P2 Cock O the North - Lights

[GoGoffa]

Hi. I fitted 2 x LED headcode lights and a tender light to my P2. There was a couple of problems. 1 - the lights operated in reverse to the direction of the loco. The yellow and white leads were correctly connected to the decoder 8 pin socket. 2 - the lights switched off when the loco came to a stop or very slow speed. Had to hit F0 each time the loco moved to switch lights back on.

Controller - NCE powercab.

 The solutions after a lot of trial and error and blogging on RMweb was:-

1 Reversed the yellow and white leads, best done at the decoder cct board connections so 8 pin socket remains correctly wired to NRM standard.

2 Reconfigured CV29 from 38 to 36.

Now the lights operate as desired. Now a happy P2 operator. A great loco.

[Fishmanoz]

Hi GG, welcome to the forums.

 

Admin, this thread should be in DCC.

 

You really do seem to have a case of the back to fronts, in more ways than one.  Just to say how things should work, the forward direction lights should be connected to the white wire, both front and rear lights that you want on when the loco is travelling forward.  The rear direction lights are connected to the yellow wire.  Once you switch this lighting on with F0, they should automatically illuminate depending on loco direction.  Is that what you now have?  If you want to check out more detail, go to Brian Lambert's site, DCC section then lighting where he explains it with diagrams. 

 

The other back to front is your CV29 setting.  Directional lighting only operates when you have 128 speed steps turned on at bit 1.  With your original value of 38, turned on you have 128 speed steps (2), DC running (4) and long address (32), giving your total of 38.  By reducing it to 36, you've turned off the speed steps so you should have turned the lights off too.  Very strange.

[GoGoffa]

Hi GG, welcome to the forums.

 

 

Hi Fishmoz.

Strange to say the least. I have 15 locos which I have fitted sound decoders, lights etc. The new wiring was coded correctly, white for forward lights and yellow for those for reverse, but when activated the lights were in reverse, so to fix I did not want to reverse the wiring at the 8 pin socket and as the direction cannot be changed by manipulating CV's as with the ESU decoders, I changedthe connections on the decoder board. Light direction then as desired.

As for CV29, its beyond me. With the value at 36, the loco runs in the correct directions as demanded by the hands set, Still 128 step speed control, and the lights stay on when the loco stops and change direction when the loco changes direction. Yes strange, but why care, it performs just as i want.

Cheers

.

  

[96RAF]

I presume we are talking about a TTS decoder in which case it is well known that early decoders had reversed directional lighting logic, easily solved as described earlier by swapping the yellow and white wires at the decoder, easier than trying to do it at the decoder plug, and keeping the loco side wired to NMRA standards.