May I use outside of connector to carry signal?

[martianviking]

First, let me say that I don't want to do this.  I don't take this departure from common sense lightly.  But...

Given that pin 8 on the Neo Geo controller pinout carries +5v, it would appear that there aren't quite enough pins on the Neo Geo (DB-15) connector for 8 buttons (assuming a person wants to maintain strict Neo-Geo compatibility).

I'm wondering how terrible it would be to design an otherwise completely Neo-Geo compatible, 8-button controller pinout that used the outside of a DB-15 connector (usually reserved for ground) as a signal-carrying connection.  This signal line would be used for that last button (unused by the Neo Geo).  I want something along the lines of the Super Neo Geo Controller Pinout with 8 buttons so that the stick will work for the PlayStation, Saturn, etc., as well as with the Neo Geo AES, CD, and MVS.

It would seem that wiring this way would still allow for compatibility with Neo Geo controllers, since they use pin 1 for ground.  I do realize that there may be some problem at the machine end, since I can't verify that the outside of the controller connectors on the Neo Geo AES and Neo Geo CD systems aren't conductive (although I do know that the outside of the controller connectors on my MVS model MV-1 are plastic).

Again, I don't want to do this.  I know that this would go against a very basic wiring convention.  I know that it would increase the risk of short-circuits, but I just can't think of another way to design an 8-button controller pinout that would still be compatible with standard Neo sticks and pads.  Sticks utilizing the controller pinout I'm imagining would potentially be compatible with mainstream console systems (through a converter/encoder), the Neo Geo AES/CD/MVS, and SuperGun arcade-board systems.

Am I spouting blasphemy here or would this be a reasonable course of action?

[NFG]

It's a bad idea, but not hugely bad.
1. The outside is usually connected to the cable shield mesh, to prevent RF interference.
2. The outside pin is wide open to contact from any random metal thing flying about your house.

Just ignore the second D pin on the neo and you'll have enough pins for all your buttons.

[martianviking]

It's a bad idea, but not hugely bad.
1. The outside is usually connected to the cable shield mesh, to prevent RF interference.
2. The outside pin is wide open to contact from any random metal thing flying about your house.

Just ignore the second D pin on the neo and you'll have enough pins for all your buttons.

Yep; that's the way I saw it.  I don't like it, but I don't see any other way.

4 (standard Neo buttons)
+1 (outside connector, risky)
+1 (duplicated "D" pin)
+2 ("NC" pins 2 & 10)
==========
8 total buttons (enough for about any console)


EDIT:  Another thing to note is that just because a controller is wired with a button that uses the outside of the connector as its lead, you don't have to wire your system (or controller converter) that way.  On a system or controller converter that only needs seven or fewer buttons, just wire the outside of the connector as ground and you should be perfectly safe (since that eighth button will just short ground to ground).

The only systems that should actually be put at any risk would be PlayStation, Xbox, N64, and Saturn systems.  The SNES, GameCube, Genesis, Dreamcast, TurboGrafx/PCE/Duo, Neo Geo AES/MVS/CD, and SuperGun systems should all be able to live (in blissful ignorance) with a controller that is wired this way.  And, if I am not mistaken, shorting the outside of the connector to ground on a PS2 or Saturn system would hopefully just activate the eighth button rather than do any damage.  Yes, it is opening the system up to a risk (if that signal gets shorted to something other than system ground), but it should be manageable.  (And I still don't see another way to squeeze that eighth button into a Neo Geo compatible DB-15; the only other way would seem to be a one-button "kick harness" sort of secondary connector for PlayStation/Xbox/N64/Saturn systems, and I just don't know if that would be realistic.)