# Need help with MTH PS3!!



## Blade765 (Dec 25, 2013)

Guys,
I'm new to the forum, and fairly new to DCS. I've got a commander remote, tiu, and aiu for my ho setup. I just got a used PRR K4 by MTH. The smoke unit didn't work. I opened it up and re-wicked it. It now smokes like a champ! Everything else works, except the motor itself. I've got a single red wire that was soldered somewhere, but I've no idea where! Can you guys help me with this? What I really need is a wiring diagram, which I can't find anywhere! Any and all help would be greatly appreciated!!!!!!!

Thanks guys!!


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## gunrunnerjohn (Nov 10, 2010)

How about an exact MTH model number? Where does the red wire come from? Trace it out and tell us exactly where it's connected. Pictures help a lot when doing this stuff.

Even the MTH techs don't get complete wiring diagrams, we have some "samples" to go from. It's usually not difficult to sort out if you have the engine in front of you. In truth, usually the wires to the motors are yellow and white, don't know exactly where the red one came from.

Are you sure this is PS/3?


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## Blade765 (Dec 25, 2013)

Gunner,
Thanks for the reply! It's a 4-6-2 K-4s Steamer (Pennsy #1737)
It is definitely PS3. model # is 80-3101-1. Pictures coming. The red wire comes off of the connector that plugs into the main board. The pics are horrible, I know.


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## gunrunnerjohn (Nov 10, 2010)

Are there three wires going to the tach reader next to the flywheel? From the position of the wire, I think that may be the right track pickup connection. I don't have any HO stuff to look at, so I'm going from pictures in my manual.

What's this bare wire, the brown one?


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## Blade765 (Dec 25, 2013)

Yes, that is in fact bare wire, but has since been soldered and heat shrunk. It was a bad connection the the plug itself that I had to repair. Its supposed to be a grey wire all the way through, but I was in a rush, and could only work with what I had. The three wires going to the motor tach reader are intact. If this is the wire you think it is, where do I re-solder it to?

Thanks for the help!!


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## gunrunnerjohn (Nov 10, 2010)

Without having something to actually look at, I'm hesitant to suggest soldering it anywhere. I don't work on many HO DCS locomotives, and I'm not that familiar with the layout. If I had it in the shop, I'd probably call my direct tech line to MTH and find out more before I connected it anywhere.


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## Blade765 (Dec 25, 2013)

Would better lit/closer images help? Like I said earlier, everything works, LEDs light, sounds work, smoke unit smokes like a champ, it just won't go anywhere when I throttle up. Thats why I'm so confused on this one. 

Thanks again for the help Gunner!


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## gunrunnerjohn (Nov 10, 2010)

Where does that gray wire go?


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## Blade765 (Dec 25, 2013)

Ironically enough, the Greg wire runs to the tach reader board on the motor. I will check the right now and make sure there is continuity between the tach board and the main board.


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## Blade765 (Dec 25, 2013)

Continuity is fine all the way from the main board to the tach board.


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## Blade765 (Dec 25, 2013)

*More pictures for you, better details*

Gunner,
Please take a look at the attached photos, maybe they can help shed some light on this issue. I just don't understand how EVERY thing functions okay but the motor itself. The one thing I noticed which I thought odd (though, I am new to this, but not tech in general).

Thanks again Gunner, you've been awesome!



















In case they don't show properly, or you want a better look, I'm also uploading them as attachments.



Sent from my Nexus 10 using Tapatalk 4


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## gunrunnerjohn (Nov 10, 2010)

The Gray wire is pin 20, which makes the red wire pin 1. Pin one goes to the right hand wheels according to my diagram.

Most of the logic (and sound) is in the tender, but I suspect they're using power from the locomotive to run the motor.

The black wire next to the red wire should go to the left hand wheels. If so, find out where the right hand wheels wiper is, that should be where the red wire goes.


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## Blade765 (Dec 25, 2013)

Gunner, 
The black wires connect to these, as pictured below, but I don't see where there is a similar looking location for the red wire. So confused at this point, and frustrated. Are you sure there shouldn't be red and black (positive and negative leads) running to the rear solder points on the can?

Gunner, you've been a trooper dealing with my idiocy. I thank you many times over sir!



















As before, I'm uploading these both inline and as attachments. 



Sent from my XT1080 using Tapatalk


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## gunrunnerjohn (Nov 10, 2010)

As you know, the left and right hand wheels are insulated from each other. One set of wheels obviously has to have a wiper to transfer power from the track. Wherever that wiper connection is in the locomotive is probably where you'll find the place this wire came loose from. I don't see anything in those pictures that looks like the connection.


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## Blade765 (Dec 25, 2013)

That's where I'm getting confused. Those negative (black) wires are connected to four little spring loaded pins, two on each side. Those pins contact to the negative pickup sites. The next the I'm going to do when I get home is reassemble the entire engine, power it up and see exactly what works and what doesn't. I'm also going to see if there is actually any juice on that damn red wire. Aside from that, is there anything else you can think of that I could look into?

Thanks Gunner!

Sent from my XT1080 using Tapatalk


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## gunrunnerjohn (Nov 10, 2010)

There has to be a similar connection for the other side's wheels. Pin 1 on that connector goes to the wheel pickups as does pin 2 on the opposite side.

Try measuring right from the wheels to the black wire and see which side it's connected to. Then on the opposite side, measure between the wheel and any possible connection point and find out where those wipers are connected.


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## Blade765 (Dec 25, 2013)

The black wires run to two pins on each side for a total of four. But that is the problem, there are two negative pickups on each side. So I'm more confused then I was before. 

Sent from my XT1080 using Tapatalk


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## gunrunnerjohn (Nov 10, 2010)

Well, I'm confused. HO locomotives have the power feed from opposite sides on the wheels, so there has to be a place to connect that wire. I suspect I'd have to see this one to figure out where the wire goes.


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