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

From: Tothwolf <>
Date: Sun Jul 21 20:22:01 2002

On Sun, 21 Jul 2002, Tony Duell wrote:

> I think that sounds far to low to move the heads -- I would expect a few
> volts at least. So you might well have a servo problem. As a first
> attempt (not having schematics), check the power transistors on the
> servo board. I think 6 of them are to drive the spindle motor, the other
> 4 (?) are the servo power amplifer. The V150 I worked on used discrete
> transistors (not an amplifier chip), so I would guess the V170 does too.

I checked the voltage again, with the servo plug disconnected, and got
just under 12VDC across the terminals. With the servo plug connected, it
reads right at 0.4VDC.

Maybe the head lock is indeed stuck?

Received on Sun Jul 21 2002 - 20:22:01 BST

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