Thank you...and by the way, thank you Yampa Bob for your thoughts about making sure that the wheel trucks not only swivel freely, but that they must also allow the cars to rock a little bit.  I am going to check that as well before I do anything else.  Most of the cars that are encountering this problem are Roundhouse 50' or Athearn 50' boxcars kits that I assembled.  I only had this issue with 1 or 2 of the Athearn 50' RTR boxcars.  I hardly have this problem at all with the 40' boxcars, regardless of brand or whether they were RTR or kits.  No problems with either tank cars or flat cars.  It has happened with the 34' and 40' hoppers, but usually it is only 1 or 2 in the middle of maybe 5 or 6 cars being pulled.   Maybe I did tighten the screw a little too much on some of them, but every so often, I also have this problem with a couple of Athearn and Atlas engines (GP-38 or SD-45).  In the case of the engines that derail, it's usually the second engine in a train that is being drawn by two engines.

I also have a bag of 100 or so Atlas 33" metal wheels.  If the problems continue, I'll try those on the cars in question as well.

Regarding the weights, the weights that I am using are the standard Athearn weights that either come with the Athearn cars or fit the Roundhouse cars.  I also have strips of 1/4 oz. and 1/2 oz weights as well that I can stick to either end of the floors of the boxcars to increase the weight if that proves to be necessary. 

I am going to try all of the above before I try to start fooling around with the frog.  This doesn't happen on all of the turnouts...it only happens on 2 in particular (out of 5).  The cars do definitely rise as they pass over it, though.  I took a photo of a string of 34' hoppers as they passed over it and you can clearly see the tilt as they pass.

As usual, you guys make excellent suggestions that have solved several of my problems in the past, so I am hopeful that your suggestions about resolving this issue will prove to be equally fruitful.  I hope that this discussion thread will be of help to others.  Thanks again.

Where can I get a wheel gauge?

The 33" metal wheel sets that I have been using are made by Model Power.  However, RTR cars made by Atlas with metal wheels were also derailing...especially cabooses....and it is right when they hit the frog.

The Athearn RTR freight cars with metal wheels didn't derail...except for a caboose or two.

I read the NMRA reference and was totally confused.  I just didn't understand the terms that they were using.

Thanks for your advice though.  I am not sure how I am going to deal with this.  Jestor's comment was very helpful when he noted that if it is a problem with a certain turnout and not all of them, then I have already ruled out the wheel gauge.  It's not all of the turnouts where this happens.  For someone who doesn't know exactly what he is doing, I am reasonably sure that it is not the wheel gauge.  The Model Power wheelsets seemed to be of very good quality.

If anyone else has any other thoughts...especially about shimming the frog and how best to do that, please offer your two cents...you comments and suggestions are most welcome.

Has anyone had a problem where either engines or cars (especially longer cars such as 50' boxcars) derail when they pass over a Bachmann E-Z Track switch/turnout?  What can be done about this?  I have this problem intermittently whenever a train crosses a #5 or #6 switch/turnout.  It only seems to happen with certain switches/turnouts.

I looked closely at the switch/turnout(s) in question and noticed that, as the cars cross the second rail of the track that turns out, there is a grooved plate (made of either plastic or soft metal) that appears to raise the wheels of the cars as they cross it.  Can or should that groove for the wheels be deepened or am I on the wrong track here? 

What I am talking about here is where the switch/turnout is closed so that the cars are going straight down the track.  It seems like the wheels  of some cars want to go with the turnout (as if the switch was open) instead and it makes the car derail.  This also happens with some the longer engines like the Athearn SD-45, especially if I am running a 2 engine train.

Your thoughts would be helpful.  This appears to be the only problem with my track layout.  Otherwise, the trains and cars run fine.

I had once asked if it was appropriate to ask questions about other products and was assured that was OK to do so in the General Discussion forum.  For example, I asked about how to make DC to DCC conversions of Athearn engines and a very informative discussion ensured.  I also asked certain questions about certain Atlas engines.

Is this sort of thing still permissible...or are we limited to discussing Bachmann products only?  I will, of course, abide by the Code of Conduct but that's still not clear to me.

I just wanted to drop a note to everyone say hello and to let you know that I have sucessfully converted 8 Athearn F-7s , 1 Athearn GP-38, 1 Athearn GP-40 and 2 Athearn SDP-40-2 engines from DC to DCC.  I used the Digitrax DH 163AT DCC decoders.

Your excellent advice and guidance made this possible and I saved a lot of money by doing it myself.

I hope that our on-line discussions were as much help to others as they were to me.  It wasn't hard at all.  Thank you! 

Thanks guys.  As usual, you have answered my questions.

I have never shopped Roundhouse products before and I am looking at some freight cars (in particular 50' boxcar kits [maybe a couple of 40' boxcars] and maybe a caboose or two).  Are they made of plastic or metal?  I tried to find out some information about them on the internet and couldn't find out much of anything except for the fact that the company that bought Roundhouse also bought Athearn.  Are they of comparable quality to Athearn?  Atlas?  Walthers?  Bachmann?  Should I avoid them? 

I am just looking for some advice here.  My engines are Atlas, Athearn and Bachmann.  My rolling stock (freight) is Athearn, Branchline, Walthers or Atlas.

Thank you for your response.

OK, I think that I have the mechanics of the decoder installation down.  My last question is what is the best way to secure the decoder and wires?  Thus far, I have been taping the decoder and wires to the top of the locomotive shell.  Is there a better way...one that would secure the decoder and wires to the top of the motor and frame instead of the locomotive?  That way, I could remove the shell without worrying about dislodging any of the connections.

Any suggestions?

I have successfully installed a second Digitrax DH 163AT decoder in another RTR Athearn F-7...and it runs after being successfully programmed.  I will be installing several more over the next couple of weeks.  The two decoders that went up in smoke were definitely blown.  Chalk it up to my learning curve.

Thanks again everybody!

AT LAST...SUCCESS!!!

The solution was something very simple like I thought it might be.  Once I started thinking through how the electrical current flowed through the decoder, I realized that I had not removed the long bar that goes on top of the motor clip and connects to the trucks (the result was that the current  doesn't go through the decoder).  Because I had put it back on after I had replaced the DH163AT motor clips (with the gray and orange wires), it was running the current directly from the trucks to the motor without going through the decoder, PLUS it was making contact with the motor clip that was connected to the orange wire.   Hence the short circuit.

The solution was just to remove the long bar that goes on top of the motor clip and connects to the trucks.  In future installations, you just don't replace the long bar after you install the motor clips with the gray and orange wires attached that come with the DH163AT decoder.

I know how to convert Athearns to DCC and I can do these on my own now.  Once you finally do one of these successfully, it's not that hard.  It cost me a couple of decoders to learn this lesson (I'll re-try them to make sure that they are blown), but even if I lost those rwo decoders, it was still worth the $45.00 for the two of them.  That would be less than the cost of a single DCC conversion by a hobby shop.

I hope that the discussion on this thread will be of help to someone else.  It was a great help to me.

Once again, thank you everyone...and have a Happy New Year!

You know, the more that I think about this, the more that I think that I maybe I shouldn't have reinstalled the long clip.  After all, the plugs on the red wires run from the truck posts through the decoder...but the long clip makes contact directly from the top motor clip (with the orange wire) to both truck posts without going through the decoder.

Does anyone have any thoughts about this?  Could the solution to the problem be this simple?  In other words, the motor is properly isolated...it's not the gray wire making contact with the frame...it's the ORANGE wire connected to the top motor clip which is making contact with the truck posts via the reinstalled long clip.

And yes, I did see the transformer's short circuit signal come on...

The engines that I have tried this on run fine...they are Athearn RTRs straight out of the box and run fine on DC.  I think that the problem may be somewhere in the process you describe as step 3...the red, black, orange and grey wires.

I have been trying to think this through logically and my thinking is that the problem is somewhere in the middle of what I am fixing to describe:  When it comes to isolating the motor, do I need to do anything more than just cover the shiny strip under the motor with a couple of layers of electrical tape...I think that the engine itself still makes contact with the metal frame when I re-seat it.

Question:  Now this is the one thing that I didn't check...should the bottom clip (with the gray wire attached) make any contact with the frame itself?  I am reasonably sure that it still does because I only covered the shiny part on the bottom of the frame under the motor (the rectangular area where the copper is that is touched by the motor contacts) with electrical tape.  Should I make sure that the entire length of the bottom clip does not make any contact with the frame?  The reason that I ask this is because the black wire is connected to the frame via screw and solder and the red wire that plugs into the truck leads would logically make contact with the frame via the current going through the light bulb that makes contact with the frame.  That could mean that the gray, black and red wires are all touching the frame.  I am just thinking out loud here because I am sure that it is something simple that I am missing.  Is the motor properly isolated if the clip and grey wire are still touching the frame? 

The light bulb is coming on when I put the engine on the track.  That means that current is coming from the track through the truck leads and along the long clip to the light bulb and should logically be going to the motor as well through the motor clips with the gray and orange wires...am I correct that the long clip that came with the engine and goes on top of the top motor clip to make contact with the trucks is supposed to be re-installed?  The more that I think about this, the more I have some doubts about re-installing that long clip...

I am sorry to say that things have not worked out.  I followed all of the steps that you said:

1.  I took the engine out and covered the shiny part under the motor with 2 layers of electrical tape;

2.  I removed the old clips (and didn't lose the springs) and attached the clips on the decoder harness (clip with grey wire on botton and clip with orange wire on top);

3.  I attached the red wire to the front and rear truck posts (plug-ins)

4.  I drilled a hole in the side frame, put in a screw and I soldered the black wire to it and tightened it to the frame with the screw.

5.  Attached decoder.  Two decoders have already gone up in smoke. 

After all that, I tried a second engine...and a 3rd decoder.  The headlight comes on and then goes out during the programming sequence...and then comes back on after the sequence is completed.  Nothing else happens.  The engine doesn't move.  This is the second of 2 brand new Athearn RTR F-7s.

Athearns are a major pain (you know where) and I am on the verge of giving up.  Is there a short somewhere?  Why am I thinking that it has to do with the headlight?  Somehing is getting juice or the headlight wouldn't be coming on.  What am I doing wrong?

I need some more help.  This is getting extremely frustrating.

I did not attach any of the other wires to anything.

Finally, if I can't do it, where can I get this done professionally?  I live in the Los Angeles, California area.

Thank you both.  You have completely answered my questions.