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EMD F9 Question (wiring)

4733 Views 8 Replies 3 Participants Last post by  T-Man, 
M
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This is the Santa Fe F9 I refered to a few months back. The Large red and Black wires are the ones that disconnected from the engine. The diagram it sets on in the photo shows these wires going to the Contact plates on either side of the train yet does state or show which. Also is there a need to remove the retainers to do this? I fear i may bend them if I do. If anyone has a truck system that you can peak at, would you take a look? Again it's the larger of the four wires, and they do go under the plastic truck guards. This is fairly difficult to take apart, so pleae if you have one you have not done this to, please don't on my account!
Also with it being an older style using box style connectors for car hookup, is there a certain coupler i need to buy to upgrade to the horn style on my new cars? I intend to use this locomotive for the yard engine in my grainery. I think it may look odd as a backup engine with my duel Engines.

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tjcruiser
Mit,

Can you post a larger (higher res) pic of the open loco and (separately) a pic of the wiring diagram, perhaps?

TJ
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tjcruiser
Mit,

I'm no expert here, so take all of this with a grain of salt ...

In viewing the wiring diagram, it looks to me like your loco has a pretty simple setup. As you know, HO runs on DC, with one rail acting like a Positive terminal of a battery, and the other rail acting like the Negative terminal of a battery.

Some diesel locos have their Positive pickups on one truck (say the front), and their Negative pickups on the other truck (the rear, in this example). It looks like your loco has BOTH positive and negative pickups on EACH of the trucks. I'm not really sure why that's needed, other than to help the loco navigate through local small dead spots in way of switches / turnout. Regardless, if this is the case, then the front truck needs to be wired in parallel with the rear truck ... i.e., positive to positive, negative to negative, or ... right rail to right rail, left rail to left rail.

In addition, your rear truck has a separate pair of wires (also in parallel) that go forward to your light.

I hope this is consistent with what you're seeing by looking at the actual loco. My comments are based upon the wiring diagram, only ... your pic of the loco is really too small to see any details.

Hope this helps,

TJ
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tjcruiser
Ahh,

T-Man's comment lit a lightbulb in my head ...

The contact plate detail shown in your wiring diagram (echoing the photo above) is a detail of the FRONT truck, not the rear truck, as you have drawn in red ink. Makes much more sense ... power from the rails goes through the front wheels (insulated left to right, per T-man), then via wires to motor mounted on rear truck.

TJ
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tjcruiser
Mit,

I suspect you're misinterpreting the diagram. The "detail view" that shows the contact plate assembly (at the pointy end of your red arrow) likely exists in the FRONT truck, only ... NOT the rear truck. These are the electrical contacts that touch the wheels which grab power from the track. From there, 2 wires run aft to the top of the motor -- the 2106 assembly that you see in your red circle. Those wire go into the "brush contact springs" 1881-3.

So, to "jump start" your motor, you can run a pair of +/- wires from your track (or transformer) to either:

a) the broken wires that should (but don't) run from the front truck to the rear truck, or

b) directly to the 1881-3 brush contact springs, if you can see them.

In terms of which broken wire should go where (when you resolder them), it simply a matter of train direction. One way will yield forward, the other reverse ... which you can toggle at your transformer, too.

T-Man ... do you agree on thoughts above?

TJ
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