Wiardgroup

Hi all

--- In wiardgroup@yahoogroups.com, "tom_tav" <tom_tav@...> wrote:
>
> Unfortunately if you want to service an instrument somedays you will
sooner or later having 
> problems to get something else then smd parts....
> 

this is true, but the decision for a technological cottage industry is
anything but clear right now...

a few questions about surface-mount technology are stacking up in my
mailbox so here's my take:

background:
SMD,SMT,SOIC are all jargon for pretty-much the same thing:
itty bitty parts that you can move with a sneeze and don't have any
nice bendy wires stickin' out of 'em.
the wiki on this subject is pretty good  
http://en.wikipedia.org/wiki/Surface-mount_technology
These things are made for the convenience of robots and not for human
fingers.

More germane to this forum is the issue of reparability. It's true
that the older DIP devices will suffer from a scarcity of replacement
parts. But this evolutionary precipice in hardware is a bit unique in
that the components are virtually identical electrically but they are
physically much smaller.  In this way this is not like the migration
from tubes to discrete transistors. The scale of physical
miniaturization was comparable but  power environments moved from high
voltage unipolar to lower voltage bipolar and the active components
had VERY different electrical properties. 
SMD is optimized for mass production by automated processes. Component
level repairs are not part of the plan. The intention is to reduce the
cost of the circuitboard to the point that replacement is cheaper than
repair. This works pretty well for cell phones produced in production
runs of 50,000 units but those scales do not favor small run esoteric
devices. Small run SMD boards don't run cheap enough to garner the
advantage of being disposable and replaceable.
Component-level repairs to SMD are possible but significantly more
difficult and time consuming .  i'd contend that the profile of
increased risk and difficulty of SMD repair is different but
equivalent to the tradeoffs inherent in through-hole (DIP) (ie. easier
repairs but scarcer parts). In a pinch I think it is easier to adapt a
smaller SMD chip to a through-hole application than the reverse.

The wiard designs (what's on the schematic) are very durable but  the
technology available to realize these 'songs in solder' is in a real
state of flux right now.*** The consequences of the choices that face
Prof. Richter (and his colleagues) at this juncture are VERY serious,
and there is no path that offers a CLEAR advantage right now.

aleatoric music is way more fun than aleatoric livelihoods.

-doc

PS
apologies to the group for all the button-thrashing empty posts this
morning

***
even  -i- don't KNOW if that pun was intended or not