# USAT S4 Electronics Questions



## MaineCentral (Feb 10, 2015)

Hello Everyone!


I am currently gutting the electronics in my USAT S4 and as I was doing so I noticed something that I wasn't sure it looked right. The front and rear motor block connectors have black and red wires and both were reversed from the PCB connector colors. Red to black/black to red for both motors. Is that right?











So here is where I am now, stripped down and ready for Air Wire and battery power. Now I have read somewhere there is an issue with reversed polarity on USAT lights also?










I removed the smoke unit and it's board, the power pickup sliders and their wires.


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## Dan Pierce (Jan 2, 2008)

Yes, the colors need to be reversed as the motor blocks have wiring in opposite directions due to the fact that the wiring always faces the center of the engine.

So one block is backwards from the other.

Also note that the track connector has 4 wires as the shoe has a separate wire, and the motor wire connector is 2 wires.


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## Dick413 (Jan 7, 2008)

Yes to usa wiring it is easier to give you a link than to try and tell you http://www.elmassian.com/trains/motive-power-mods-aamp-tips/usat-motive-power/s4 read the bottom on the lights


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## MaineCentral (Feb 10, 2015)

Thanks Guys!


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## Greg Elmassian (Jan 3, 2008)

This configuration allows the 2 motor blocks to be identical, since one runs "backwards" a polarity reversal must be somewhere in the circuit.

Greg


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## MaineCentral (Feb 10, 2015)

Thanks Greg

I've been spending some time at your website...it and you are always very helpful, thank you! 

I have everything wired in EXCEPT the lighting situation. I have not connected any of that. When I figure that out, I will be done!


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## Dan Pierce (Jan 2, 2008)

If the engine has dual colored led lights, they are common cathode. I change them to brighter common anode as Decoders ground a cathode to turn on a led.


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