Reverse engineering vintage PCBs

[Alan Hightower]

Does anyone have any past experience reverse engineering an existing
de-populated PCB into a scan, netlist, or similar? Any lessons learned
positive or negative? 

I have a AT&T 3B2 310/400 main board that is beyond salvaging into a
working system. A previous owner has also removed the socketed parts
including the Western Electric chip set. I'm unable to find working
schematics of most of the 3B2 cards and main boards. So I'm considering
bulk de-populating the remainder of the board in an oven and trying to
derive a schematic from it. It's a fairly large board but appears to be
100% through hole. I roughly estimate it contains ~3500 through holes.
And guessing it is 6-10 layers. Thus running it through a single vector
x-ray machine would not be very useful. 

I've brain-stormed several ways it can be done from de-laminating the
board, building a 2D bed of nails armature, mirroring the board holes on
a new mated PCB with 3 dozen FPGAs, etc, etc. But I'm seeking advice
from those who've done it already. 

Thanks, 

-Alan