You don't have that button wired on the NC (normally closed) contact do you?
Sorry, but no chance he has it wired wrong.
What he described is exactly the way the I-Pac and Mini-Pac behave.
Most people never notice because they press and release the button quickly.
If the Mini-Pac/I-Pac
didn't wait until P1 Start is released to send the keystroke, picture this scenario:
* You want to play a 2 player game.
* You already have one credit.
* You want to use a shifted function for a second coin-up.
- Action (keystroke sent -- result)
- Press and hold P1 Start (1 -- 1-player game would start using the credit that you already had)
- Press P1 Button1 (5 -- a credit is added due to the shifted function)
As you can see, the I-Pac/Mini-Pac
has to wait until P1 Start is released
or another button is pressed to determine if the player intends to do P1 Start or a shifted function.
The only way around the delayed keystroke is to use a dedicated shift input with no associated keystroke like the KeyWiz Shazaaam! or the KADE HWB.
Scott