ICL PERQ 2 T2 Micropolis 1303 spinning down.

Chris Zach cz at alembic.crystel.com
Sat Jan 2 08:25:24 CST 2021

> 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?

Yep, and I'm sure a lot of drives from this era have the same issue. Or 
the grease in the bearings has separated out. Stuff like that. In the 
inside of the HDA the oil is probably still there, just needs to re-mix 
with the clay and binders that make grease grease. On the outside 
bearings the oil has probably been evaporated and needs to be replaced 
(new oil will mix with grease and work).

On a high performance Porsche, the exact type of grease for a wheel 
bearing is critical and mixing of grease and oil is bad because it's 
400+hp behind all that. A hard drive is probably a lot more forgiving 
but too much oil could wash out the clay which means the oil won't stick 
in the bearing.

The big problem is torque: Original coil type head assemblies had a LOT 
of torque. Modern motors and the like have a lot less starting torque 
because it's not normally needed. But on an old disk you don't have 
enough torque to overcome the sticky pad or to mix the grease/oil and 
it's stuck.

One thing I have been concerned about is if the heads have stuck to the 
platter. If that happens, then turning the spindle will probably rip the 
heads off. Not sure how to address this.


> /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

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