OK, with the clarifications, it seems that the DCC decoder in the locomotive is sending the motor the same polarity no matter what you intend.  That decoder is between the electric motor in the locomotive and the track, with a bridge rectifier between the track and the decoder.  So, no matter whether there is AC or DC on the track, and, if DC, no matter which rail is + and which is -, the decoder always sees the same DC power polarity as its input.  It needs to determine which wire from the decoder to the electric motor gets the + and which gets the minus, based on programming in the decoder and maybe programming in the MRC controller.  It is possible that the 2 are not completely compatible, or maybe one or the other is malfunctioning.

I really don't understand how the MRC Tech 6 is designed.  It would help to know what is really happening when you push the direction buttons on the controller.  Do you have a voltmeter?  (You really do need one to work in this hobby, but it can be a simple. cheap one - you don't need a special DCC meter, even when using DCC.)

If/when you have a voltmeter, measure the voltage across the rails as you increase the throttle.  In a normal DC controller, it should  go from zero volts to about 12 volts on the DC scale.  With it somewhere in the 10 to 12 volt range, push the direction buttons and see if the polarity on the rails changes.  For a regular DC controller, the rail that is + should become - and the rail that is - should become + to change the direction of a DC electric motor that is directly connected to the rails.  Knowing whether your controller is actually doing that will help us to figure out what is happening.  Most DC controllers use a simple dp/dt slide switch to change the rail polarity.  Because your controller has buttons and is designed to send some DCC sound signals to sound decoders, I am suspecting that those buttons might do things differently.

Another question is whether you bought the locomotive second hand.  If so, it is possible that the previous owner had changed a CV (configuration variable) in the decoder to not run on DC.  A lot of people who run DC/DCC capable decoders turn off the DC capability when they run them on DCC systems to prevent full speed runaways that sometimes happen when a decoder doesn't see a DCC signal soon enough after it gets power, so it assumes it is on a DC system, and, because it is really on a DCC system, it sees full track power and sends that to the electric motor.  Without the ability to use a DCC controller to read the appropriate CV in your particular decoder we are going to have a hard time figuring that out.

Have you joined the MRC discussion group on Groups.io?  That is the place that is most likely to be able to give you advice on what your controller is actually doing, and whether they have seen this problem before and know how to fix it.

I am not familiar with your particular locomotive, but, since you are not getting any other replies, I'll take a stab at helping.

I see that your MRC Tech 6 Sound Controller has direction control buttons and assume that you know how to use them.  So, I am going to focus on the locomotive, which I am not familiar with.  I suspect that it has a decoder installed in it to produce sounds, and that it might run on DCC as well as DC.  Please let us know if this is the case.

Also, please tell us what you mean by "only" and "backwards".  To try to be clear, let's say that you place the locomotive on your track with the "front" facing right, and when you turn up the voltage, it runs from right to left, that is, backwards.  When you try to change the direction by pushing the direction buttons on your controller, I am assuming that it still runs right-to-left, even though you tried both buttons.  And, the way I read your post, it seems that if you turn the locomotive around on the track so that it faces the opposite direction, it now runs left to right, that is still "backwards" with respect to what you consider to be the front of the locomotive.  

Is that all correct, or do I misunderstand something about what is happening?

There are also small circular bubble levels, often seen on camera tripods to make the pivot vertical.  Then work well for small scales like N.

Painting structures rather than using the cast plastic color was always my practice, so i can model these buildings in whatever color and level of decay fits my era for the building style.

What always seems "off" to me about model railroad buildings it their small depth back from the street.  Real buildings like the DPM models tended to be at least twice as deep as the models, often much more than that.  In particular, the model of the "movie theater" looks like it would need an unusually wide projection lens to fill a screen something near the width of the building, given the depth available in the building, especially if there is a popcorn stand in the lobby.

The DPM modular components can be used to extend these buildings toward the rear.  Or, multiple kits can be kit bashed into one deeper building.  But, either option is costly.

Well, I did get a Lego set to make a steam engine or caboose (depending on how I put the parts together).  t was actually fun while I was away from home for Christmas, but doesn't exactly fit my modeling period, road or scale.  So, I need to make a shelf for it, somewhere.

Been there, gotten those.  Now, I make a "wish list" of items by compiling a set of links to them at convenient on-line shopping sites.  That way, people can easily get things for me that they know I will like.  Of course, I tailor what is on my list to the financial and emotional parameters of who the list goes to.  A relatively inexpensive item like a vehicle or other easily recognized item seems best for a child (usually actually a parent) to give me because the child can understand what it is and why I like it.  Some adults who have the same cluelessness about model railroading, so the same types of items work for them, too.  For adults who are "into" model railroading, I might ask for a kit of a building or even just some detail parts for a locomotive, or maybe even a not-so-expensive electrical device.  But, unfortunately for me, I don't have any "Uncle Warbucks" who can give me that brass steam locomotive and those 6 brass cars that go with it.

I buy on eBay, but don't sell on eBay, so all I can say is that sellers do a lot of complaining about how eBay treats sellers.  Apparently, there are several pitfalls and you need learn how to navigate in order to successfully deal with that small fraction of buyers who are jerks or worse.

Other options for selling off your collection include posting the items on the sections of model railroad forums that have "swap" or "trading post" sections where members sell to other members.

But, however you do it, it is helpful to first watch what items like the ones you want to sell actually sell for on eBay.  I emphasize "actually" because there is a wide range of prices listed for the same item on eBay, and many are unrealistically high, so the items don't sell fast, if at all, at those prices.  There are also sometimes unbelievably low prices on nice items on eBay, and those sell in hours, or even minutes.  So, knowing about what your items will sell for is helpful in setting up starting bids, and maybe "reserves" if you have really rare items in great condition.

But, frankly, when I did what I recommended above to see what I could get for some items I no longer wanted, it just did not look like it was worth my effort to sell them for what I could expect to get.  So, I donated them to my local train club (trains) and some local charities (non-trains).  Both then sell those items, usually at pretty low prices, and use the proceeds to further their causes, whether that is keeping the doors open and trains running at train clubs, or helping the needy by the charities.

Quote from: jward on December 18, 2019, 07:01:48 PM

Quote from: Len on December 18, 2019, 05:24:44 PM


If the output of the power pack is wired to the AC side of a bridge rectifier, and the DC side of the rectifier is wired to the tracks, it doesn't matter what you do with the power pack directions switch. The DC polarity to the track will not change. The output of the rectifier would have go through a DPDT switch wired for direction control.

Exactly. The direction of the train won't change regardless of how you throw the direction switch, AS LONG AS THE TRAIN IS IN THE LOOP. Once it exits the loop, you've already set the proper direction to eliminate a short circuit. This eliminates the need for the second direction switch traditionally needed when wiring the loop for DC. The only direction switch you need is the one built into the controller.

OK, now that he has added the use of the direction switch on the controller, I think I understand what Jeff means, but he is not describing it properly/adequately in his posts.

What I think he means is that you can take the DC (not AC) output of a controller and run it through a bridge rectifier and it won't matter which way the direction control switch is set, because the bridge rectifier will take any (constant or alternating) input polarity and convert it to one specific DC output polarity.  So, for the section of rail that is connected through the rectifier, the train will only go in one direction, no matter which way the direction switch on the power pack is set.

He is suggesting that the isolated sections of the loops be fed from the controller through bridge rectifiers, so that the center section of the layout between the two loops can have its direction of travel reversed by the usual direction control switch on the controller.  That much is true.  It does force trains to travel the loops in only one direction, which may or may not matter to this particular original poster.  And, it also requires human attention and action to throw an electrical switch while the train is in each of the loops, otherwise, there will still be a short circuit when the train exits a loop.

Another element of the scheme Jeff is proposing has to do with the alignment of the turnouts at the entrance/exit of a loop.  If it is set for the "wrong" direction for the direction of travel in that loop, there will be a short circuit when the train enters the part of the loop fed by the rectifier.  One way to handle the turnouts would be to use "spring turnouts" that always point in one direction, held there by a rather weak spring, so that when the train comes back into the turnout with it set against it, the train itself can push the turnout to the other position and the train can pass through it without derailing.  That actually works, so, with 2 bridge rectifiers and 2 modified turnouts, an operator needs to only throw the controller reversing switch twice as a train completes a full trip around the layout.  The need to throw the turnouts is removed, at the expense of limiting the direction of travel to just one way in each loop.

But, that is still not an automatic setup for a train to make a complete trip around the layout without human attention and action.  To turn it into an automatic layout, it would still be necessary to add equipment to sense where the train is and throw the controller direction switch (or a dp/dt switch between the controller and the track) at the 2 necessary times per trip.

So,  Jeff's suggestion to use the bridge rectifiers is really no different for the operator than what I posted to begin with for a DC system that allows the operator to reverse the mainline between the loops (and the turnouts that start the loops) with a dp/dt switch between the controller and that section of track.  It does make it simpler for an operator to know which way to position the dp/dt switch as the train approaches each loop, because it removes the option of the train traveling around the loop in either direction.  And, using spring turnouts removes the operator's need to keep track of which way those turnouts are directing the train into their respective loops.

But, getting this approach to full automatic would require more equipment and some complicated reasoning to set it up, properly.  

To do it with DCC instead of DC is logically much more simple for the beginner layout builder.  That is because there are already available DCC components that are purpose designed to reverse the phase (not "polarity") of the electrically isolated sections of the loops as soon as a short circuit is detected, so fast that it does not affect the train at all.  And, those DCC components can also send a signal to automatically throw a turnout whenever they reverse the phase on a section of track.  So, a train could enter a loop in either direction, and the DCC automatic reverser component would allow the train to go around the loop without stopping due to a short circuit and without derailing at the turnout when it gets back to it.  

A DCC system would also allow 2 or more locomotives to be operated independently on the same (electrical) section of track.  So, for instance, a train could stop on the mainline, and a switch engine could come out of a siding with some cars to add to the train and take some cars from the train back into the siding, before the mainline train moves on down the mainline.  As needed, both engines could be moving at the same time in the same or opposite directions at different speeds to break the train, move the cars, and reassemble the train on the same electrical section of track.  

Quote from: jward on December 17, 2019, 08:51:00 PM
One way to do this on DC is to wire a bridge rectifier between the controller and the track. AC leads go to the controller, Dc to the track. You'll still have to gap both rails at each end of the loop, and you'll only be able to travel in one direction around the loop. But it works like a charm and is as simple to wire as any other method. Make sure your rectifier is rated at least 3 amps.

Frankly, I don't understand how what you posted would work to prevent a short circuit at one end of the loop or the other.  Please explain. 

Keep in mind that a bridge rectifier will put only + on one rail and only - on the other, and that those two opposite polarity rails will be connected with each other at the turnout for the loop.  Yes, you can isolate both sides of the turnout from the rest of the loop, but, at those isolation points, there must be a mismatch in polarity across on set of gaps or the other.  There will be a short circuit when a train bridges the gap with the polarity mismatch.  So, something must reverse polarity between the time that the train crosses the first set of gaps and the time that it reaches the second set of gaps.  The options are to either reverse the section of rail in the loop (typically done for DCC set-ups), or reverse the mainline (and switch) often done with DC analog set-ups).

If you want to make it reverse automatically, then DCC is the easiest (not cheapest) approach, because there are devices already made to do that for you and throw the switches on the splits for your two reversing loops while the train is in a loop.

But, if you want to do it by hand, each time the train enters a loop, then all you need is a simple double-pole/double-throw electrical switch.

The wiring for the simple hand operated layout is different from the DCC layout.  With DCC, sections of each loop get their rail phases switched automatically, while the train is in the loop, by an electronic device that senses a short circuit when the train bridges an insulated track joint where the rails are out-of-phase across the joint.  That happens so fast that the sound on the locomotive does not even notice it.  And, that same electronic device can make the turnout at the end of the loop throw when the phases reverse, so that the train does not derail when it gets to a turnout that is set against it.  So, with a set-up like that, you could just start the train and let it run, unattended, without it stopping or derailing on a layout that is basically a single track that connects 2 reversing loops. 

But, with DC, if you are going to throw the turnout of a reversing loop by hand whenever a train has gone into that loop (so that it can come out without derailing), then it is not much additional work to also throw an electrical switch that reverses the polarity of the rails on the section of track that connects the two loops while the train is completely in a reversing loop.  That is what the dp/dt electric switch is for.  You feed the section between the twp reversing loops through the dp/dt electric switch so that it can be made to match the polarity of one end of a reversing loop or the other end of that loop, instead of switching the polarity of the loops.  That way, your train is not on the section of track while it changes polarity, so even if the locomotive has sound, the slow manual switching process will not affect it.

The rail is not the only thing that expands and contracts with changes in various ambient conditions.  The layout base can also expand and contract at different rates than the rails.  If wood or other fiber materials are use for the layout base, humidity changes may be more significant than temperature changes.

Gaps aren't a bad idea, even in "climate controlled" spaces.  Even in my house, summertime and wintertime humidity changes from something like 45% to 65% at extremes.  And, those extremes do not include what happens when there is a loss of power that kills the A/C or heat for a while.  And, in basements, there is the occasional flood from gutter problems, hot water heater problems, etc., etc.  So, my reasoning is "better safe than sorry."

Also, let's draw an distinction between electrical gaps and expansion gaps.  Electrical gaps are there to prevent short circuits or otherwise isolate track sections electrically.  It is important that those types of gaps do not close due to expansion.  So, typically, it is recommended that they be filled with some sort of insulating material.  A piece of plastic that is glued in-place and then trimmed/filed to match the rail contour is what is usually done.  But, then those electrical gaps cannot close, so they cannot absorb expansion.  So, additional gaps that are not filled with anything are used to accommodate expansion.

Some folks glibly cut electrical isolation gaps and do not fill them, and have neither short circuits nor buckled track.  They are lucky.  Some folks go to great lengths to use non-climate-sensitive layout materials and still cut expansion gaps.  They never seem to have problems with expansion.

There really isn't a rule of thumb for model layouts.  You do what you like, within the limits imposed by your equipment. 

You say you will have a single track oval.  With DCC you couldrun more than one train on the oval at the same time, but will have to make sure one doesn't catch up with the other.  (Obviously, you can't run 2 trains in opposite directions on the same oval, at least not more than half a lap!)

The length of a train will be limited by how much your locomotive can pull.  And, that will vary with different locomotives, and also with the layout - does it have grades? sharp curves?  You will wear locomotives out (especially traction tires) if you load them down so much that the wheels slip a lot on grades and curves.  Of course, you don't have to pull the longest train possible.  On small layouts, it may be more a matter of what looks best to you.

You did not mention switch yards.  Model railroaders have a tendency to have too many cars on a layout for efficient switch yard operations.  But, it is really a matter of what you want to do with your yard.  If it is really just where you store intact trains so that you can easily swap-put which train is running on the oval and which is waiting its turn in the yard, then you can pretty much fill the yard up with trains.  But, if you get into simulating prototype operations where cars come in on one train and get sorted into groups of cars to go out on other trains, then you need to maintain plenty of free room in your yard, or the sorting will become more like trying to solve a Chinese puzzle box.

In the end, you do whatever you want to do on your own layout.  But, you usually need to start doing it to figure out what really appeals to you.

Imagination and "some day" planning can smooth out the wrinkles in this hobby, even if you do really want to follow a prototype.  I enjoy things B&O around the mid-1950s.  But, there is limited equipment available in N scale that fits that motif.  So, I buy or make what I can, and enjoy learning about my chosen prototype in that period.  But, I am not going to wait until I have perfect models of everything before I run trains.  I can get a model of a USRA 2-10-2 steam locomotive, but not a S-1a type 2-10-2 that the B&O used.  So, even though the B&O never had the USRA version of that locomotive, I am willing to run the model of the USRA version pulling a prototypical consist on the prototype's schedule.  Someday, I may (or may never) get the opportunity to make or buy a true S-1a shell for the 2-10-2 mechanism that I already have, or maybe even a whole new model that is accurate to the B&O engine.  But, odds are that I will never get everything I would need to make my whole layout precisely prototypical during my lifetime.  I just don't worry about that.  If somebody wants to tell me that the B&O never really owned a USRA 2-10-2, my response of "Well, if you would like to make an S-1a shell for me, that would be great!" usually ends the conversation on counting rivets.  And, maybe someday, one of those rivet counters with his own 3D printing machine will volunteer to make that shell for me - one can always hope. 

You seem to be new to model railroading, so you probably have not yet heard the word "foobie".  It means a model that may be reasonably representative of some prototype somewhere, but has been painted in schemes for other railroads that might not have ever had that same equipment.  Manufacturers do that to increase sales of the basic locomotives, so that they spread the development and tooling costs over a wider customer base and keep prices down for customers.

Many customers don't care that much about prototype accuracy, so the strategy of marketing "foobies" works.  But, for a customer who does care about prototype accuracy, it pays to do your research homework before you buy, because there are plenty of foobies on the market.

As for asking Bachmann to change the number on a locomotive that you purchased, I would not expect them to do that.  But, you can do that yourself.  Removing numbers and replacing them with decals (or rub-ons) is a skill that most model railroaders who care about prototypical accuracy develop early in their hobby.  I am not going to get into that in this post, but you can probably find several techniques posted on model railroader forums and illustrated in YouTube videos.