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

From: Tothwolf <>
Date: Wed Jul 31 03:40:01 2002

On Sat, 27 Jul 2002, Tony Duell wrote:

> Interesting. Maybe the lock is not releasing. Or maybe the heads are
> being rammed into one end stop due to the lack of servo signal from the
> heads. But how come the drive voltage is so low?

I don't hear the heads move much at all. It sounds like they are trying to
load, but just don't move. I don't hear any of the typical sounds I hear
from other drives when their heads load.

> Have you traced out the connections to the connector you think is for a
> positioned lock? On the V150, one pin is grounded. The other goes via a
> power transistor to +123V (MJE210, PNP) to pull the solenoid in, and via
> a resistor and annother MJE210 transsitor to +12V to hold it. Does that
> sound similar?
> If this is the head lock solenoid, do you get any voltage across it when
> the drive is attempting to spin up?

I think I did get voltage on that connector when it seemed to pull in.
I'll have to double check though.

> A silly test, but one worth doing. The V150 uses a diode/capacitor
> circuit driven (indirectly) from the master clock to generate a -ve
> supply voltage to the op-amps. If it malfunctions, all sorts of things
> will malfunction (both because of the missing supply and because a
> protection circuit will clamp signals, etc). Can you just check the
> voltage at pin 4 of some of the 4558s?

I'll certainly check it.

> Unless you have a clean box, I would do a few more checks outside the
> HDA first

Well, ok :P

Received on Wed Jul 31 2002 - 03:40:01 BST

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