Reverse engineering vintage PCBs

[mark at markesystems.com]

> From: Alan Hightower <alan at alanlee.org>
>
> I appreciate all the input from folks. With 3600 though holes and at
> least 4 layers, I'm afraid I will make mistakes using any manual method
> like ohm tracing without a check or balance. With so many permutations

If it is indeed a four-layer board, there's a pretty good chance that the 
inner two layers are power and ground; if so, your project just got a lot 
easier.  You can just hold it up to a strong light source - if it's 
completely opaque, then the inner layers probably are power/ground planes. 
If not, then at least you can see the traces (although without knowing which 
layers they're on...).
~~
Mark Moulding