Model Forum / General / Railroads / April 2007

... sorry, make that PROTO 1000

All of the major manufacturers make 9-pin-to-8-pin connecting
cables. And TCS makes a 7-pin-to-8-pin cable for their "mini"
decoders for small locos that don't have a reverse direction
light.

The extra wires on the 9-pin decoders are for Function outputs.
On DigiTrax decoders the green wire is F1, the violet is F2.

Len

   Most all Digitrax HO-scale decoders have the 9-pin connection, and have
for as long as I can recall (going back to the DH120's at the very
least...and that's around 1998, IIRC).  Lenz and NCE I believe also use them
on some decoders.  On the Digitrax DH12x series, those two extra wires serve
no purpose and I snip 'em.  On the DH14x and DH16x types, it's the function
leads for F1 and F2.
   The nice thing about 'em is that they are keyed, so it's not possible to
plug them in backwards (unlike the NMRA 8-pin).  Also, they appear to be a
lot more robust in use.  For example, I've never broken a wire off a 9-pin
decoder harness, but I have broken several 8-pin connectors (either the wire
or the pin has broken or fallen off).
   Personally, I prefer the 9-pin over the 8-pin for the above reasons.  As
for the manufacturers, I think it's also because the 9-pin connector doesn't
need the room and circuit board space that the 8-pin requires.

Paul A. Cutler III
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