# EMD F9 Question (wiring)



## Mit (Feb 12, 2010)

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 (Jan 10, 2010)

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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## Mit (Feb 12, 2010)

Nope can't do it )scan 1 shows the document of the wiring, emd9 shows a better photo of the back track trucks where the wires go but crappy instruction on where really.
hwell:


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## tjcruiser (Jan 10, 2010)

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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## T-Man (May 16, 2008)

The motor needs two leads to run, one to each rail. You need the wipers to touch the wheel s/axle. The units may snap of from the bottom. What brand is it? In your case the motor is on one truck with rail contact on the other. Pretty normal. One wheel is insulated on the axle. Make sure the alignment does not short out your circuit.


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## tjcruiser (Jan 10, 2010)

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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## Mit (Feb 12, 2010)

i know the photo isn't very good i have to transfer from camera to paint then reduce to meet requirements for posting, let's see if this helps any. The two broken wires (1 red 1 black) come from the front axle to the rear. the other two leads for the light, come from the top of the rear axle hookup. In the diagram it shows the the broken leads connecting undr the brass plates that run from center to both wheels. However these don't seem to have a clip to remove them, it does have a very tiny circular "button" clip on the center of three plastic posts. (which i know are gonna break if i attempt to remove them) And i cant see any spots where solder was ever applied near them, no flux marks like the others anywhere near the diagrams photo. That is what is confusing me. It's a Bachmann (china) locomotive, unfortuneately no date stamp but i know i have had this engine for nearly 20-25 years at least. In a pill jar i have 2 contact plates a spring and a contact pillar, but none are in the blow up  I may just have to try rummage saling to see if i can find another to examine. If u look closely at the diagram one shows the wires connected at the top the other at the bottom the one labeled 2106 is the one that looks like mine not the 1996-1 one but this is what is confusing me. So do you think i should just try a spot touch test and see what happens? I guess if it burns up i can use it as a dead loco, not that i like the smell of burning trains lol.


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## tjcruiser (Jan 10, 2010)

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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## T-Man (May 16, 2008)

I'll get back with some Bachmann pictures.
I can't make out anything in the pictures. 
All I can do is show one that has the parts at this point.

I picked this Tyco because you can tell which wheel connects with the track. The best way for you problem is to get another junker for parts. These engines are old and new parts are not readily available. Paint is no big deal. I use it . Just pick an easy rate .For a large I go with 12. These are M3 and I go with 23 %.


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