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Subject: Re: [Homebrew_PCBs] Reproducing Unavailable Circuit Boards

From: ron amundson <mnphysicist@...>
Date: 2005-09-23

> Hi all,
>
> Didn't see any discussion on this topic in past
> posts, so I thought
> I'd throw this out to the group...
>
> I am trying to reproduce a circuit board for a very
> old arcade game
> from 1975. Its an old style pitch and bat game, so
> the electronics
> are fairly simple, but the board is huge (approx
> 13x19") with about
> 100 TTL Logic chips and various resistors/capactors.
> Double
> sided... This board is no longer available and I
> have not been able
> to locate a board for quite some time... I was able
> to borrow a
> board from a fellow collector, but it is only
> on-loan. I also have
> the schematics...
>
> My question to the group: Does this sound like a
> resonable process
> to reproduce this board:
>
> 1) Remove all components from board
> 2) Scan in both sides (double sided board)
> 3) Touch up artwork and output to transfer paper
> 4) Transfer images to copper clad board
> 5) Etch, drill, populate...
>
> Is this the process most of you would follow to
> reproduce a board?
> Or am I missing an easier process? I actually
> thought about re-
> designing the board a little smaller, but I cannot
> afford the cost of
> an auto-routing software package to do a board of
> that size.
>
> Any thoughts or suggestions?
> Thanks!
>
> Tony
>

One other concern. Can you still get the parts? A lot
of logic at that time is no longer made. Most newer
parts have much faster risetimes, and as a result,
what worked then, may no longer work with todays
parts.

Occasionally we would be asked to reverse engineer,
and bring an old product line back to life. In a lot
of cases, this usually meant setting up a micro or
fpga to recreate the functions, rather than trying to
make a duplicate of an old design. Otoh, these were
not one off units, normally if someone wanted an old
product brought back into production, they wanted 10's
if not 100's of thousands of units, thus making the
process worthwhile.

In other cases, we might have the pcb digitally
xrayed, and then separate out the board layers. That
way, the golden unit would not be susceptible to
damage, and we could test and verify the new design
against what might be the one and only working old one
still in existance.

Ron




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