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'Ghost' Key Presses

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Klomper:

I have almost completed my conversion of a nonworking NARC to Mame (will hopefully update my project page soon), with everything up and running and just doing some final setup and cleanup.  In the testing I have found that I am getting some ghost key presses. I had this almost identical setup in a 'temporary' panel for over a year and never had a problem. ???

I hoping people can point me in the right direction of what to check so I don't waste to much time trouble shooting.

Here is hopefully all the relevant information
1. IPAC-2 PS/2
2. 2 joys/w 7 buttons, 2x coin, P1/P2 start, ESC and Pause
3. Happens at least one time a game in 1942 (random loop) or other shooters where a bomb is randomly released. Did not notice a problem in NBA Jam or TMNT.
4. Windows XP
5. Stripped CAT 5 for the wiring (new to this setup)
6. All noticed random presses have been P1 B2 except one time it was Pause.

So far I have:
1. Resaved my configuration to the IPAC
2. Made sure P1 B1/B2 wires did not have contact.





miles2912:

I would go through the checklist here and see if it helps.  Towards the bottom of the page is the troubleshooting.

http://www.ultimarc.com/ipac2.html



ultrageek:

I wonder if the tristed pair wiring in the cat 5 is inducting a singal into the other pair(s).
I'v seen stranger. I know that this is extremely low voltage and shouldn't be an issue, but since the Cat 5 is new to the design, it's a likely contributor to the problem

CrazyKongFan:

Isn't that why the twisted pairs in cat 5 are twisted in the first place, to prevent interference?

bkenobi:

You are not inducing a signal by a button press.  I'm not an EE, but I know that inducing a current requires a high current on the source side.  You have (essentially) 0 amps running through the buttons, so you will have 0 amps running down any other conductors.  You may have 5 volts, but it's got (essentially) no current so you can't induce with it.

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