4 Apr
2011
4 Apr
'11
4:58 a.m.
On Mon, 4 Apr 2011, Terry Stewart wrote:
I recently added some sockets and replacement 4164
chips on Lisa RAM boards
as Ian and others on the Lisa List will know.
(see
http://www.classic-computers.org.nz/blog/2011-04-02-fixing-lisa-memory-card…
is you want the details.)
These multi-layer boards are tricky, and I did manage to nuke a couple of
lines. I usually use solder wick to clean out the holes, but these were the
most difficult I've come across (then again, I had very limited experience on
multi-layer boards).
My Amiga was a four-layer board as well, so I've been down that road. You
can understand my trepidation at the thought of replacing a 60-something
pin card-edge connector!
A properly designed multi-layer board should be using thermal reliefs
around the Gnd and +V pins, but I'm not sure how much that is done in
consumer equipment. Its a cross-shaped structure intended to provide
thermal resistance between the via and the body of the internal plane.
Steve
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