USA SD70 Mac ( wiring digitrak decoder )

[Anonymous]

I just purchased a USA SD 70 MAC.My first USA engine purchase.
I'm running DCC the problem with USA it's not DCC ready.
I have the correct Digitrak decoder DG583S but, just a little unsure on the wiring.
I understand pin 1 left track, pin 2 motor - , pin 3 not used, Pin 4 + common (?)
pin 4 ground (?) , pin 6 not used, pin 7 motor + , pin 8 right track.

Ok, wires coming from the motors and pick ups go to pins 1,2,7,8.
Then do I run wires from those pins to the USA main circuit board?
What about pin 4 common and pin 5 ground?
Can someone one help me?
I've hooked up no problem with Aristocrafts since it's dcc ready.
I have a aristocraft with sound that I did.
Sound would be next on the USA SD 70. I should be fine on that. Any sugguestions would be nice.
Also is it going to be ok with the 5amp decoder? I've seen bits here and there with power drawl.