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

From: Tothwolf <>
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

> 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.

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

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