Depending upon the service environment, the steel wire may corrode since it
is in contact with the more noble gold plating on the D9 connector.  If you
could do something similar with gold-plated brass, it might be more
reliable wrt corrosion.

I think a "dongle" or a very short adapter cable would be more elegant.


Karen Tellefsen - Electrical Testing
[log in to unmask]
908-791-3069


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Carl VanWormer
Sent: Wednesday, August 19, 2009 11:38 AM
To: [log in to unmask]
Subject: [TN] Guitar string shorting jumper

We have need to "permanently" connect two adjacent pins of a female DB-9
connector that has a molded housing, so we can't get at the back side of
the connector for a properly soldered connection.  The first suggestion
was an adapter (male and female connectors, PC board, and insulating
housing or heat-shrink cover).  For the planned quantity of 50 units,
this design effort seemed like a bit of overkill, even ignoring the size
of the ugly protrusion of this adapter out the back of the product.

An alternative is being considered that needs some "fatherly guidance"
from the collective TechNet intelligence:
A short length of .008" steel wire guitar string with a U-bend to span
the two female terminals could be inserted into the proper terminals of
the female DB-9 connector.  If the two legs were bent back on
themselves, forming barbs, the shorting jumper could be inserted into
the DB-9, with the barbs performing a lock-in function to hold the
shorting jumper in place.  A quick test of a bent-up sample indicates
that this approach seems to work well, with only minimal distortion of
the female sockets.  The final product is expected to have only a few
insertion/removal cycles in its lifetime.

The questions to this group are:
1.  How crazy am I to suggest this solution?
2.  Should I consider Gold plating (or something else) to increase
reliability?

Thanks,
Carl

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