It's not though. Athearn Blue Box locos, the ones that have the clip across the top, have the chassis grounded to the rail, should be the fireman's(left) side assuming the short hood is the front.
The older ones with the metal sideframes are slightly different as far as the truck but the clip and chassis stuff is pretty much the same. Eveythign I can think of that could short out in this area would NOT blow out the decoder, it would just cause a short and shut down the track power. Other things that can happen are that the centers of the gears can be cracked out and the wheel stubs pushed in so far the make back to back contact, but again this is just a dead short across the track, not the decoder.
Can you get some pictures of what you've done? There must be something that is being overlooked.
--Randy
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From what you are describing, my Athearn is wired up like the protos. After frying the first board, I was looking for a short and found that the wheel could potentially make contact with the metal coupler covers and that created a huge spark (that...I'm shorting out kind of spark). so I fixed that by applying insilating paint to the bottom of the frame, but still another board fried after a few passes on the track. Now, I have found a possable solution.....Nail polish. It is non-conductive, thick, and resistant to scratching. I will let you guys know if it works.
TO tell the truth, more often than not when connecting the decoder up so that the orange wire goes to the motor terminal that used to be conencted to the red wire, and grey to the black - they run reverse. Since NMRA DC standard is forward when right rail is positive, and they run fine in DC (well, except my Proto Geeps - Proto wired them to run short hood forward, not correct for my particular railroad - so not only do I have to reverse them I have to take the crew out and try to flip them to face the other way) I can only assume this discrepency is caused by the way the multipe diode boards are used in DC to make the contast brightness directional lights. It's really no big deal since you can easily flip the direction with CV29 - so I prefer to keep teh color code constant where applicable. SOme older locos have all black wires inside, no color code. So the side of the motor that was connected to the right rail is where I connect orange, the left rail gets the grey - left and right referenced as if sitting in the cab facing the forward direction.
A note on another post - the Proto ALco switchers are NOT DCC ready - the orange wire, bottom of the motor, is connected to the frame. The trucks are isolated from the frame, so under ordinary circumstances there is no issue. However, there is enough movement int he trucs that if the loco derails, the wheel could contact both the rail AND the frame - poof goes the decoder because the track side gets connected to the motor side. To make those totally save you need to sodler a new orange wire to the lower brush cab, clip off the looped tab that is there, and put some tape under the motor. The end cab of the motor that holds the brush holders is plastic, so it does not matter than metal screws hold the motor to the chassis, that's not part of the circuit.
Which brings up the two basic designs: in Athearn locos, the chassis is connected to the rails, The bottom of the motor touches the chassis for one side of the power pickup. For those you must isolate the motor fromt eh chassis. Other locos are like the Proto switchers, the chassis is connected to the bottom side of the motor, but insulated from the rails. These types of locos are basically safe except in the case where a wheel could be pressed into contact witht he frame while still on the track. Bottom line, if either the orange or grey wire comes into conact with the red or black, directly or through metal like the chassis of the loco, the decoder is toast. You cannot apply power to the orange and grey - do not even ever attempt to test if the motor is working by applying DC power to the motor terminals if a decoder is installed, this will also damage the decoder.
To further clarify (and not jack up my post count):
The problem I had was the loco running backwards and not frying the decoder. My novice ability was due to the "DCC ready". This loco had an 8-pin plug, all I had to do was pull out the existing DC board and plug in the 8-pin decoder. I had no clue what the colors were for. Now that I am hard wiring decoders, I know what each color is for and where it's supposed to go. You could use purple polka dot wires as long as they go from the correct "point A" to the correct "point B".
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KevinsHope Hmmm...well...you definitely sound like you know what your talking about. Let me ask this. I was having this issue where the loco runs the opposite direction on a DCC track as it does on a DC track. For example, if it goes forward on a DC track (wired for anolog), then it will travel in reverse on DCC. Lights also respond oposite of how they should be responding. Someone said this means that I have the motor leads reversed. If this is the case, and I am still wiring orange and gray to the top and bottom respectively (which may be reversed), and the red and black wires to the positive and negative respectively, could this cause a dcc unit to fry? May sound like a stupid question, but I'm just trying to cover all my bases.
Hmmm...well...you definitely sound like you know what your talking about. Let me ask this. I was having this issue where the loco runs the opposite direction on a DCC track as it does on a DC track. For example, if it goes forward on a DC track (wired for anolog), then it will travel in reverse on DCC. Lights also respond oposite of how they should be responding. Someone said this means that I have the motor leads reversed. If this is the case, and I am still wiring orange and gray to the top and bottom respectively (which may be reversed), and the red and black wires to the positive and negative respectively, could this cause a dcc unit to fry? May sound like a stupid question, but I'm just trying to cover all my bases.
I had this problem with my HO scale Proto 2000 S3 switcher. The loco was "DCC Ready" and when I finally installed a motor function decoder (no sound), it did what you describe - ran backwards in relation to the control center commands. Not knowing much about DCC and how motors are wired and for what, I simply changed the controller to match the loco.
Since I have begun to convert my locos to sound: I have compared decoder installation instructions from several manufacturers and read most of the posts on here, I have realized that the left and right rail pickups on the S3 are backwards. Red is supposed to be the right rail pickup and black is the left rail pickup; however, on my loco, the red wire goes to the left rail and black wire goes to the right rail. Now I know why it ran backwards after installing the decoder - it was wired wrong from the factory and I didn't know enough about DCC to realize it. I simply followed the instructions "red decoder wire to red wire on motor and black to black", etc. When I install sound, I will correct this.
To answer your question, this wiring snafu should not cause your decoder to fry. Something else is sending to much juice to your decoder.
Yes, Randy knows DCC. I put my trust and faith in him with the guidance he gave me when I first started installing decoders.....and they work, the first time!
NO it would not cause the decoder to fry. Randy, who DOES know what he is talking about has already responded to the issue of the reversed motor connections in the OTHER thread. The problem with dual threads on the same subject, and essentially asking the same questions is that you are getting the correct answers but they are not together.
In summary......
1. If the decoder goes POOF instantly when you apply power to the track, it is installed incorrectly and there is a dead short in the wiring. Either the motor is not correctly isolated or one of the function outputs is burning our because of current flow. Either way it is an installation issue that should be easy to find with a multimeter.
2. If everything works, but in the wrong direction you have the motor wires flipped. Again, it does not really matter the why of this. The fix is to flip the wires or reverse the operation of the loco and the lighting with CV adjustment. Trivial to do and done all the time. I think at one point in one of the threads it came out that you have actually swapped out the motor on this loco, well it is very possible you put the motor in backwards, this would cause reverse direction. No big deal, fix it with CV reversal. This issue has nothing to do with decoders going POOF.
3. If the locomotive runs but the decoder only goes POOF as a result of frame touching something else, such as a side frame, then it points to an installation problem, but as you already discovered you can fix the problem by isolating the frame and eliminating if from the current path, You just need a more permanent solution to this for which you have suggestions.
4. If the locomotive runs but the decoder goes POOF when the loco is under strain or stalled then the current draw of the motor is too great for the decoder. If you have installed a new motor then this is unlikely to be the problem.
The internal conduction path for current flow from the rail pickups to the motor in a DC loco is really quite basic. It can be mapped out quite simply with the basic meter recommended several times. That same meter can be used to verify the presence or absence of shorts, many examples of how to do this have been given. Like others that have contributed, I have performed many hard wire installs on older locomotives. The use of the meter is an invaluable aid and can eliminate the issues that you are having. I think that it may be time to put your locomotive into the hands of an experienced decoder installer and look over their shoulder as they do the installation.
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Having read most of both threads If I were you I would gladly pay someone to fix the logo for me. Or just give up and throw money at it.
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Since a proper install in an Athearn loco isolates the motor brushes from the frame, a sideframe touching the frame would cause only a track short (possibly), not a short that would hurt the decoder. There is still some point where one of the motor wires is touchign the frame or the rail pickup - this is the only thing that will cause a catastrophic failure of the decoder. Even the problem of a function wire I mentioned int he other thread would more than likely fry only the function outputs - the motor would still respond but no lights would work.
The motor may be new but if it's touching the frame you will get a short.
To isolate the motor take a piece of electrical tape and put it between the motor and frame so that no part of the motor touches.
Springfield PA
Yeah....that's the right post. Sorry I didn't provide a link. I think I might take the advice above and just buy a newer model. I know about the brush clip and I am sure I had it isolated from the frame when I was running this loco with DCC. The reason for the short still illudes me to be honest, but it has to be the frame/ truck contact because I've ruled out everything else. The motor is a new motor. It is not a short. What else could it be?
woodone Sure wish you would have linked us to your earlier post. Would have made looking at it much eisier. As it is now I am not sure that I am looking at the correct post.
Sure wish you would have linked us to your earlier post. Would have made looking at it much eisier.
As it is now I am not sure that I am looking at the correct post.
I believe that this is a link to his other post:
http://cs.trains.com/TRCCS/forums/t/188874.aspx
On the Blue Box locomotives the frame is a conductor for one of the rail pickups. I belive it is the right rail. At any rate I can't see that a wheel touching the frame is causing the decoder to go bad.
Are you sure that you have the motor insulated from the frame on the bottom side of the motor?
The spring clip that holds the brush in the motor also makes contact with the frame. There is a small tab of the clip that is made like a spring and pushes to the frame. Flaten this piece of spring to the clip via soldering (you want to make it flat) then put some Kapton tap on the clip and also to the frame where the clip used to touch the frame. Also make sure you have the wheel sets in correct,
Just curious, but don't you think you'd be able to save yourself a lot of grief by just buying a newer Athearn SD45 and swapping out the chassis? The newer RTR ones have the quick-plug, so you wouldn't even have to hard-wire it. But it would seem that even an old blue-box SD45 would be an improvement from where you are now...
If the paint worked, but temporarily then you have the solution, you just need a more permament fix. An excellent insulating tape like Kapton tape could well be a solution. I have vague memories of seeing an article where some thin styrene was used to isolate the trucks from the frame.
You have to be careful as something too thick will lift the frame and potentially mess up coupler alignment. If I recall correctly the article using the styrene insert actually ground the frame so it would not alter the height.
Hello all,
I have posted once before on this forum about my SD45 athearn. See that first post if you need details. I've fried a few DCC chips trying to upgrade it from it's old DC roots to the newer DCC system. Through the time honored and laborious process of elimination, I've concluded that the only thing that could be causing the problems I'm having must be related to the metal truck frames on the trucks. They occassionally brush against the frame of the loco, which is metal, and cause a short in the system. I can't replace the truck frames with plastic ones due to the way they are made. The trucks are sorta rivited to the gear housing, rather than screwed. So....Any thoughts on how I can either bypass the frame all togeather or isolate the trucks from the frame in some way that will keep them from touching. I tried using acrylic paint on the bottom of the fram, which does prevent circuit flow, but it rubbed right off within a few trips around the track.