# MTS and DCC and DC track polarities?



## Jerry McColgan (Feb 8, 2008)

OK. LGB G Scale analog track polarity is reverse from NMRA and Lionel G Scale follows NMRA standards (Lionel locos run backward compared to LGB, Aristo and USA locos). 

To keep harmony on my layout I have reversed the analog track polarity of my Lionel locos to match my LGB locos. So much for analog track power. 

Now for MTS and DCC... 

When connecting a decoder to the track contact wires for use with MTS/DCC - when the locos will continue to be run primarily on analog track power - should the decoder be wired to the track contact polarity as per the (non-LGB) decoder instructions or will that result in the loco running with reversed polarity when back on track power? 

In other words do LGB and Massoth use the same track polarity with their decoders for MTS/DCC as all other G Scale decoder manufacturers? 

Thanks, 

Jerry


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## rwbrashear (Jan 5, 2008)

Jerry- 

The answer is... 

Don't hurt your brain thinking about it too much. Before you close the loco, test it on an analog and digital track. 

If the loco runs backwards in analog, reverse the track power leads. 
If the wrong directional lamps are illuminated in digital mode, reverse the motor leads. 

(I am assuming you wired the directional lamps correctly. ) 

Find the polarity that works and write it down. Laminate it. Keep it in your wallet. Make extra copies to hide in drawers (for when you lose your wallet). 

Best regards, 
Bob


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## Jerry McColgan (Feb 8, 2008)

deleted


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## Jerry McColgan (Feb 8, 2008)

deleted


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## rwbrashear (Jan 5, 2008)

Jerry- 

You wrote: 

As I used to tell my high voltage seminar attendees: 

"You can do it right the first time and thus only have to do it once or... 

You can do it wrong the first time and TRIPLE your work because now, before you can do it right, you have to first undo your screwup." 

I think that is why they print instruction sheets. 



I thought reading instruction sheets was against your personal value system?  

You are funny. If I had given you a protracted reply, explaining the differences between NMRA wiring and LGB wiring, you probably would have told me that my answer was too complicated and the "trial and error" method was easier. If I provide a simple, efficient, and practical method of getting the wiring correct, well, you tell me that I am tripling your work. 

There is a slight difference between connecting three phase high voltage lines and connecting a few 22 AWG wires. Did you ever think of using insulated alligator clips or small wire nuts to hold the wires together as you test? Believe it or not, this takes a little less time than braiding high voltage cable. Remember, if you document the results, you only have to perform this process once for each motor and decoder combination. If you are installing 20 DG583S decoders into LGB starter set locos, you will spend ten minutes getting the polarity correct on the first installation, then you will replicate the same wiring 20 times. I really don't see the big deal. 

Of course, if you enjoy playing devil's advocate with responses to your questions...  

Best regards, 
Bob


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## Jerry McColgan (Feb 8, 2008)

It is as basic as VISUAL VS TECHNICAL. 

The reason I started this topic was clearly stated: 

"In other words do LGB and Massoth use the same track polarity with their decoders for MTS/DCC as all other G Scale decoder manufacturers?" 

All I was looking for was whether Digitrax uses the same left and right track contact polarity for their decoders as LGB and Massoth use for their decoder track contact polarity. 

It is a FACT that Lionel and NMRA polarity specifications ARE THE REVERSE of LGB track polarity. 

It is also a FACT that MANY people (like me) learn best by VISUAL information while others learn best by WRITTEN data. Manufacturers understand this which is why they provide pictures, diagrams and schematics as well as written instructions and manuals. 

I work best with reference to VISUAL SCHEMATICS. It is difficult for me to learn from written technical information. 

When it comes to my trains I am a MECHANIC (installer). I am NOT AN ENGINEER. My training in understanding electronic circuits was 45 years ago (when vacuum tubes were common and transistors were relatively new). That knowledge has not been refreshed, updated or used for at least 40 years . I duplicate and install things that others have designed and or engineered to be installed by people who do not fully understand how they do what they do but just how to make them do what they want them to do. 

If someone talks to me as one engineer to another engineer, they should not be surprised if I do not understand or follow their advice. 

If someone really wants to help me they should talk to me as one mechanic (installer) would talk to another mechanic (installer). 

I am not trying to engineer or design anything. I am trying to install the same exact things that thousands of others have installed before me. 

I simply want to know how someone else previously did what I am doing and I prefer to do as little computer (decoder) programming as possible. 

I have no desire to learn any more about decoder programming than the very minimum I have to know to make a decoder act the same as it does under analog track power - but to so with multiple operators. 

I don't have to understand how schematics work - just where to put the resistors, diodes and capacitors - and which ones to use. 

I also don't need to learn everything about all the CV's a decoder has. I would much prefer someone to tell me to change CV (whatever) to whatever the setting I need should be. 

Jerry


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## rwbrashear (Jan 5, 2008)

Hi Jerry- 

You wrote: 

Why are we in (yet another) long discussion and you are now accusing me of playing devil's advocate when you are the one who never bothered with giving me a simple YES or NO answer? 



I thought we had moved beyond the fact that all largescale loco and decoder manufacturers don't necessarily follow the same wiring protocol. LGB and the NMRA march to different drummers. Since this is the case, my advice was designed to give you a simple method of wiring your locos for analog and digital control. To be honest, it is a lot more helpful than stating 'yes' or 'no' could have been. 

You wrote: 

I am also 6' 5" tall and 325 lbs and I have BIG HANDS and my eyesight is not that great. 



Okay. I give up. You got me. I am not sure why your height, weight, hand size, and eyesight are relevant. I understand the "big hands" part is certainly important, as you chose to emphasize the text, but otherwise I am in the dark. Sorry. 

You wrote: 

Show and Tell defines precisely the sort of information I am looking for each and every time I post a question just as Show and Tell defines precisely the sort of information I offer to others whenever I post on a forum. 



We are getting further from the topic, but since it is your thread... 

To be honest, a picture of an assembled loco isn't very helpful, nor is a picture with a pile of tangled black wires. Still, it is nice to see pictures in posts. 

As for other 'show and tell,' I find it odd that you prolifically post Herr Koopmann's work and the full text from the copyrighted LGB Telegram. This is certainly a bit disrespectful of Frances and others that copyright their intellectual property. 

Best regards, 
Bob


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## Dwight Ennis (Jan 2, 2008)

I suggest you two take your personal feud to email. Thx.


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## Treeman (Jan 6, 2008)

I just think Jerry likes to type, I wish I could do as well with little fingers. 

Jerry are you going to make it to Marty's


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## Jerry McColgan (Feb 8, 2008)

I had planned on going to Marty's but it is so close to the MWLSTS I will probably just go to the MWLSTS this year. It would just be too many miles in too little time for me. 

Jerry 


Posted By Treeman on 08/01/2008 9:35 PM
Jerry are you going to make it to Marty's


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## Greg Elmassian (Jan 3, 2008)

I had the same conversation with a friend today about "polarity"... he runs DC and DCC.... 

When I told him what to do if the loco runs backwards on analog (reverse the motor leads to the decoder and reverse the track pickup leads to the decoder) it threw him for a loop. 

I think the issue is getting someone to "unwrap" himself from thinking about "polarity" on DCC... It's apparently difficult to do in some cases. 

Maybe this will help: 

Take a loco and put DC on the tracks and place the loco on the track so it moves forward.... now pick it up and turn it end for end, it now runs backwards.. 

reason: reversing the polarity of the track pickups reverses the polarity of power sent to the motor. 

Now take a loco on DCC... COMMAND it to run forward. it will... 

Now take that loco and swap it end for end... it STILL runs forwards... 

Reason: the track "polarity" is irrelevant to a DCC decoder... 

So, you can do things like rewire the loco to run in a different direction on DC ... WITHOUT affecting DCC motion (swap track input to decoder) 

You can make the loco run in a different direction on BOTH DC and DCC.... (swap motor leads) 

You can make a loco run in a different direction on DCC but not affect DC (swap motor leads AND swap track leads) 

You just have to think about it... swapping the motor leads affects all operation DC and DCC 

swapping the track leads affects only DC. 

I don't know if it helped, but it's basically what Bob stated, but stated in several permutations, but from the same "rules" he stated. 

Regards, Greg


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## Jerry McColgan (Feb 8, 2008)

Hi Greg, 

I think you are right in that for someone like me who is used to the "comfort" of DC polarity it is confusing to try to "unthink polarity" to work with both DC and DCC on the same loco. 

In my case I tried the proven method of swapping one lead at a time until (I thought) I had tried all combinations (not hard when there are only four wires to work with). 

I was mistaken - I had apparently not tried all combinations because strangely the LGB locos ran right but all three Lionel locos I wired ran backwards in DCC. I had repeated my mistake three times with Lionel locos and never with a LGB loco. 

What worked for me was to remember that with DC if the loco was running in the right direction under DC there was NO CHOICE - if I swapped the track lead - I HAD to also swap the motor lead because under DC if I swapped one but not the other there was no way that the loco would not change direction under DC polarity. 

The solution for me turned out to be pretty simple - and will be easy to remember in the future: 

1. FIRST - get the loco to run in the right direction under DC (analog track power) because (for me anyway) this is the easiest thing to do. 

2. Next - if the loco also runs in the right direction under MTS/DCC you are done. 

3. Finally - if the loco runs right under DC but backward under MTS/DCC - REVERSE EVERYTHING - and it will work and you will be done. 

Track leads must remain track leads but must be reversed. 
Motor leads must remain motor leads but must also be reversed. 

The more I originally thought about it the more confusing it became. 

I finally realized that DC is inflexible in that once the positive track lead was connected to the correct motor lead to make the loco go forward I could change which side of the decoder I could plug them into but I could/should not change their polarity with each other. 

A person accustomed to finding the correct DC polarity for his locos can still use that knowledge to wire a DCC decoder once he realizes that he can swap everything for the left rail with everything for the right rail and still have maintained his original polarity. 

It is perhaps less a case of who or what solution is right or wrong (they all probably work equally well) but rather finding a way that makes sense to each of us. 

Regards, 

Jerry 



Posted By Greg Elmassian on 08/06/2008 11:11 PM
I had the same conversation with a friend today about "polarity"... he runs DC and DCC.... 
When I told him what to do if the loco runs backwards on analog (reverse the motor leads to the decoder and reverse the track pickup leads to the decoder) it threw him for a loop. 
I think the issue is getting someone to "unwrap" himself from thinking about "polarity" on DCC... It's apparently difficult to do in some cases.


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## Road Foreman (Jan 2, 2008)

Guys, 

DCC decoders are designed to meet the NMRA standard.. This is plus on the engineers side to make the loco go forward.. If you install a decoder in a analog loco, the decoder has to be installed so that when it is on DC & plus is on the engineers side the loco will go forward.. 

BulletBob 

PS In the UK it is negative on the engineers side..


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## Jerry McColgan (Feb 8, 2008)

BulletBob, 

Are you serious? 

If I took a decoder equipped loco to the UK it would run backwards under MTS/DCC? 

I knew the Brits refuse to drive on the right (and correct) side of the road  but I never imagined they would mess with my genuine American (well OK - German) locos. /DesktopModules/NTForums/themes/mls/emoticons/hehe.gif 

Gee Whiz!!! 

Perhaps that is why it is not called the INMRA?  

Jerry 


Posted By Road Foreman on 08/07/2008 8:29 AM

PS In the UK it is negative on the engineers side..


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## Road Foreman (Jan 2, 2008)

Jerry, 

There diesel drivers set on the left side of the cab, opposite to our diesel drivers who set on the right side.. They normally only have a engineer & no conductor.. The engineer gets blamed for every thing, no body else to point the finger @.. 

BulletBob


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