[Oberon] Updated RiskFive FOM schematics

[Paul Reed]

Hi Peter,

> These days, my first concerns with any new electronic machine is
> reliability and repairability.  Too many gadgets are built with poor
> quality, barely in spec. components, surface mounted.  After a few
> years a board fails.  There is no straigthforward way to identify the
> failed component.  Replacing a surface mount component is tedious and
> error prone.  Replacing a many-pin device just to find whether it is
> faulty is too time consuming.
>
> Conclusion: a board with components mounted in sockets and through
> hole soldered would have much more appeal than fragile components
> surface mounted.  Perhaps simply not feasible in our world and I
> should forget modern electronics.  No offense intended.  Just an frank
> comment.

I both agree and disagree with you. :)

Obviously the intention with surface-mounted devices (SMD) is that boards
can be produced so cheaply that you just throw them away - neither you nor
I like that wastefulness, but it's certainly cheaper than the time to
diagnose it (time being money).  Also, sockets have their own
unreliability.

And SMD means you can lay out a lot more on a board - if the board is so
big it flexes a lot, that's another unreliability.  But when manufacturing
in the hundreds of thousands, the temptation is to use "only just" enough
solder, and too much is often problematic in automatic processes - so this
may be giving the principle of SMD a bad rap.

On the other hand, I've watched with interest and admiration as what is
now called the "maker" community grapples with the unavailability of
through-hole parts.  They even have great success hand-soldering ball-grid
array chips these days.  Maybe the way forward is to use SMD, but design
for hand-re-workability wherever possible.

Just my two .5mm-spaced pins :)

Paul