TCS install question on CN-GP

drgwspup Dec 24, 2021

  1. drgwspup

    drgwspup TrainBoard Member

    Hi everyone, Hope everyone is having a great holiday season so far.

    Posting here since the TCS decoder in question is exclusive to N scale. Mods, please feel free to move it if I am in error.

    I am confounded. Installed TCS CN-GP in Atlas GP7. Prior to tightening up the wires did a test run. All was good and it ran well. Tightened up the wires and put some kapton tape to hold them in place. Had to adjust the lighting and direction of travel CVs. Started having issues so re-set the decoder.

    Now runs well in one direction and light functions properly (Basic on/off). But when I change direction, motor won't turn over and the light changes from constant brightness to Mars effect when I increase the throttle? but the CV is not set to the Mars application. Is this some kind of built-in warning in the decoder?

    The fact that it runs great in one direction and not the other is a mystery to me. So I'm asking the TB collective to grant my xmas wish and tell me what I did wrong.

    Merry Christmas everyone!

  2. tehachapifan

    tehachapifan TrainBoard Member

    It's been a LONG time since I worked with one of those but, IIRC, the flashing headlights thing is indeed an indicator that something is wrong. I want to say that it has to do with a speed step mismatch of some type, but I can't recall for certain. Plus, if it is a speed step mismatch indication, I don't know why it would only occur in one direction.

    One thing about these decoders is that ALL the frame contacts in both boards need to be making solid electrical contact.
  3. drgwspup

    drgwspup TrainBoard Member

    Well, when you have old locos and are late to the DCC party, CN decoders are a necessity.

    Thanks for your thoughts, I appreciate your rely given the pre-holiday request. Hope you have a very Merry Christmas.

  4. Sumner

    Sumner TrainBoard Member

    When it ran well was the shell off? I'd try and get back to where it ran OK before messing with the wires and adding the Kapton tape. Then move forward one thing at a time looking for what might be causing the problem.

    Being cheap I've put some less expensive decoders in loco's I could of used CN decoders. The CN's still aren't 'drop-in' by any means and only save you from connecting the two track power wires. All the rest still need to be connected as you would with any hard-wired decoder install. Another advantage is that it might save you some frame milling for clearance. I hate using the word 'milling' as I thing right away that turns some people off since they don't own a mill. I have one but hardly ever use it as a saw and a Dremel like tool take care of the 'milling' just fine.

    Here is an example of an alternate decoder approach than the CN one ...

    Nothing wrong with going the CN route but there are alternatives that are almost as easy and less expensive if you have a lot of loco's to convert.

  5. Thomas Davis

    Thomas Davis TrainBoard Member

    I've done several CN-GP and CN installs, and they all had problems of some sort, but all eventually worked. Most of my issues related to programming (the TCS seem to much prefer 13 volts to 12 on the programming track, and I have found myself giving it the same instruction 2 or 3 times before it "takes") and soldering. So my advice would be to first check that all the solder connections. In one of my installs, I had one single strand of wire (essentially invisible to me as my eyesight isn't what it used to be) that escaped the pool of solder and touched the one adjacent- I'm probably lucky it didn't smoke the decoder). Anyway, I fixed that and that decoder worked fine after. Also worthwhile to check the connections of the gray and orange motor leads to insure they are contacting properly, and that nothing is getting pinched in the frame or otherwise shorting.

    Also worthwhile to check the CVs one by one to be sure things are as they should be.

    But if basic diagnostics and double checking don't work, by all means contact TCS customer service. I've had excellent responses from them where they walked me through installation issues, and in at least one case, based on "symptoms" I described, were able to diagnose a fault in the decoder, that they asked me to return to them, and they replaced it under warranty.

  6. drgwspup

    drgwspup TrainBoard Member

    Thanks everyone for your comments. I've double checked everything and don't see what the issue is. I was hoping that this was an issue seen before. I'll contact TCS tech support.

    Have a Happy New Year

    Sumner likes this.

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