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

[Tony Duell]

> "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