whats in a neogeo pad a dual inverter?

[ulao]

I have a neogeo controller with a few small chips that look like some sort of dual inverter or logic gates.  I need to replace two of them, but cant figure out what they are.  Anyone know?

[l_oliveira]

Nah ... They're just current boosters, because the NeoGeo CD uses the same I/O interface as the normal AES/MVS units and the buttons are of conductive rubber.

software wise just process the PAD exactly like you would process the original NEO GEO controller. But the PAD requires +5v to power on the button buffers. And since the AES and MVS don't supply that, the PAD connector has some "squares" on the edges to prevent it from being connected to the older systems.

[NFG]

That's not quite correct, the AES does provide +5V on pin 8 (IIRC), and the pads and bean-style sticks work just fine.

I'm pretty sure they work on the MVS as well, but I can't test that.

[l_oliveira]

Then what's the point of the "fins" which prevent insertion of the NGCD pad on a AES or MVS unit ?

Also you know that neither units need to have +5v on their controller connectors anyway. Even if they have ...

[NFG]

I don't recall seeing any 'fins'? 

All my NGCD pads are in Japan, I think.  =/

[MKL]

Then what's the point of the "fins" which prevent insertion of the NGCD pad on a AES or MVS unit ?

For a tighter fit (the new style stick has them too). The NGCD pad works just fine on the AES or MVS.

Also you know that neither units need to have +5v on their controller connectors anyway. Even if they have ...

The new style stick needs 5v just like the NGCD pad so the AES must provide 5v through the stick ports.

The ports are identical on all Neo Geo systems and all Neo Geo controllers can be used on all Neo Geo systems. I thought this was common knowledge.

[ulao]

l_oliveira, thx. I have two controllers and read them the same, To read them I just read like one reads a switches really. I look for one of the lines that are closed to common. I have always gave the controller +5 and ground needed or not. The controller in question buttons c,d and two others do not works. I tried to use a piece of wire to close the switch but that didnt work, then at that point I realized it was those chips not the buttons that was the problem.  I can simulate things by shorting one of that lead after that chip to ground/common so what ever function that chip had no longer works.  just two of them  have gone bad and I need to replace them.  Any idea what they really are ?  I'm sure "current booster' is not the proper name. Perhaps logarithmic amplifiers, Op amps,or a Power amplifier ?