Amiga joysticks autofire circuit for an arcade cabinet

[D]

I have an old quickshot Amiga joystick that I want to hack for the autofire circuit to be used in my cab.

Amiga joypinout
http://www.technick.net/public/code/cp_ ... _mouse_joy

My problem is the 50mA max
The 5 Volt that the cab provides has too much Amperes right?
What should I do? Is there somewhere I can tap 5V that has the required mA?
What would happen if I fed the 5 Volt from the cab to the joystick? It would probably fry the autofire circuit right? I am looking for a quick and dirty solution is there is one. what parts can I use to bring the mA down? how much mA does an average cab output?
Someone once told me that most devices just take the mA they need and that the rest just goes back?

any tips?

[Pingu]

What they mean there is that you can't pull more than 50mA through it, as in don't hook up a jamma board through that tiny little wire. Just hook it up to 5V no problems.