Trainman203: I don't use automatic sounds, either. Perhaps if you're operating in DC and there's no other way to control them.

Brian: Thanks for this. The 4-4-0 isn't exactly like this, but it may help to figure things out.

This should be the reference for my loco:
https://soundtraxx.com/content/Reference/Factory-Installed/Bachmann/Spectrum/ho_modern4-4-0.pdf

I have a Spectrum Modern 4-4-0 (bright blue box, "DCC Sound On Board"). Can I get a wiring diagram, or a list of the 6 coloured wires and what they do?

Also, various reviews mention that this model has a cam for synchronising the exhaust chuffs. I've tried CV112=128 (Bit 7 on) and the default zero. Neither seems to have any effect. Does this loco actually have a cam? How do I activate it?

It sounds like the decoder isn't detecting the DCC signal, and thinks it's on a DC layout. It's running away at 14 volts DC - maximum speed - and the sound is on as it would be on DC. No control because it doesn't see the DCC signal.

Not sure what caused this, but it might have been the combination of plugging and unplugging the controller. (Shouldn't cause a problem on most DCC systems, but...)

Did you try turning off your DCC system and re-booting? Do you have any other locos, and are they working normally?

If you have to reprogram, do a factory reset of the decoder first. I also set CV29 to NOT run on analogue (DC) power, to prevent runaways like this.

Brandon

Thanks, Len. That's very helpful... and the board is now making some sense. My loco doesn't have the battery option, but it has two sets of L+ and L-, one of which isn't used: there's no backup light on the tender of this loco.

There's also a third "R" pad at the far end of of the board with a black wire soldered to it. I was confused about that, but I see now it's just the wrong colour wire for the rear tender truck R pickup.

Thanks again. I can do this.

Brandon

Hi,

I have an older HO 4-4-0 Modern Richmond loco, model #83402, on which I would like to install sound. To avoid smoking a new decoder (!), I would really like to find a wiring diagram for the original Bachmann light board. Mine is not the same as the one I've seen on-line in some installation guides.

I'm pretty sure some of the red and black wires are power from the rails, but the pads marked M+, M-, L+, and L- (brown, yellow and orange wires) are a mystery. Which to the motor? Which to the headlight?

Any help would be appreciated!

Thanks,

Brandon