Bachmann Class 108 - Lights issue

[Ray H]

I've just fitted Bachmann 36-553 eight pin decoders to both the trailer and power car of a Bachmann Class 108. I've tried each decoder in either coach. I've set up the direction of the trailer car by altering CV29 to get the correct head/tail light display relative to the power car and direction of travel.

 

Everything is hunky dory save for one strange thing!

 

I am using an NCE PowerCab and with the speed step set to an odd value - e.g. 1, 3, 5 etc. - neither the interior lights head/tail lights work in either direction.  The same applies if the speed step is 0, i.e. when the unit has just been selected or is at rest - most annoying as I use the lights to see which way the train is going to move! The lights appear to be functioning as expected if I use even values (other than 0) - e.g. 2, 4, 6 etc. (We'll temporarily ignore the fact that the power car interior lights aren't working at all but I believe this is associated with the contacts to those lights inside the car that I'll look at separately and the main problem was evident when I tested the both cars with their bodies off.).

 

I don't have (and haven't had) this problem with a Bachmann class 105 which is also dual decoder fitted albeit with different decoders.

 

The same problem applies if I have just one of the two cars on the track and applies on my programming track and on the layout in general.

 

I purchased four decoders at the same time. The other two have gone into locos and they're working as expected.

 

I'm off to try and address the interior lights issue on the power car whilst I wait for feedback. I have a different manufacturer's decoder that I'll also try whilst I have the body off the power car.

 

Has anyone any idea what might be causing this?

 

 

 

[Ray H]

Update.

 

I've removed the body from the power car to attend to the interior lights.

 

Consequently, I've been able to temporarily fit a Zimo MX60 eight pin decoder and the head/tail lights work as expected regardless of the PowerCab speed setting. However, the trailer car, still with the original Bachmann 36-553 decoder fitted continues to only display head/tails lights at even number speed steps on the PowerCab.

[Xerces Fobe2]

I got caught with a similar issue with a Class 108 and the trailer car. The problem my case was that the chip in the driving car was a 4 digit address whist in the trailer on 2 digit address so a 108 address code did not work.

 

Worth checking for though.

 

XF

[smokebox]

I think it's related to the number of speed steps selected, you have to use the same speed step settings on the decoders and the controller.  Maybe you've accidentally programmed CV29 with an incorrect value. 

CV29 calculator

[Ray H]

Thanks for the responses and apologies for the delayed response. I was summoned to daughter's house to do a Just job - as in "Dad, can you Just do (this)?"

 

To the best of my knowledge I have only adjusted CV29 for the trailer so that the head & tail lights work the opposite to the power car. I set the value to 7.

 

I shall try writing 08 to CV8 to reset the decoder and see what happens.

[Ray H]

I reset the decoder to the factory defaults and all is now in order. Thanks for the pointers.

 

Interestingly, unlike the Class 105 where if I recall correctly I had to change the "direction of the trailer" to get the head & tail lights to work correctly, this doesn't appear to be necessary with the Class 108.

 

The other interesting thing is that it was only the lights that were affected, the unit kept moving continuously (when appropriate) regardless of the speed setting.

[Grovenor]

Usually this sort of lighting problem comes about because either the command station or the decoder is set to 14 step mode and the other to 28 step mode, the lighting commands are different in each case. Unless you have some really old decoders  set everything to 28 or 128 step mode and then this should not happen.

Keith

[Ray H]

Thanks Keith.

 

I didn't knowingly change the speed steps on either. Aside from changing the decoder short address from the default of 3 and reversing the direction on the trailer decoder - unnecessarily as it transpired - I left everything as it was.

 

Knowing that writing 8 to CV8 resets the decoder, I wonder if I mistakenly set CV29 to 8 (instead of 7) when changing the direction on the trailer car's decoder. That would have the impact of leaving the direction alone but altering the speed steps to 14 on the decoder whilst the PowerCab stayed at 28. Your comment that such an incompatibility would affect the lighting circuits probably accounts for why there was no apparent problems with the movement activities - I presume the decoder wasn't responding to alternates steps.

[Grovenor]

Ray,

That sounds like a very possible scenario, you could always try replicating it (g).

Regards

Keith