Model Railroading > Decoder Problem It works fine until....

I have a pair of Kato N Scale RS2's that I am putting Digitrax plug n play decoders in.  Great installation, everything works fine until i snap the shell back on.  I can literally leave it up on just one end and it still works fine.  Until you hear that final click to lock it in place.   There is nothing obvious that is causing this.  I've had the shell of half a dozen times and moved the board around.   

Any ideas?

Suggestions greatly appreciated!

Dave

Sounds like wiring being pinched when the shell is all the way down.

Could be a pinched wire as mentioned above, but a couple questions come to mind...

Are you losing all power or just motor power (i.e. do you still get lights)? Also, are you getting any signs of a short?

While I've never installed a decoder in that particular loco, my experience with N scale installs if all power is lost when the shell is on (and there's no signs of a short) is that the shell is sometimes putting downward pressure on the decoder somewhere, possibly breaking the contact points between the decoder and the frame. This downward pressure can also cause a potential short with some installs, by causing a component or other exposed point to contact the frame that wasn't making contact with the shell off (or with an exposed wire to support the pinched wire theory above). Also, did you wrap Kapton tape around the bit of frame that is directly above the motor, where the motor contact "wings" come off the decoder and then extend down (assuming you're using a decoder with these wings)? A short between the motor and frame is often fatal for a decoder and this is a potential trouble spot on many installs.


 



Edited 1 time(s). Last edit at 06/27/20 13:55 by tehachapifan.

Definitely use Kaptan tape to insulate it like tehachapifan suggested. I once bought an engine fairly cheap from a seller on eBay that said that the engine didn't run. It was a model noted for not running properly so I took a chance. As it turned out, the seller had installed a DCC decoder that shorted out on the frame. I removed the decoder and it ran fine. But I am left with a shorted out decoder now.



Edited 1 time(s). Last edit at 06/27/20 14:15 by tramfan.

Yes, using the kapton tape.  No, no exposed wires.  Its a plug n play so no wiring needed.   I,m thinking the shell is pushing down on the decoder board causing it to loose contact.   All I can say is, what a pain in the arse!

Dave

Are there any metal lift rings or anything else that is metal poking through the shell over the decoder?