Warming up an IMSAI P/S

From: Sam Ismail <dastar_at_ncal.verio.com>
Date: Sat Sep 19 16:49:35 1998

On Sat, 19 Sep 1998, Tony Duell wrote:

> > When its powered down, give the fan a spin with your finger. It should
> > spin freely. If not, it should be replaced. The older bronze/oilite
> > bearings dried out and would start to stiffen up after a souple of years of
> > operation.

The fan works just fine with or without power.

> > Never can be too safe. In the case of my PDP-8/i which had not been fired
> > in a known 10+ years, once I had the supplied spun up I ran it in under
> > (auto) lamp loads for a little over 6 hours (frequently checking for ripple
> > with a 'scope) before I started reconnecting logic.
>
> No, it's me as well :-). Having once had a PSU fail and take out chips, I
> am now _very_ careful when I bring up an unknown PSU.

I actually left it warming for about 4 hours while I ran around trying to
locate boards, manuals, cables, etc. in between other things I need to get
completed for VCF.

Today I plugged in the front panel and a Cromemco ZPU. It worked! The
address LEDs 15, 14 and 13 are sequencing in a binary pattern. I don't
know what this means, but at least it shows life. I got the same results
with another ZPU. I can single-step it and see different stuff happening,
but I have no idea what its doing. I buried my friggin IMSAI manual in a
box a few weeks back.

> Darn it, on an S100 machine, I'd probably pull the socketed chips from
> each board and test the regulators off-load...

I got your message after I started playing but fortunately everything came
out fine. I don't know if I should be surprised that this stuff is
working as well as it is. Aside from its age, most of this had been
stuffed away in grimy corners of peoples' basements and garages, or worse!
A lot of these boards seem so kludgy with all the patch wires they have.

Sam Alternate e-mail: dastar_at_siconic.com
-------------------------------------------------------------------------------
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                September 26 & 27...Vintage Computer Festival 2.0
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Received on Sat Sep 19 1998 - 16:49:35 BST

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