Re: CBM-II solderless memory expansion

Den Fri, 20 Apr 2018 08:12:14 -0400 skrev David Wood
<jbevren@gmail.com>:
> For what it's worth, Fairchild has a 74LCX line as well if everyone's
> looking for keywords to search for.  I've used a 74lcx245 to build a
> parallel-port JTAG adapter some time ago.
> 
> http://jbevren.net/pixter/debugstation.jpg, seen on the prototyping
> board in the upper right.
> 
> They're incredibly handy and I recommend tinkers always have some on
> hand in case they run into some 3.3v logic they need.
> 
> Also, don't fear SMT.  I did for ages but found that it's really not
> too difficult once the process of soldering it is practiced a few
> times: http://jbevren.net/pic/8kinside/1--smt-parts.jpg was
> drag-soldered, and is one of the first SMT solder jobs I'd done.

In my (antiquated) experience, soldering SMD is mostly a question of
having really good microscope, preferable a stereo microscope. Of
course you also need some reasonable soldering tools but that is'nt
that critical.

I used to work at a place that had good streo microscopes. At that
time, about 20 years ago, those cost about 20000 SEK, about €2000, in
that times money value. Today I'm sure there are electronic ways to
make this far cheaper though.

I think that you would want both a small enough soldering iron and also
some kind of hot air thing. Hot air is good for desoldering and
soldering small 2/3 pin components and solder most legs of an IC while
the small soldering iron is good for soldering the first few pins of an
IC before using hot air to solder the rest.

Also there is a really big difference between different SMD stuff. The
one on your picture has halv the pin spacing of standard DIL and isn't
that hard to solder. You might be able to solder that without any
microscope and with a larger soldering iron (like even the biggest flat
tip on an old Weller Magnastat or similar). But for some other stuff
like some CPLDs the pin spacing can be far tighter and thus much harder
to solder without the right tools.

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