Wiring diagram for 4-4-0 light board

[bnbayer]

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

[Len]

The markings on older Bachmann light boards are fairly consistent. Not all boards have all of these connections:

R: Right Rail Pick-up
L: Left Rail Pick-up
M+: Motor Brush Connected to Right Rail
M-: Motor Brush Connected to Left Rail
L+: Light Positive
L-: Light Negative
B+: Battery Positive*
B-: Battery Negative*
*Some boards allow the addition of a reed switch On/Off controlled battery pack for operation, rather than using track power.

Len

[bnbayer]

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