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Anyone install a Decoder in the Bachmann K-27 yet?

3754 Views 16 Replies 6 Participants Last post by  bobgrosh
Anyone install a Decoder in the Bachmann K-27 yet?  Something that doesn't have a direct socket that is?
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yes several different ones easiest is to use the dummy socket as the wiring point or you can use the pads at the sides.


Stan, does the dummy socket come with the loco? Will the dummy socket work with an NCE motor decoder? I assume it will need some minor soldering since the socket that comes with the NCE only has a socket on one end and the other end is just wires?

The K27 has a socket in the tender with a dummy plug installed for DC operation and a row of solder pads next to the socket.  If you have a product designed for the socket you unplug the dummy plug and replace it with the new product.

If you have a device with screw terminals you remove the dummy plug and make connections to the solder pads.


you use the solder pads on the dummy socket and adapt it to your use and replug it in.  I am using this second approach more often now.

For DCC use simply remove the inductors on the bottom of the board to isolate the motor and cut two small traces on the front top of the board to isolate the headlights.

Then install wires from the socket to the board of choise.

A raw DC + and - is needed for full operation.  Most decoders have this  If not simply continue to use the rectifier on the dummy plug for the DC.  Connect the motor leads, the track leads, the function leads and the decoder common + to the locomotive + and then plug the dummy plug back in

Hopefully we can get some conversions published soon.  Tryig to convert mac files at present.

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Tim, Tom, Dave, Bob

Having done a wide variety of DC, DCC, and RC installs in the K27 I find that there are several equally good methods for installing control systems. You can use the solder pads on the side or use the socket, either works.  If your control system does not yet have a native plug in device you can still use the dummy plug to make the connections.

I tend to prefer using the socket for the control system of choice and the solder pads for the sound install but either works.

One of the key things to remember is you need to supply both DC plus and DC ground to the K27 for full functionality.  If your control system of choice does not provide both, then simply use the dummy plug to provide the DC.  Remove the inductors from the underside of the dummy plug to isolate the motor and if desired cut the traces to the light pins on the top to isolate the front and rear lights.

Then you simply install 2 power/signal inputs, 2 motor outputs, the front and rear headlights and then up to 4 additional functions if desired.

If your control system does not have native sound then it is easy to add an after market sound system.

If you want to use the K27s optical chuffs then you need to determine if your sound card requires a ground trigger or can work with a 5 volt positive trigger.  The K27 provides the later.

If you need a ground trigger simply use an NPN transistor to invert the chuff trigger.

Install a NPN transistor on the K27 main board in the tender.   Almost any NPN transistor will work.  A suitable one that is easy to install is Radio Shack #276-2017.  At the side of the K27 main board in the tender are solder pads with holes. Transistors have three pins.  One is Base, One is the Collector and the third is the Emitter. Refer to the package your transistor came in to determine which pin is which.  Insert the base pin of the transistor to the K27 chuff output (J1;5), and the emitter pin of the transistor in the ground connection (J1:7).  Solder the chuff trigger of your sound board to the collector pin on the transistor.  You normally also need to common the trigger ground from the sound board the ground pin on the K27 for the trigger to work.

As we progress expect to see more and more control and sound systems that are Plug and Play.  But you can always easily install any that are not plug and play by connecting the appropriate wires.

Hope that helps.

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