N scale Kato/Atlas U25B starts and stops then does not run and CV8 value reads NoPg

a fan of chessie Sep 13, 2020

  1. a fan of chessie

    a fan of chessie TrainBoard Member

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    I have a N scale Atlas/Kato U25B-IIb which has idle for 3 months on My large Yard and today I wanted to run the locomotive and was less than successful. The locomotive would run forward then stall then run forward again and then stall. This same process happen when I ran the locomotive in the reverse direction. I could hear the motor buzzing when it sat on the track. The Locomotive has TCS CN-GP hardwired in. I use the digitrax DCC system (5A Super Chief with DCS100 command station with a DT400 throttle).
    So I placed the locomotive on the programming track and the command station beeped 4 times. I then went into programming mode on the the throttle to read the CV values to set what is happening. The First CV value I read was the CV8. The display should have read CV8=153 for TCS decoder, But instead it displayed CV8=NoPG. So I left the locomotive on the programming track and switched off the programming track and successfully operated other locomotives that have sat on the yards tracks for the same amount of time. As frustrated as I am I decided to shut down the DCC system and walk away for a few hours.
    I came about 2 hours later powered up the the DCC system . The N scale Atlas/Kato U25B-IIb locomotive I left on the programming track was moved over to Yard track and the programming track shut down, entered the 4 digit address of the locomotive into the Digitrax DT400 throttle and the locomotive ran in the forward direction and the reverse direction 3 times each then just shut down. Therefore I moved the Locomotive to the programing track, switched on power to the programming track and immediately the DCS 100 Command station beep four times. I went to programming mode on the throttle to read the CV values. I tried to read the CV8 value again and received the display answer CV8=NoPg. Therfore I shut the system down and removed the locomotive to My work bench.
    I am frustrated at this point, Therefore I turned to Digitrax support page to search for an answer, but that was futile! So I am turning to members of TrainBoard for Help!!
    I would greatly appreciate any Help. Thank You.
     
  2. Sumner

    Sumner TrainBoard Member

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    I'd start with the basics. I'd probably pull the shell and when the motor stalls check to see if I had voltage on the frame half's where the CN decoder gets its power from. You could also check contact some with the loco off the track and see if you have good connectivity between each truck on one side and the frame half on that side and the same for the other side. I'd want to check voltage when it has actually stalled though as it might be intermittent if you are having a contact issue.

    If you have current going to the CN decoder then I'd try to next check for current to the motor. Might be hard to get to the motor caps to do that though. If there is no current to the motor then I'd suspect the decoder. If contacts are flaky then it probably isn't going to read or write on the program track.

    From your description though it sounds like something is heating up and then not working.

    Let us know what it was and hopefully someone else has a good answer for you,

    Sumner
     
  3. S t e f a n

    S t e f a n TrainBoard Member

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  4. OlyPen

    OlyPen TrainBoard Member

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    Could be an internal, intermittent short in the decoder.

    Have you attempted resetting the decoder? I forget at the moment which CV and value TCS uses for reset. But sometimes that's all that's needed. Otherwise, I'd wager you have a bad decoder.
     
  5. SteamDonkey74

    SteamDonkey74 TrainBoard Supporter

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    If you do all the checks outlined above in Sumner's post, and all of that looks fine, you may be able to reset the decoder to factory settings on your programming track.

    Put it on the programming track and write 2 to CV8. It of course won't stay as 2 if you read it back, but if things are working it should reset the decoder to factory settings. https://tcsdcc.com/sites/default/files/CN-GP.pdf
     
  6. a fan of chessie

    a fan of chessie TrainBoard Member

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    First off Thank You All for Help

    What I did was to take some Summers advice and dissemble the locomotive frame, remove the decoder from the mounting tabs, remove all the existing kapton tape from locomotive frame and motor tabs. Then I proceeded to clean up the locomotive frame of oil and grease. Mounted New Kapton tape on the frame in the locations of where the decoder wires came up from the locomotive, placed kapton tape on the top and sides of the frame where the decoder wires ran between the two decoder tabs and finally placed kapton tape on the motor tabs as well along side of the motor to keep the motor wires from moving. Then proceeded to re-assemble the locomotive and re-installed the decoder.

    I placed the locomotive on the programming track was able to reset the decoder to factory settings. The decoder accepted the factory reset, therefore I operated the locomotive with the factory address of 3 on the yard track with no problems. So I returned the locomotive to programming track and programmed into the locomotive the four digit address (locomotive number). From there the locomotive operates fine on the railroad.

    From now on I will make sure the locomotive frame halfs are insulated properly with kapton tape.
     
  7. SteamDonkey74

    SteamDonkey74 TrainBoard Supporter

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    Excellent! Glad to hear of a positive resolution!
     
  8. OlyPen

    OlyPen TrainBoard Member

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    Good to hear!
     

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