Phantom Left Alt presses on IPAC4 in USB mode

[davieboynj]

I waited so long on posting this one because i figured that i just had a wiring problem, but i rewired all three of my control panels and still no luck.  Anyways...

Especially during the button mashing marathons of bubble bobble and ghouls and ghosts, I routinely get the involuntary jump, often resulting in death.  When i switch the game settings so that Left Alt is button 1 and Space is button 2 i have no problems. 

Shamefully, the problem reared its ugly head most embarrassingly when a couple of friends were over and wanted to play a little bit of "moonwalker".  MJ seemed to dance uncontrollably at the most inopportune times.  What kind of self respect is a man to have if he can't keep michael jackson from dancing in his own house? 

relevent specs:
windows xp
ipac4 in usb mode (non-programmed)
command line mame .104
windows wireless keyboard (seems to have no bearing on problem)

[ahofle]

I waited so long on posting this one because i figured that i just had a wiring problem, but i rewired all three of my control panels and still no luck.  Anyways...

Especially during the button mashing marathons of bubble bobble and ghouls and ghosts, I routinely get the involuntary jump, often resulting in death.  When i switch the game settings so that Left Alt is button 1 and Space is button 2 i have no problems. 

If you are sure it's just that one button (and you double checked all your grounds), then it could be a bad microswitch.  I had an issue with microswitch 'bounce' and replacing the cherry switches solved it for me.  Try swapping out the switch from another button just to test it out.  Also, put the suspect switch on another IPAC input like 'space' or 'Z' and open up Notepad and see if you can get it to happen there.

What kind of self respect is a man to have if he can't keep michael jackson from dancing in his own house? 

I'm afraid any trace of self respect you may have had is now gone due to playing Moonwalker. 

[davieboynj]

... it could be a bad microswitch.  I had an issue with microswitch 'bounce' and replacing the cherry switches solved it for me.  Try swapping out the switch from another button just to test it out.  Also, put the suspect switch on another IPAC input like 'space' or 'Z' and open up Notepad and see if you can get it to happen there.

that's a really good idea.  I didn't move the switch, because i want to keep it as tightly controlled an experiment as possible, but i mashed away on button 1 (LCTRL) with focus on an explorer window.  if button 2 (LALT) was ever phantom triggered, the ALT (file) menu would have become highlighted.  It never did.  Very bizzare.  I ran out of time, but tomorrow i'm going to replace the microswitch with another and see if the "bounce" is creating the problem.  From there, i guess i'll just move around some inputs and see if i can't get this thing 100%

thanks for your help!