonder if the other symptom I saw where the drive kept spinning while the
> head was moving back and forth also is related to the first? It didn't sound
> like full seeks but rather quite short. The drive kept doing this for maybe one
> minute and then spun down.
> 
> 
> /Mattis
> 
> 
> >
> >
> >
> > 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
> > > >
> > > >
> > >
> > >
> > > ------------------------------
> >