Issue with TCS CN-GP decoder installation (N Scale)

AlJo Feb 5, 2014

  1. AlJo

    AlJo TrainBoard Member

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    Hello folks!

    This has to be the most fusturating projects for me. You see, the first installation of CN-GP was done without kapton tape and bad quality of solder wire (I believe its not even a resin core). This cause the decoder to fried up. I sent this one back to TCS for replacement thanks to Goof-Poof warranty that they have.

    Its my first time installing and soldering DCC into locomotive. Obviously lots of lesson learned. First, I bought two new 1/4" kapton tape and a better quality resin core wire (High grade, 60/40, .03, 1 DIA, and 4.0 oz)

    Once I got required materials, I went ahead and get another decoder (I have at least 4 locomotives that needs CN-GP, so its fine that I got 'two at the moment'). I installed everything according to instruction provided by TCS... religiously. Kapton tape included, better soldering work and so on.

    The result was much better finish product. I went ahead and put it on DC track and see if I can test it... It does not run at all. I saw small, tiny, flash but that was it. I couldn't tell where was the flash came from (its like bright silver kind of flash). I went back and double check everything. No wire are touching, the motor is separated from frame thanks to kapton tape, no loose wire touching the frame, and so on etc etc etc etc. But one of the things that Im worry about is orange/grey wire being pinched by the frame. The motor plastic frame though do have a notch for the wires to go through.

    I am at lost. I would love if there's a DEEP instruction regarding to installing DCC (wire) decoder into locomotive. EVEN a basic instruction how to perform solder work. Regardless, what do you guys think is wrong with this decoder/locomotive? When a DC throttle is applied, there is no light therefore there are no pick up. There are no sounds nor motion either. I had one thought that maybe it cant move unless I use DCC application?

    Thank you for any help provided!
     
  2. jhn_plsn

    jhn_plsn TrainBoard Supporter

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    I fear the worst with the silver like flash.

    Can I suggest to remove the pinched wire situation. File or cut a groove or gap so they are not pinched. You state that the motor is isolated form the frame but how about the motor tabs? Is this an Atlas or Kato unit. They are different in that Kato has additional bits of frame that can reach the boards at undesirable locations. If it still won't fire up I would put it on the program track and do a decoder reset.

    I know its not much but hope it helps.
     
  3. AlJo

    AlJo TrainBoard Member

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    What are the worst case if it is a silver like flash? What does silver like flash usually means? Fried decoder? Short? My first decoder was smoked with clear evidence of smoking from the decoder. This one, beside the flash, shows no evidence of whatsoever. Nothing 'smokin'.

    This would be Atlas. Most of my locomotives are Atlas. This case is a GP7, GP9 and GP9TT frame (although all are 1995 year GP style frame). All motor tab/lead/or any other metal touching to frame is nil. None of em are touching or covered in kapton tape.

    I do not have any access to DCC and programming track until my next club meet. :(

    Edit: I have provided all detail pictures (hopefully crisp and clear to spot any issues). For more infomation: Wires are long so I can make sure everything works and not making mistakes. I add small amount of solder to rear end decoder tab so it can grab on to frame.
    IMG_5773.jpg IMG_5774.jpg IMG_5775.jpg IMG_5776.jpg IMG_5777.jpg IMG_5778.jpg
     
    Last edited by a moderator: Feb 6, 2014
  4. Ironrogue

    Ironrogue New Member

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    One thing I try to do before applying power after a decoder install is to use a multimeter set for continuity testing and probing the decoder motor leads (orange/grey) and the frame sides...there should be no continuity. Not that long ago I did an install similar to yours and found that the motor casing was contacting one of the frame halves providing the aforementioned continuity which is a great big NoNo! To solve, I chose to paint the motor case with a couple of coats of nail polish. Most likely not what a pro might do but so far working as expected. Hope this helps and good luck with the next one. Another useful tool is a low power jewelers loupe to look for stray solder and other possible contaminants.
     
  5. traintodd

    traintodd TrainBoard Member

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    I've done about a dozen of these on gp7's and i9's and on gp35's with two fails, 86% I guess is OK as a success rate for them I guess.... The two fails were because the frame cut into a wire and shorted out the board. Just looking at the pics you have provided, I would carve out bigger channels between the frames at the top and carve out channels for the motor wires to the boards. Also, those small ridges on both ends above where the boards slide in to the frames, , carve a pretty good size channel through there as well, that's a real easy place to pinch a wire. I hope you are not leaving all that wire up at the top as well, that's just asking for a wire pinch and a short. Cut the wires to length with just enough to reach between the boards and a little tiny bit of slack, and make sure all the wires fit between the frames with no wire creeping out above them. I even put a piece of tape across the frames to make sure the wires stayed in the channels. I was so paranoid about shorts with these things, I even covered the metal motor frames with electrical tape just to be sure. With this light a gauge of wire and all the sharp edges on these frames, you can't be too careful. I can take some pictures tomorrow of my installations and post them if that would help.
     
  6. AlJo

    AlJo TrainBoard Member

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    Todd,

    That would be great.

    Others, I knew wire pinching is a big deal. I have checked and thoroughly checked. There are no evidence of wire pinching or shear. I might have to consult with TCS support and see what they think. I will go back and triple check regardless.
     
  7. jhn_plsn

    jhn_plsn TrainBoard Supporter

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    Now that you have it apart can you put DC power to the tabs of the decoder to test outside the frame. It looks to me like the grey and orange wires need a larger path through the frame.
    The flash could have been a blink from one of the lights, but when you stated a silver like flash it sounded more serious like a blown decoder. Fingers crossed that is not the case.
     
  8. AlJo

    AlJo TrainBoard Member

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    My gut is telling me that its a blown decoder. My 2nd. :(

    I will wait for couple more days for a response from TCS and see if that confirms too.
     
  9. Adrian Wintle

    Adrian Wintle TrainBoard Member

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    I would suggest that you not do the first test of a DCC install on DC. Do it on a programming track, where any issues should show up without damage to the decoder.

    I've done a bunch of CN-GP installs with no real issues, but it sometimes requires a few tweaks before it is good.

    Adrian
     
  10. traintodd

    traintodd TrainBoard Member

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    Here are a couple of pics, I hope they are helpful. I'm sure some of the purists will object to my liberal use of electrical tape, but it works. Maybe some of the more talented people here can do one of these installs consistently without opening up channels in the frames, but a Dremel with a cutting bit makes it pretty easy for me to be safe.

    I also need to thank you for this thread for another reason. I checked another locomotive, an early install, and somehow, it worked without cutting larger channels in the frame, but a couple of the wires had some pretty good divots in them, so I'm going to pull it apart and re-do the install with larger channels for the wires. It was just dumb luck that one didn't go crispy critter on me. DSC06703.JPG DSC06704.JPG
     
  11. Arctic Train

    Arctic Train TrainBoard Member

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    I feel your pain AlJo. I've blown a few of these picky little decoders myself. I could attribute one of my failures to the solder job on one of the motor leads. The solder hardened with a tiny burr. I didn't think much of it since I was wrapping the leads with tape. When I installed the motor, the burr poked through the tape and contacted the frame. On first try.. ZZZZZZZitt, flash, poof, another one bite the dust.. DOH!!!
    You might want to check that possible short location. Sometimes even tape isn't enough to guarantee isolation. On the happier side, once you get the decoder installed and working I think you'll be impressed with its operation. Very quiet and great slow speed attributes.

    Brian
     
  12. r_i_straw

    r_i_straw Mostly N Scale Staff Member

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    Up until a few years ago, I did decoder installations for one of the local train stores in Houston. Over the years I must have installed close to 1000 decoders. Of that, there have been a few instances where a properly installed decoder has self destructed after being installed or when on my decoder tester where I program them and check them out before installing them. It is rare but it does happen. And I have seen it in more than one brand.
     
  13. nscalestation

    nscalestation TrainBoard Supporter

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    From the photos you posted it looks like you are working with the Atlas GP7 / GP9 mechanism. I have done lots of these and have a few of suggestions to smooth your installation process.


    1. File down the sharp edges on the top of the frame on the front and rear.
    2. File a little round notch on the top for motor wires to come out.
    3. Cut a notch on the top of the motor saddle for motor wires to come out.
    4. Remove motor wires from decoder board first and wire up the motor and re-assemble the mechanism. Then you can test run the motor on DC, check each wire for any shorts to frame, etc. before installing the decoder.

    I have a post on my DCC blog that shows these steps more clearly than I can explain them. I’m just about to do 8 more of these myself.

    http://www.n-scale-dcc.blogspot.com/search/label/Loco: Atlas GP7 or GP9


    Brad Myers
    Peninsula Ntrak / AsiaNrail

    My Blogs:
    http://www.n-scale-dcc.blogspot.com/
    http://www.palisadecanyonrr.blogspot.com/
    http://tokyo-in-nscale.blogspot.com/
     
  14. hoyden

    hoyden TrainBoard Supporter

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    Brad,

    Thank you for sharing your installation technique. I've installed a few of these decoders without doing any of the frame modifications but I can see that doing them would have made the job much easier with more assurance of not shorting something out. I have a few more installations in my future so I will have ample opportunity to try out your suggestions. I've learned to check the installation with an ohmmeter to verify the motor isn't shorted to the frame, and I try out the decoder on the programming track before putting the real juice to it.
     
  15. AlJo

    AlJo TrainBoard Member

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    Thank you guys for more helpful insights! Most thanks goes to Brad for more tips and advice.

    TCS confirmed that its a blown decoder. It is now already shipped out to TCS. I will not get any more CN-GP decoder until I get those two installed properly. More on to that later!
     

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