5 Jan
2021
5 Jan
'21
1:53 p.m.
-----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 l?r 2 jan. 2021 kl 19:34 skrev David Gesswein via cctech <
cctech at classiccmp.org>:
I just used a sliver of paper as a shim. It is probably not ideal, but it worked for me.
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. 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
> > >
> > >
> >
> >
> > ------------------------------
>