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

From: Tothwolf <>
Date: Sat Jul 20 20:59:01 2002

On Sat, 20 Jul 2002, Tony Duell wrote:

> Argh!. Unfortunately the drive I worked on was the type without the
> hybrids. While I think the circuitry is _very_ similar, there will be
> differences in the component designations. So I can't tell you exactly
> which testpoint to look at :-(

Ouch. Well, I imagine one way or another I'll get something working...

> Do you have an analogue voltmeter? If so, connect it between the pins of
> the larger 2 pin connector at the front edge of the servo board (black
> and white wires?). That's the drive to the positioner coil. If you get a
> voltage there it's attempting to move the heads.

Of course! Who doesn't? :)

I got 0.4VDC across the connector. It jumps to 0.4 after it spins up for
about 8 seconds. The drive spins down after about 20 seconds total. I hear
a "click" at the 8 second point right when the heads are trying to load,
but it doesn't sound like they load. At the 20 second point, I hear a loud
"clunk" and the drive spins down.

> It's quieter than one of the old stepper-motor-positioner drives, but
> you should be able to hear something.

How fast do these drives spin? It sounds like it is spinning quite fast
for such an old drive...

> Argh!. We have no idea what condition the heads or platters are in,
> then. Do you know if it's ever worked since being dismantled? Is it
> worth taking the cover off again (in as clean an environment as you can)
> to have a look?

I have no idea who took it apart, but it would have been done while the
system was still in England. I don't know if it worked or not after that,
but considering there was a tag on the DSD 5215 that stated something was
wrong with it, I'd guess the drive wasn't working. Best I can tell
(without another drive to test with) the 5215 is actually working just
fine. It appears the original system owner must have owned more than one
1000 series IRIS, and just swapped the hard drive and controller when it
quit working.

I'm somewhat tempted to take the cover off the HDA, but the cleanest place
I have to take a peek is the shower after I let the room steam and then
dissipate. Granted, that may be cleaner then the last place the HDA was
taken apart.

I really should build a clean-box...

> There's an electronic brake on the servo board (that's what the relay K1
> is for), but with the motor disconnected from the servo board (the
> multi-pin connector at the back edge), the motor should feel fairly
> free. It will tend to settle in one of a few positions though, as the
> magnetised rotor goes past the cores of the coils.

Would the small connector with the two white wires that is near the servo
connector be the spindle brake?

I took some some fuzzy photos of the HDA and boards with the digital
camera. If you think they might help identify anything, you can find them

Received on Sat Jul 20 2002 - 20:59:01 BST

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