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Discussion Starter #1
I need everyone to put on their thinking caps for an issue that I have with an lgb 2-6-0 locomotive.

The loco in question had a bad motor. I know this because with almost full throttle the motor wouldn't run unless you bumped it by hand. I bought a new motor and it works fine. Well, sort of. lol

With the assembled motor block on my bench and power attached to the motor leads it runs very smoothly forward and reverse. When it is installed it will only run in reverse, smoothly like it should. In forward, firebox flickers, headlight comes on but no motor. Where should I look to solve this problem? three of us are scratching our heads over this and wondering if we missed something obvious. Would a bad board cause this issue?

Thanks for your help, I check in periodically during the day so bear with me if I don't respond right away.

Bill
 

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It maybe best to quote the model number as there were quite a few different models.
I know there were differences in the wiring for the digital sound ones.
Is it 2018D Red and green Number 18? I have the same.
Or 21181 Black boiler Number 19?

Andrew
 

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Try testing it on it's side touching the wheels with some wires then do the same on just the contacts.
Do you get the same result as on track?
Does the rear tender light work when plugged in and running in reverse?

Andrew
 

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Something is very strange, like a miswire of the motor on the wrong side of a diode for directional lighting.

Is this a 3 wire or a 4 wire motor block?

Greg
 

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Looks like a 3 wire block, so there would have to be a diode between the 2 wires that are switched with the motor on off switch.

The diagram suggests that the 3 wires go directly to the tender plug, but they must go to that #49 part since that is where the headlight and smoke unit connect.

Does this loco have the slide switches for lights and motor and smoke on off?

Greg
 

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Tender plug on LGB 3 wires to the tender have 2 track power wires and one wire for the rear light on coal tenders.Rear light references one track wire for the light!!. (Wood tender has no light but does have the wiring).

Motor block has 3 wires, one rail is tied directly to the motor, the other 2 are for the rear switch should be on highest number (all the way to the right as viewed from the tender).
 

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Discussion Starter #10
First off, thank you for the responses. The loco is a model #26194. The motor block has a four prong, flat plug that can only be installed one way. I have determined (I hope correctly) that the out side leads go to the motor and the inside two are from the pickups to the circuit board.

Garratt: With the assembled motor block on the bench applying power to motor leads it works fine, forward and reverse. After installation it only works in reverse, although the front light and boiler lights work fine come on when in forward mode. No hum, no motor noise, nothing from the motor.

By the way, reversing the motor in the block will allow it to run forward, but not in reverse with the lights coming on opposite of the motor direction as expected.

I hope this helps. Thinking out loud, I wonder if testing the motor plug might help. Applying power to the pick up side and then reversing polarity, simulating a direction change for the motor. If polarity reverses, or not, it might tell me if the problem is elsewhere. Hmmmmm......suggestions?

Bill






Bill
 

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It's got to be in the electronics, since you have proved the 4 connections to the motor block work.

In the "4 wire" motor block, the track pickups and the motor pickups are all isolated from each other. So since the motor runs, both motor wires in the block are fine. Since the loco moves on the rails, both track pickups are fine.

So somewhere there is a diode between one of the track pickups and the motor. I was under the impression that the motor on/off switch was a single pole single throw, or a single pole double throw, so it should only be interrupting one "side" of the motor connection.

Something is really strange. You can try applying power to the motor plug (wires from the motor block), but I'm pretty sure that part is ok.

Greg
 

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Discussion Starter #12
Greg,

I tend to agree with you. I hate being a "parts changer" type of mechanic and like to accurately diagnose the problem before buying parts. What you suggested about the electronics was my gut feeling but I wasn't sure.

Bill
 

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Does the motor control switch actually enable/disable the motor powered from the track (test in the direction it runs of course)

That might give a clue.

Greg
 

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26194 is a digital with digital sound in the engine, wires going to the tender are:
2 for track power
2 for rear light
2 for speaker.

It could be the MTS board needs a reset, cv 55 to 55.

If you are analog only, this reset can not be done.
Also if you have pulsed power of any kind the decoder may act strange.
 

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Discussion Starter #16 (Edited)
Dan,

Its always good to learn. Mine has the six wire plug as described. Now I need to figure out how to reset the board. I'm analog only. ugh!
 

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Join a club in Vegas and someone there should have a DCC system and can do the reset.

Or, if you know how to take the engine apart, you can send the board (actually the metal plate with both boards, bottom board is sound, top is DCC.to me to check it out.

I have fixtures to test out the LGB onboard decoders like the one in your engine.
 

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On another note, the DCC decoders can turn off analog operation with CV 29. The reset will turn analog operation back on. Again, setting CV 55 to 55 will reset the original LGB mogul decoder for analog operation.
 
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