Helper Service- The Lights are On But... (TCS CN-GP Decoder)

umtrr-author May 10, 2021

  1. umtrr-author

    umtrr-author TrainBoard Member

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    What, an actual question and not an "eBay Humor" item?

    Yes! And Help!

    This is the situation: I had a friend install a TCS CN-GP decoder in a custom decorated Atlas GP-7 (it's for my home railroad, but that's not terribly important).

    After a long time in storage, I have been testing my DCC-equipped locos. This one wouldn't... mostly. I have an NCE Power Cab.

    I can poll the decoder, I can do and have done a complete reset (a nice newer feature on the Power Cab) and as that is happening I can see the motor turning its little bit each time as happens when you're programming CVs and such.

    The lighting (LEDs) work as expected, forward or reverse.

    However... when applying power, all the way from 0 to 28, the lights come on and "strobe" but the motor barely turns, if at all.

    I have used a bit of Labelle 108 oil, which has helped with some of the other locos that were in storage... but nothing.

    I've also cleaned the wheels thoroughly, to take that off the table.

    I can eliminate the variable that the issue is with the trucks, since I pulled them off, set the loco directly on the track and tried powering it again, which does work... except with the same result.

    I also set the decoder to dual mode, tried straight DC (an MRC Tech II powerpack) and have basically the same result: the lights "flash" and the motor turns a very small amount at a time, not enough to move the loco but enough to show that it is getting some power.

    I'm thinking the next step is probably to disassemble the entire locomotive as best as I can without undoing the solder connections to the CN-GP, which is not my idea of a good time. And probably the next step after that is to replace the decoder.

    So before I do that... any other ideas?
     
  2. ntex

    ntex TrainBoard Supporter

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    I have a couple of locos that I have installed TCS CN decoders in. I would check to make sure both boards are firmly in the frame contacts. I have had to add either a drop of solder to the frame contact pad on the boards or very gently squeeze the frame to the decoder to make it snug. Just a thought.
     
  3. Chops

    Chops TrainBoard Member

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    The thrill of victory, the agony of defeat, the endless issues with DCC.
     
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  4. JBrown

    JBrown TrainBoard Member

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    After a long storage, I have had to clean the motors with a safe contact cleaner to get them to run...
     
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  5. Inkaneer

    Inkaneer TrainBoard Member

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    +1
     
  6. Rich_S

    Rich_S TrainBoard Member

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    A question, as you're increasing speed steps the headlights are flashing on and off? This to me sounds like a short? Is the motor completely isolated from the frame? I've installed a few TCS CN and CN-GP decoders in various Atlas and Walthers / Life-Like locomotives. The one thing I made sure was to place a piece of Kapton Tape over the motor brush leads to isolate them from the frame.

    Motor Connections.jpg

    If the motor is completely isolated from the frame then you unfortunately may have a defective decoder?
     
  7. BarstowRick

    BarstowRick TrainBoard Supporter

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    My thoughts exactly.
     
  8. umtrr-author

    umtrr-author TrainBoard Member

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    Rich, I didn't do the decoder install so I can't be sure about the Kapton Tape placement, but that is something to check. The lights do flash on and off in both DC and DCC modes so maybe it is a short. Is it accurate to say that the decoder can still be programmed in that situation?
     
  9. NDave

    NDave TrainBoard Member

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    Check and make sure your decoder and DCC controller are both set to the same number of speed steps (either both 28 steps or both 128 steps)...

    IIRC, when the decoder in 28 step mode and the controller is in 128 step mode, the lights will flash on/off at alternate steps.

    Is the decoder old enough that it only runs in 28 speed steps? Try setting your controller to 28-step mode...
     
    Last edited: May 10, 2021
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  10. sd90ns

    sd90ns TrainBoard Member

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    Is there good contact between the little tangs on the motor and the tiny pads on the PC board?

    I don't run DCC but I have encountered what I call "DCC Disease" wherein those tangs are not making good contact with the PC board.
    With DCC ready locomotives, or those modified for DCC operation, the motor must be electrically isolated from the frame so that it receives its current from the PC board not directly from the frame.

    The contacts on said PC board can oxidize over time as can the tangs on the motor, resulting in poor current transfer. Those tangs can also get bent such that they are barely making contact with the pads on the PC board.

    The result, the lights come on but the motor doesn't run.
     
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  11. MK

    MK TrainBoard Member

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  12. nickelplate759

    nickelplate759 TrainBoard Member

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    Both boards of the CN-GP must make good contact to the frame on both sides, otherwise weirdness happens. I'd check that first.
     
  13. tehachapifan

    tehachapifan TrainBoard Member

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    ^^This!^^

    I can confirm from personal experience that this (along with the speed step mismatch thing mentioned earlier) can, indeed, cause some serious wonkiness.
     
  14. 308GTSi

    308GTSi TrainBoard Member

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    Is it possible to remove the motor and connect it direct to DC and check it runs up to full speed ? It may not be the DCC regardless of brand or model. ..........and yes, I am still living in the 1980's. :)
     
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  15. Chops

    Chops TrainBoard Member

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    Don't you boys know anything? Simply refrag the alternate bustolion-phister from the reversing conjometer and reset using the alpha indexed jangonometer. Done. Fixed. Then throw the bloody thing over the wall.
     
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  16. 308GTSi

    308GTSi TrainBoard Member

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    That or oxy-acetelyne torch (also known as the blue tongue spanner) !!
     
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  17. Doug Gosha

    Doug Gosha TrainBoard Member

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    Turn it off, wait ten seconds, and turn it back on and see if that works.

    :D

    Doug
     
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  18. umtrr-author

    umtrr-author TrainBoard Member

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    Doug, you left out "did you plug it in?" :ROFLMAO:

    I have been playing with the board contacts to the frame all along and they do appear tight. I've also done several Factory Resets. The NCE Power Cab is set to 28 speed steps, but I need to check on the default setting for the decoder.

    It seems to me from the responses so far-- for which many thanks-- that some degree of disassembly is going to be needed. Oh, well.

    Now where did I put my flux capacitor?
     
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  19. Rich_S

    Rich_S TrainBoard Member

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    Hi George, All of my TCS decoders were defaulted to 28/128 speed steps. What value did you use for the factory reset? The documentation I have is a little confusing but seems to indicate a value of 2 programmed into CV8 will return the decoder to it's factory defaults. After doing the factory reset, does the locomotive respond to address 3? Can you change the address to a 4 digit address, lets say 1500 and will the locomotive respond to the new four digit address? What happens if you turn analog conversion off? If you've tried all these suggestions, plus verified the motor is isolated from the frame and the two DCC boards fig snugly into the frame, it maybe time to contact TCS. Please let us know what you find?
     
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  20. umtrr-author

    umtrr-author TrainBoard Member

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    Rich, there's two ways to factory reset: One is exactly what you said, which is set CV8 to 2. The other is through the NCE Power Cab which has a "recovery program" -- that's how I know that the motor "turns" that little fraction with each CV value set. I'm going to try the direct CV8-> 2 method just to be sure.

    I've also just looked at the CN-GP instructions downloaded directly from the TCS website, and the default is to 28 speed steps, so it's probably not that but it doesn't hurt to double check. The default is also to dual mode, DC and DCC, and I've not tried turning that off yet.

    I'd be farther along with this if not for the Day Job...
     
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