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Re: Apple IIGS Memory Expansion Card question.
Bill Garber wrote:
"Michael J. Mahon" <mjmahon@aol.com> wrote in message
EZadnWs3DfPh7s3fRVn-ig@comcast.com">news:EZadnWs3DfPh7s3fRVn-ig@comcast.com...
: Bill Garber wrote:
:
: > I believe Jameco and Digikey both sell the 41256 ram ICs.
: > Also, I may have a few 1MB ram expansion cards with them
: > if you don't mind getting a few that are bad and weeding
: > them out. In fact, I think I have a set of 24 loose ones
: > sitting in a drawer plugged into styro that you are welcome
: > to for $10 plus postage. Then again, you could just plunk
: > down $49 and get one of my 4MB cards, the RAM-4-GS. :o)
:
: Danger!
:
: Don't use styrofoam for storing ICs. Though it provides
: mechanical support for the leads, it is an insulator that
: promotes ISD damage rather than protecting.
Really? I've had these chips in and out of this same styro for
a couple years, and they've always worked. Maybe this is static
resistant styrofoam. One piece was packaging for a monitor, and
the other was packing from another type of electronic equipment.
Some styrofoam is pink (or occasionally green), indicating that it
contains an additive to cause it to be slightly conductive, to reduce
its natural tendency to build up _huge_ static charges. But, though
this is better than untreated styrofoam, polystyrene in any form
remains unsuitable for holding static-sensitive components.
Styrofoam, or expanded polystyrene foam, is a _very_ good generator
of static charges by rubbing, breaking, or separating. Making
anti-static styrofoam is like making non-sticky taffy. ;-)
: Use the black carbon-impregnated foam for IS storage--or
: keep them loose.
I checked into getting some of that, and man, is it expensive.
It also has a tendency to become brittle over time. Have you
noticed this about it???
It's true that it is not inexpensive--no doubt because it really
has only one use, so it is not a mass market item. But a little
goes a long way. I also find that it tends to become brittle with
age (like me ;-), but it is not a problem for decades (again, like
me ;-) unless, perhaps, accelerated by air pollution (again,..you
get the idea! ;-).
Most ICs are stored in anti-static plastic tubes or "loose" in lab
environments, with the exceptions being CMOS ICs (including RAMs),
which are usually kept in conductive foam when not in tubes.
: In over 20 years, out of thousands of new and used "candidates",
: I've only seen two bad DRAM chips. They are so reliable (unless
: mistreated) that they are hardly worth testing. The same is
: true of almost all 74XXxx ICs. BTW, one was a hard failure
: (easy) and the other was a heat-related intermittent (harder).
I have come across many mistreated ICs in my time, and yes, people
are very hard on them. Missing the pin socket is the most common
of the problems I have run into with IF cards and motherboards
that I've received. Unbelievable how many people don't take the
time to make sure the pins are going into the socket correctly.
I can't begin to count the number of ICs that I have found on the
floor, mangled beyond recognition. Invariably, when I carefully
straighten the pins with needlenose pliers, they have all been
perfect (unless the degree of mangling or my ineptitude resulted
in a lead breaking off).
The sure way to insert ICs is with an inserter tool that holds the
leads at precisely the correct spacing. Most people don't have one
or don't use it. In that case, the "missing step" that causes the
most trouble is not "forming" the IC's leads by holding it sideways
and gently pressing each side's leads against a flat surface until
they bend a bit toward the center of the IC. This causes the tips
of the leads to have the same separation as the socket, and makes
insertion accurate and easy.
Some people have developed the skill of partially inserting one
side's leads first, then "tipping" the IC so as to bend the inserted
leads slightly to bring the other side's leads into alignment with
the socket. This maneuver is a little tricky, and can get people
into trouble if they don't do it a lot. It works best when using
the thumb and forefinger of both hands to hold the IC.
Pre-forming the leads works best if you don't use an inserter.
Of course, a final visual inspection of both sides of the socket
is required regardless of how the IC is inserted. A pin that
missed the socket or a pin that is bent under the IC will be
easily seen.
-michael
New Applesoft BASIC interface for NadaNet networking!
Home page: http://members.aol.com/MJMahon/