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

From: Tothwolf <>
Date: Sat Jul 20 17:09:00 2002

On Sat, 20 Jul 2002, Tony Duell wrote:

> Firstly, there are 2 circuit boards on the bottom of the HDA. The one
> you can see contains the R/W chain, index circuit and the
> microcontroller (8051-thing). That microcontroller enables the spindle
> motor, controls the head movement for seeks, and so on.
> The board under it (right next to the HDA) contains the servo circuitry.
> There are at least 2 versions, one covered with little hybrid circuits,
> the other using mode conventional (but SMD) components. I think that's
> the later version, but I wouldn't bet on it.

The boards on the V170 sound identical. The board with the servo circuitry
does use those hybrid circuit things (they kinda remind me of SIP memory
modules and time delays).

> Can you find the servo preamp (if there is a 2-wire servo jumper between
> the PCBs, then it goes to the input of this stage). If so, is there any
> signal on the output when the drive is trying to spin up? What about
> positioner drive (there's a larger 2-wire connector for this on the
> servo board, going to a cable that goes into the HDA). Anything there?
> Can you feel/hear the heads attempt to move when the drive is spinning
> up?

The 2-wire jumper is there... Unfortunately I don't have a functional
'scope. I have 3 60MHz scopes all sitting without probes (or docs, but I
can manage).

I didn't hear the head load noise I'm used to hearing from FH ESDI drives.
Would it sound very similar?

> You might have an electronic fault that can be cured. If you think the
> drive is in any way similar to the V150, I can provide a little more
> info.

It sounds nearly identical, so maybe it isn't a lost cause after all :)

I'm not sure if I mentioned this in an earlier email or not, but the foil
seals that cover the screws on the top of the drive have been tampered
with. Its possible someone may have opened up the HDA in a non-clean
environment, or the drive might have been serviced at some point.

The spindle motor is exposed on this drive with the boards removed, and I
noticed it felt "sticky". Is that normal for these drives? Do they have
some sort of brake?

Received on Sat Jul 20 2002 - 17:09:00 BST

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