NOVA4 6070 disk

From: Tom Jennings <tomj_at_wps.com>
Date: Thu Feb 3 15:42:17 2005

On Thu, 3 Feb 2005, Dwight K. Elvey wrote:

>> (While the bottom platter was out I wiped everything down with a
>> kimwipe and 99.5% isopropyl.)

> First, although kimwipes leave little lint, they do
> leave some.
> As a person that has done mirror grinding, I can tell
> you that one of the most sensitive ways to see if there
> is anything stuck to the surface is with your finger.
> You can feel things that you can't even see. It
> is quite likely that there was still something on the
> heads surface. If you use your finger to check the surface,
> you can follow with one of those foam swabs and alcohol.
> You should first clean as much oil from your finger before
> using it to test the surface with some alcohol as well.
> Also watch out for the back edge of the heads. These
> are often very sharp and if you rotate the disk backwards
> against the head, it will dig into the disk surface.
> Anyway, feel the surface of the heads with your finger
> before you consider that you have removed all the gunk
> that could do damage. It should be silky smooth.

Thanks for the tips. I will yank the upper head (luckily the
easiest to get at) for a close examination, like maybe a fiber
dangling from the metal frame or out the hole.

The heads are retracted unless the platter is at speed; even with
a power-fail it retracts, there's a huge capacitor that dumps into
the linear motor via normally-closed relay contacts. They never
touch when not rotating (CCW). They never clacked together (top
and bottom heads) (they want to do that during install/remove), or
whatever.

The terrifying thing is of course that testing isn't possible.
I've got one good cart left. If I don't positively locate the/a
problem I won't install it.
Received on Thu Feb 03 2005 - 15:42:17 GMT