Multibus ST-506/QIC-02 (was: Re: SGI IRIS 1400 ...)

From: Tothwolf <tothwolf_at_concentric.net>
Date: Fri Aug 2 07:18:00 2002

On Thu, 1 Aug 2002, Tony Duell wrote:

> > third 4558 seems to have pin 4 grounded (according to an ohm meter),
> > which seems strange, to say the least.
>
> No, it's possible to run them off a single supply. I think some of the
> op-amps in my V150 are run just between the +12V line and ground. I
> would have to check, though.

Ah ok. I thought the 4558 required a dual supply. I should re-read the
datasheet I suppose...

Some of the other 4558 chips on other hybrid modules appear to be
operating at +12V too. There are a large number of 4558 chips used on all
the different hybrid hybrid boards. I'd guess there is at least 10, maybe
more. There are some 8 pin dip ones mounted directly to the servo board
too.

> It may now be worth pulling the cover and taking a look. And of course
> trying to spin it up with the cover removed, just to see what the heads
> do

Is it safe to try to spin the drive up without the HDA cover installed? I
always assumed it wasn't safe, since the cover would help direct the flow
of air around the heads and keep them from resting on the platter surface.

-Toth
Received on Fri Aug 02 2002 - 07:18:00 BST