the MRH Forum

On30 Rail Truck circuit board Locos and rolling stock
Reply
New member 14 posts rxalph New member 14 posts
rxalph

Anyone have a schematic or a pin diagram for the pcb included in the Bachmann On30 rail truck? Need to know which solder pads get track power, motor, and lights wires. Model completely disassembled for painting and all wires broken and/or shorted. Its a long story.
Reply 0
marcfo68 Frequent poster 656 posts
marcfo68

. . .

Found this via Google

http://www.girr.org/girr/tips/tips8/bachmann_railtruck_tips.html
Reply 0
Brent Ciccone Brentglen MRH Author 980 posts
Brent Ciccone Brentglen

Wire Colours

Don’t go by the wire colours, they are basically random. Test with a meter or small battery to confirm.

Brent Ciccone

Calgary
Reply 0
efehser Active Member 52 posts
efehser

Bachmann

Never used standard color codes, so you'll have to trace. Their boards were/are usually marked, very small, as to what goes where. IIRC, the rail truck uses an 8 pin connector, so you can back-trace from that.

Eric

Modeling On30 and proud of it. There is a jar of rivets on the workbench if you feel the need to count.
Reply 0
rxalph New member 14 posts
rxalph

Rail truck tip

00011(1).jpg 

great site, unfortunately that was for 1:20.3 model. This is a very different beast.

All the wires in the model are black until the decoder side of the 8 pin plug.

In this picture the dental pick is pointing at what I think is power input. Other pole would be the spot opposite. There are wires from front truck and rear axle to pick up track power. The 3 spots on the left end are where the headlight wires were and the spots on the corners are motor connections. Not sure where the taillight wires connected. I suppose I could trace back from the 8 pin plug known colors and check to see if there is continuity to the proper solder pad?
Reply 0
efehser Active Member 52 posts
efehser

Trace back

From the 8 pin is going to be your most accurate way to find what is where. A possibly better alternative is to hardwire. That board is an old design with RFI suppression that can be problematic with some modern decoders.

Eric

Modeling On30 and proud of it. There is a jar of rivets on the workbench if you feel the need to count.
Reply 0
Jim at BSME Prolific poster 2,105 posts
Jim at BSME

Picture

If you could make a bigger picture that would help here, agree the two corner pads are for the motor, hence the M+ and M- labels on the traces. I can not read what is on the trace to the pad the dental pick is pointing too, at least I think there is something just above the M-. Anything on the bottom of the board?

Did you have a decoder plugged into this? I don't see the jumpers in the DCC 8-pin connector for DC operation.

Since we know where the motor connects you can trace them back to the 8-pin connector and from there figure out the others using the stand NMRA 8-pin decoder connections.

https://dccwiki.com/File:NMRA-8pinwiring.png
- Jim B.
Baltimore Society of Model Engineers, Estd. 1932
O & HO Scale model railroading
Check out BSME on: Facebook, Instagram
Reply 0
rxalph New member 14 posts
rxalph

Thanks Jim

Did the trace back from each pin and found the solder pads to be as I had previously posted. While there is not continuity from pin 6 to pin 2 they both individually connect to the same solder pads. My WAG is that the polarity is reversed by the decoder so that front vs back light is selectable. This being a converted road vehicle I won't worry too much about it and all the lights will be on all the time. 

The model came with a decoder labeled Bachmann part #44915. Will keep that until ready to add sound functions.

Happy Rails to You.
Reply 0
Reply