Testing Power Supplies! Re: Norsk Data Nord-10/S restoration effort on the way!

[Tore S Bekkedal]

On Mon, 2004-11-15 at 13:11 -0500, Paul Koning wrote:
> >>>>> "Joe" == Joe R <rigdonj at cfl.rr.com> writes:
> 
>  Joe> Testing power supplies before powering up a system is just plain
>  Joe> paranoid! (And I'm trying to be polite here!) There are a
>  Joe> thousand parts in modern computers that can cause just as much
>  Joe> damage!!!!!!!! 
> 
> I disagree -- at least in the case of linear regulator supplies, which
> is what you'll normally find in a classic computer.
I am for testing them in some cases, like the PDP-7. I was without much
experience at the time, and with a machine of which 6 are known to
exist, I would MUCH rather err on the side of caution and spend a few
hours testing/reforming caps than watch the fireworks of computer
history.
> If the supply has a "crowbar overvoltage protection" circuit in it,
> that's a different matter. 
This PSU is rugged and has "Voltage OK" lights on all the voltage lines.
It is according to a man who is knowing, incredibly sturdy and used with
defense systems all over the country.
>  But testing a linear supply is trivial.
> So why not do it?
TRIVIAL? All the leads running into the PSU are *BOLTED* on two large
bars labelled -5V and +5V. I had no tools at the time. The PSU itself is
inside the rack and there it will stay until I get it out, which I'm not
going to, because the thing is held in place by numerous screws and is
shit-heavy. If I got the screws loose, it would probably crash down on
the CPU.
> 
> If you let the magic smoke out of the  computer, it's too late...
In this case, no magic smoke as expected.

But access to a complete array of spares if nessecary. Oh, and the CPU
is built in TTL logic, so no hard-to-get spares. (Not that magic smoke
is *desirable*!)

I stand by my desicion to test the PDP-7, and not to test the Nord-10/S.
-- 
Tore S Bekkedal <toresbe at ifi.uio.no>