Sound decoder problems

[Potrail2378]

Hi, around six months ago I converted a Hornby (ex Lima?) class 37 to DCC and fitted directional lights, everything worked perfectly.

I treated myself to the R8102 sound decoder, but am having problems with it. All the sounds work OK but it won't move! There is no handbrake release noise. The directional lights come on white at the front and red at the rear, but when I change direction on the Hornby Select, the lights stay the same way and don't change. It's a plug/socket affair so I put the old decoder back in, but now while travelling forward there are no directional lights and in reverse the directional lights work fine.

Not sure if I've broken a wire along the way, or if there's a fault with the sound decoder. Any thoughts please?

Thanks in advance.

[ColinB]

The Lima motor is a bit marginal for the TTS decoder, the TTS decoders maximum current is 500 mA, Lima motors can draw in excess of this. That still doesn't explain what is going on. It is as if the Select is not sending out the reverse command. I know I am always saying this, but that is why I bought a decoder tester. I assume it all worked with a normal decoder before you put the TTS decoder in. The only thing I can think of, is you have got a wire mixed up.

[Potrail2378]

Yes, everything worked perfectly fine before I tried the TTS decoder. The Select in the workshop works OK as far as I know. I will have to take the loco upstairs to the loft layout where I have a Hornby Elite. Hopefully I have just broken a wire while swapping decoders.

[96RAF]

This is where a decoder test rig comes in handy to prove the decoder is good or not. If it is good in the rig, then you can confidently look at the loco for the fault.

I would suggest there likely is a wiring problem. For the logic to stay the same way at direction change it suggests a decoder problem, but you are unlikely to see this on both decoders, pointing back to the loco.

Are your lights LED or filament, home brewed or a kit. As you have a socket in your loco is the decoder plugged in the right way round.

TTS decoder needs certain settings to work properly, e.g. CV3&4 both set to value 15, 128 speed steps in CV29, etc. A decoder reset using the Elite should put it back to these settings and put the address to default of 3.

[Potrail2378]

Hi 96RAF,

I have fitted Tower LEDs at 3vDC with a 1Kohm resistor in series for each LED. They are not from a kit, but from what I have made up. Everything was working fine.

However, now that I have had time to go up to layout in the loft, where the Elite is, it seems to be working fine, apart from a slow speed jittering which I can easily remidy by altering the CVs. I will have to swap the decoders again to see what happens, but right now, it's OK. I will also have to check the socket and wiring in the loco.

I will keep you updated.

[96RAF]

Thanks for the update. Good luck with it after you swap decoders again. You could try an extra 1k ohm res in the blue wire to further control the current.