# Engine block wiring - USA S4



## JackM (Jul 29, 2008)

It is time to throw in the towel and ask for help.

I'll spare the details. What it is is I was about to install some polyswitches in my trusty S4, once the season was over. When I opened it up, I was dismayed to find a few wires with melted insulation, so I started to re-wire the engine blocks. I think I have a decent understanding of the wiring for any standard DCC decoder, no big deal. I removed the sound card, disconnected the lighting and proceeded to get myself plenty confused. I have printed instructions that make it very clear, and I've done it a few times, with my other engines.

1 - a few weeks ago, somewhere around this place (I think), I saw a diagram of *wiring for the USA block*. My web searches have been unsuccessful in locating it. Anyone know where that might be?

2 - The printed decoder instructions I have say "there should be no continuity between any track pickup wire and any motor wire". I have driven myself crazy (admittedly a short drive) connecting this wire with that, but I can't find a combination that doesn't get me a reading of about .9 ohm somewhere between motor and pickup. Not surprisingly, powering up the NCE gives me a slow blinking power LED, indicating a short.

I used a new set of mini-alligator clips to try every possible combination, but I can't eliminate that .9 ohm reading, and can't get the NCE to move in other than quarter-inch jerks.

Where can I be getting this short? Presuming I can get the wiring right, what could be causing this short circuit? I haven't found any stray piece of wire, etc.

Your suggestions will help in the search for my dwindling sanity.

JackM


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## Dick413 (Jan 7, 2008)

did you unplug the wires from both motor blocks and check them one at a time for the short? here is a site that shows the wiring for a s4 it is for rewiring to bat. but tells what the wires are for. http://ovgrs.org/the-trains/battery-power-radio-control-and-sound/usa-trains-s-4/ and you might try here http://www.elmassian.com/trains/mot...t-motive-power/usat-quick-a-dirty-dcc-install


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## JackM (Jul 29, 2008)

Dick - Thanks for these two references. The Ottawa club page has to be the most detailed instructions about power installation, although all that "battery stuff" might confuse me. But there's a lot of discussion regarding the inner workings that might help. Greg E's S4 page is where I got my information when I was first learning about decoder installation; I didn't notice his "Quick & Dirty" page before.

All this info will help me settle down a bit. With a little luck, once I re-wire the S4 the way it was, there might be a hint as to how I'm getting that short. Thanks.

JackM


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## Greg Elmassian (Jan 3, 2008)

Dick has it exactly, you need to disconnect the wires first because the stock wiring connects the rails to the motor (and main board).

The quick and dirty works for many people.

I have 550 pages on my web site, but you should read "top down"... ALWAYS read the main section on the manufacturer, before diving down into the specifics of a model, I can't (and won't) repeat all the "general" information in each specific model page.

Notice under USAT motive power, (after reading that page please) the first menu is "split axles" and the second is "quick and dirty".

It's there, but it's a constant issue for me, because many people want the quick answer first, there's a lot to learn about this stuff, that's how it got to 550 pages 

Regards, Greg


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## JackM (Jul 29, 2008)

Ho boy, stuff I should've seen coming.

I bought a new bunch of alligator clips today. What I should've bought was a new set of probes for my VOM. Never in my life had to replace probes. But then, this is a VOM from, uh, Harbor Freight. Turns out I actually did get what I paid for.

The other thing points at just what you're sayin', Greg. I have long marveled at the length and breadth of your website, and I can understand that you don't want to be a slave to the site. G-guagers of all levels are grateful to you, Ted Doskaris and others for all the help contained in your site. This "other thing" that I discovered just a few minutes ago is my misinterpretation of a phrase in your S4 page regarding which pin does what. All this time I've been afraid that the wires at each end of the truck were hardwired into their positions, so I didn't want to wiggle them too much. This afternoon, I took notice of the word "pins" and summoned up the courage to grab my needle-nose pliers and disconnected the outer wire and discovered that the inner 2 pins are to the wheels, not to the motors. Well, there's the short! I'll bet I have the S4 rewired and running tomorrow. Nothing makes you feel like you learned something like a three-day fight for the knowledge.

Like your last sentence above, I wanted the quick answer (always do). Lesson learned.

JackM


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## Greg Elmassian (Jan 3, 2008)

Good for you Jack, sounds like progress. You would "logically" think that the outer 2 pins would go to the wheels, but NOOOOOO.... threw me for a loop the first time until I took the blocks apart and looked inside.

Yeah, I understand human nature, but cannot make each page a tutorial. You can imagine the mail I get. I wish I could make a menu structure that "leads you by the hand" a bit more, but the upkeep of the site is a lot of work and I add something almost every day.

Regards, Greg


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## Dan Pierce (Jan 2, 2008)

Most LGB and USA trains have the outer power pins for motor and inner pins for track.
However the FRR engines (Chloe for one) have the outer pins for track and inner for motor. And USA motor blocks need track and motor cross wired whereas LGB just short adjacent pins together for correct direction on DC.


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## JackM (Jul 29, 2008)

Guys - thanks for your help, suggestions, advice, etc. The S4 is rewired and everything's working again, including my remote control Kadees (Phoenix board). Gave it a lube job while it was up on the rack, too.

Life is good in Hooterville once again.

JackM


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