Re: RAM-4-GS testimonials

["Michael J. Mahon" <mjmahon@aol.com>]

jsnospam@cimmeri.com wrote:
> I'm afraid I wouldn't buy a card that didn't have gold fingers either.

At the risk of approaching a hornet's nest, I'd like to offer what
I was told by an experienced mainframe designer at HP.

Gold plating--on *both* connector and card edge--will produce a
corrosion-proof connection only as long as wear does not expose
the underlying (oxidizable) metal on *either* part.

HP was prone to specify a gold plating that was several times thicker
(and more expensive) than most standard connectors and card edges.
He figured that the connection was reliable for up to a couple of
dozen insertions and removals, after which either the connector or
the card edge fingers had received sufficient wear that oxidizable
metal was exposed.

Since the connectors used in most electronics, including the Apple II,
are not "heavily" gold-plated, and since most Apple II card edge 
connectors are not heavily gold-plated either, their expected non-
oxidizable lifetime is closer to a half-dozen insertions and removals.

(This is why, he said, that for any application where numerous
insertions and removals are expected, gold plating is more *cosmetic*
than functional.)

Since almost every Apple II memory expansion connector has had
an expansion card inserted and removed a half-dozen times or more,
it is not likely that any initial gold plating remains effective
in creating a non-oxidizable connection.

Note that inserting a new card into an old connector doesn't
restore the connection's integrity, even if the new card is
gold plated.

Also, *any* abrasion of the gold plating, even that produced
by a soft eraser, will make it look prettier by abrading and
polishing the very thin layer of gold, only *adding* to the
wear and reducing its corrosion-resisting capability.

Cleaning contacts is sometimes necessary, when they have been
contaminated by oxidation or debris, but cleaning should be done
very carefully so as not to remove any gold, if they are gold-
plated.

Tinned contacts can be cleaned with a mild abrasive, like a
soft eraser, but this, too, must be done carefully, since debris
from the eraser that gets into a connector can be a worse problem
than oxidation.

In most cases, the inevitable surface oxidation on a tinned edge
connector will be "cut through" just by the act of inserting the
card into the connector, by the wiping action of the connector's
contacts.

This is why most card connection problems are solved, at least
temporarily, by removing and re-inserting the card, and why
"skooching" socketed chips up and re-seating them often restores
good connections.  (BTW, note that tinned chip leads and chip
sockets are almost universal.  *And* that sockets should be
avoided wherever practical to improve reliability!)

-michael

New, faster SUDOKU v2.0 solver for Apple II's!
Home page:  http://members.aol.com/MJMahon/

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