Testing Power Supplies! Re: Norsk Data Nord-10/S restoration

From: Tony Duell <ard_at_p850ug1.demon.co.uk>
Date: Mon Nov 15 18:11:19 2004

> "Voltage ok" may mean there's a crowbar, or it may only mean there is
> a voltage monitor. Those are very different things. Voltage monitors

I would suspect that latter, and not a particularly good monitor at that.
I've met PSUs where all the 'idiot lights' were on, but there were still
problems (excessive ripple on one of the outputs, for example).

> wouldn't protect you against a regulator short.
>
> Tore> But access to a complete array of spares if nessecary. Oh, and
> Tore> the CPU is built in TTL logic, so no hard-to-get spares.
>
> TTL is getting hard to find, especially the more obscure types such as
> 74S series. (And if the book says they want 74S, it's quite possible
> no other variant will work...)

74S is trivial to find comparied with 74H (and yes I have found those in
classic computers) or 74L (not 74LS, of course) .Even some plain 74xxx
numbers are non-trivial to get now -- 74181 ALU, 7489 RAM, the fusible
link PROMs, 7456 and 7456 (mains - 1Hz dividers), etc, etc, etc. A look
through an old TTL databook will show a few dozen devices you'll no
longer see in the catalogues.

-tony
Received on Mon Nov 15 2004 - 18:11:19 GMT