29 Dec
2006
29 Dec
'06
2:05 p.m.
Wow - that is _really_ cool. I wish I had access to an
X-ray machine - it certainally would make reverse
engineering/repairing boards a lot easier. Although I
wonder what a complicated multilayer board would look
like. Probably unintelligible, but then again, the
hardware we all work with doesn't have complicated
multilayer boards.
Well, if the board is just double sided (i.e. all tracks visible, except
where they pass under components), you can generally trace tracks by eye
and confirm with an ohmmeter. And if there are internal tracks, I think
tracing those from an X-ray image wouldn't be exactly trivial.
For boards where the layout of the tracks is not critical (that is, there
are no inductive or capactive couplings between tracks), I've never had
any problems tracing out the connections with an ohhmeter. You have to
desolder components that will test as dead shorts (inductors,
transformers, low-value resistors) of course, but such components
generally have few conenctions are are not hard to remove.
If the layout is critical, of course, you have problems. Mind you, I'd
love to see anyone fiogure out the HP9100 ROM board (14 layers, or is it
16) from an X-ray image of the board. That is probably the worst example
you'll find in a classic computer.
-tony