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DC Works; DCC Doesn't

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  • Member since
    February, 2018
  • From: Moxee, WA
  • 6 posts
DC Works; DCC Doesn't
Posted by dcb_13 on Friday, January 11, 2019 3:57 PM

Hello. I have a RTR locomotive that work fine in DC, but when I install the decoder, it has a faint click, and my system turns on and off. I checked the decoder in another locomotive that I knew worked, and it was fine. My question is does anyone know what is causing this, and can it be fixed? I would like to hold on to the locomotive, but I don't want to get in too deep with it. Thank you in advance for any advice.

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  • From: Northeast OH
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Posted by tstage on Friday, January 11, 2019 4:38 PM

If your DCC system is turning on and off then you have a short somewhere.

Is the decoder plug 'n play - i.e. is it press fit into a NMRA 8-pin socket or harness plug?  Is the decoder wrapped in heat shrink, or open (unwrapped)?  If the latter, you might see if the decoder is shorting to the chassis somewhere.  A piece of Kapton tape on either the underside of the decoder board or the chassis should help that.  You might want to check if any wires are shorting to the chassis.

Lastly, which decoder are you using and which locomotive are you installing it in?

Thanks,

Tom

http://www.newyorkcentralmodeling.com

Time...It marches on...without ever turning around to see if anyone is even keeping in step.

  • Member since
    February, 2018
  • From: Moxee, WA
  • 6 posts
Posted by dcb_13 on Friday, January 11, 2019 4:48 PM

Tom,

Thank you for the quick reply. I installed it in an Athearn RTR NS SD60. I don't know the model number off the top of my head. Yes, it is a quick plug. And yes, I have the decoder wrapped in electrical tape. It has to be the locomotive then, because I don't have this problem with any of my other locomotives. I will start with the locomotive and see what I can find.

Best regards,

David

  • Member since
    December, 2015
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Posted by BigDaddy on Friday, January 11, 2019 5:33 PM

If the OP is swapping the decoder back and forth, I'm going to go out on a limb and suggest it has an 8 pin plug on it. 

The plug can be installed 180 degrees backwards.  I don't know if it would still click, but the engine would not run if it was backwards.

Almost never can you give us too much information about your problem.

Henry

COB Potomac & Northern

By the Chesapeake Bay

  • Member since
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  • From: From Golden, CO living in Puyallup (Seattle), WA
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Posted by Renegade1c on Friday, January 11, 2019 5:40 PM

What type of connector?. Better yet what brand of RTR and locomotive type? If its an athearn RTR it can use either a 8 pin or a 9 pin connect to attach decoder. If you are using the 8 pin connector you have to remove the dummy board from the 9-pin connector. If you are using the 9-pin connector to attach the decoder than something else is wrong. 


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http://www.coloradofrontrangerr.com/

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  • Member since
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  • From: Reading, PA
  • 25,324 posts
Posted by rrinker on Friday, January 11, 2019 7:33 PM

 Putting the 8 pin plug in backwards just makes the loco run backwards. The 8 pin pinout is such that pluggin in backwards won't break anything. The 'polarity' of the incoming DCC doesn't matter, and putting the plug in backwards swaps the track inputs, the motor outputs, and the front and rear light.

 If his is an Athearn loco, almost certainly the previous post is the issue. The dummy plug is on the 9 pin connector, but if you plug a decoder in the 8 pin socket you need to remove the dummy plug from the 9 pin. Depending on the decoder, the wires may unplug from the decoder and you can connect the decoder to the 9 pin instead of the 8 pin.

                                        --Randy


Modeling the Reading Railroad in the 1950's

 

Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.

  • Member since
    February, 2018
  • From: Moxee, WA
  • 6 posts
Posted by dcb_13 on Friday, January 11, 2019 7:39 PM

Dummy decoder is removed. 9 pin is on correctly. 

It is an Athearn. 

  • Member since
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  • 775 posts
Posted by betamax on Saturday, January 12, 2019 6:27 AM

dcb_13

Dummy decoder is removed. 9 pin is on correctly. 

It is an Athearn. 

 

This page has a troubleshooting process for the 8 pin plug.  All you need is an ohmmeter:

https://dccwiki.com/8_Pin_DCC_Plug

It is always possible that something was wired incorrectly at the factory. It does happen.

 

  • Member since
    February, 2005
  • From: Vancouver Island, BC
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Posted by selector on Saturday, January 12, 2019 10:58 AM

dcb_13

Dummy decoder is removed. 9 pin is on correctly. 

It is an Athearn. 

 

 

????  Decoder....or plug?  If the decoder is correctly wired per reasonable instructions, then somehow your motor's brushes are not isolated from spurious/unwanted power pickup.  Or, a wheelset may be installed backwards?  Truck reversed...somehow?

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  • From: Ontario Canada
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Posted by Mark R. on Saturday, January 12, 2019 6:14 PM

dcb_13

.... And yes, I have the decoder wrapped in electrical tape. ....

Best regards,

David

 

Wrapping a decoder in electrical tape is not a good idea as it will keep the heat in - not something you want to do. Not saying that has anything to do with your problem, just that you should not do that.

Problem at hand .... just to verify - your decoder is plugged into the 9-pin plug and there is nothing in the 8-pin socket ?

Mark.

¡ uʍop ǝpısdn sı ǝɹnʇɐuƃıs ʎɯ 'dlǝɥ

  • Member since
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  • From: St. Paul
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Posted by garya on Saturday, January 12, 2019 6:41 PM

Does it look like this? 

I assume this is what you mean by 9-pin dummy decoder. Have you tried a different decoder? 

Gary

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