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



## jimtyp (Jan 2, 2008)

Anyone install a Decoder in the Bachmann K-27 yet?  Something that doesn't have a direct socket that is?


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## StanleyAmes (Jan 3, 2008)

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


www.tttrains.com/largescale


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## jimtyp (Jan 2, 2008)

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?


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## Tom T (Jan 2, 2008)

Jim, 

While awaiting Stan's response, I can see that it would be easiest to hard wire a decoder to the solder pad on the side of the main tender PC board. Unless you have a source for 
plugs that will fit the sockets supplied, which the 'Dummy Board' plugs into. The dummy board as I read it, is a board with a couple of IC's and resistors (or inductors) on it, which allows DC operation 
provided the switches are properly configured. My belief is that if one soldered to the pad, then one would remove the dummy board in order for the loco to function. I am not aware of any of the aftermarket suppliers (Digitrax, NCE, et-al) yet supplying plugs to fit the BM socket. On this last point I stand to be educated. 

Regards, 

Tom T. 
Bermuda


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## StanleyAmes (Jan 3, 2008)

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.

OR

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.

Stan
www.tttrains.com/largescale


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## jimtyp (Jan 2, 2008)

Stan, thanks for the info.  However, now I have more questions, I guess that means progress 

The solder pads on the dummy socket sound like a good way to go.  BUT how do I know which wires from the decoder to solder where on the dummy socket?  When I pick up the loco (hopefully tomorrow) will it have diagrams for this?  Or do you have any detailed pics of the dummy socket and what wires would be soldered where?  For the motor + and -, and lights?

_*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.

*_I will be using DCC but not sure where the inductors are?  How do I know where the small traces are that need to be cut?  Again, any detailed pics of these particular items or will there be instructions and a diagram included with the loco?


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## Dave Crocker (Jan 2, 2008)

And Stan, could you post your solution now on interfacing to the Phoenix 2K2 board.


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## jimtyp (Jan 2, 2008)

Dave, are using DCC? I was going to use a P5 for DCC. Is there a better solution using DCC with the 2K2?


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## bobgrosh (Jan 2, 2008)

Note to all: 
Remember, there have been no specifications published as yet for the Kay. 
It is supposedly designed to match the Aristo plug. In theory, one could remove the dummy board and plug in the DG583AR or the DG383AR. 
Since we do not know what the current draw is on any of the function leads or the DC common (+) or DC Ground (-) Or the Motor, I would strongly remind you to put the 120 ohm - 2 watt resistor in one track lead before applying power. See the Digitrax DCC Decoder manual for details. The resistor should have been suppled with you startup set. 

Personally, I would not be cutting any lands on the dummy board to install the decoder as the whole purpose of removing the dummy board in DCC is to isolate the motor and other circuitry in the loco from the track and each other. One would need to be very sure of the locos, socket, and plug wiring prior to skipping the important step of removing the dummy plug or inserting the limiting resistor in the feed to the track. 

B0B


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## jimtyp (Jan 2, 2008)

Is the best option for me then, because I have an NCE decoder, to ditch the entire DC board and solder the motor decoder wires to the correct motor and light wires directly?


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## Dave Crocker (Jan 2, 2008)

I'm looking for the interface between Bachmann's optical chuff sensor and a Phoenix sound card.


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## bobgrosh (Jan 2, 2008)

Depends on what you mean by best option 
You can not solder directly to the motor and light wires in the tender. They are in the loco. You would have to put the decoder in the loco. Keep in mind, that the light function connections in the tender do not connect directly to the lights, they are simply on/off inputs to the real lighting control boards. At least some of these must be in the loco. 

You can probably do a sort of plug and play installation by connecting the NCE decoder to the plug board in the tender and removing the dummy board. There are solder pads on the plug board. 
Putting the decoder in the tender will only give you primitive control over some functions. At this time I don't see how any of the FX functions will work or any of the locomotion effects from Soundtraxx will work. All of this is just speculation since nothing has been published. Until Mine gets here, I can't say for sure how difficult a complete install will be. There is no word as yet if the smoke generator is able to be controlled from solder pads on the socket board. Most of the questions I have asked have been met with "a function decoder installed in the loco will have to be added." 

It looks like connecting to the socket board only provides for only the very primitive installs where the motor runs and the headlights change or maybe some other lights might be turned on or off. 

Of course a lot of the stuff is like the Shay, as TOC said, "Yank out board and toss it." I replied that: "I would keep the card in the Shay, It provides all the tie points for that mass of wires." 
Naturally TOC was right. Most of the wires came off the card anyway, Had to rewire most stuff to get it to work, When I got ready to button it up, I realized the stupid card was in the way, and all it was doing was tieing the four wires from each truck together, And naturally, one of them had a bad solder connection, so I ended up tossing the card and just soldering the wires together and heat shrinking them. God I hope it's not that bad with the Kay. It would be really nice to be able to swap decoders from one loco to the next at times. 

On the bright side, I've confirmed with Digitrax that the new SFX0416 sound decoder takes a 0 to +5 or higher signal to activate the chuff. 
to quote from the Digitrax site: 

And, this additional bit from AJ: 

For the Digitrax sound CAM input signal, all that is required is a source of voltage that goes "on" (above about +5V) and then "off" (no voltage for e.g. 10mS). The actual DCC track side is not critical. The only issue would be for DC operations when the track connection in one direction makes the signal always negative and unreadable. For operation on DC then, the cam signal will need to have a +ve power supply level, as e.g the new Bachman K27 seems to have. 

Woopeeeee! no transistor to wire in. 

So far, it seems to be the only sound decoder that does not need a transistor. At least it is the only one any manufacturer will confirm for me.


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## Tom T (Jan 2, 2008)

Bob, 

I hope you get your locomotive today! Mine came in from St.Aubins last Friday, and while I've not had the time to DCC it, I have spent a little time getting my head around the install. I have a 583S in stock, so will use that initially, if for no other reason than to stop the analog buzzing. The idea is to add sound later, once I know more about it. I'll be using the solder pad on the R/H side of the main board in the tender, and removing the 'Dummy'. Believe it or not, everything is in the tender. There are two plugs coming from the loco to the tender: One has 6 pins, the other 7 pins! The solder pad and the dummy plug ins have just about every possible connection you could want, and it's all in the tender. I honestly believe (and I am an ardent follower of TOC's rip & toss method) that DCC'ing, or sound equipping this loco would be more work than it's worth NOT to use the facility in the tender. Bachmann have made a quantum leap with the wiring in this loco. It may not be perfect, and I'm sure that there some of us out there who will come up with all sorts of fixes and improvements, but it's one heck of a lot better than the earlier locomotives when it comes to modifying the power and control systems. 

Regards,


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## StanleyAmes (Jan 3, 2008)

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.

Stan
www.tttrains.com/largescale


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## bud (Jan 10, 2008)

Stan, I realize that this is mostly for DCC, but I am going to install a 75mhz Aristo on board in the K when I receive it.
Will it simply plug in or is the socket different than the Aristo socket?
Bud


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## jimtyp (Jan 2, 2008)

Stan, have any pics of what you described? My K-27 is in and I pick it up today. I'll see if I can figure out where what is what, but pics of what you describe would be very valuable


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## bobgrosh (Jan 2, 2008)

Posted By Tom T on 01/04/2008 6:21 PM
Jim, 
...
... I am not aware of any of the aftermarket suppliers (Digitrax, NCE, et-al) yet supplying plugs to fit the BM socket. On this last point I stand to be educated. 



Digitrax supplies two decoders that match the Bachmann pin arrangement. Note however that some pins on the Digitrax decoder are not connected to anything in the decoder. For example, On J1 there is a pin for the chuff cam. Since there is no sound on the CURRENT versions of the two Digitrax cards, so, this is not a problem. The chuff circuit output does not interfere with the operation of the motor decoder, and the motor decoder does not interfere with the chuff output.

The same is true for the pins on J2. There are no connect ons inside the decoder to these pins. There are additional WIRED decoder outputs that may OPTIONALLY be wired up. These could be wired to the solder pads on the Bachmann plug boards, or you could solder the desired function outputs to the DECODER J2 pins. Soldering the decoder output wires to the decoder pins has the advantage of making the decoder completely plug and play, simply unplug the decoder from the socket, and plug in a different one, or even the dummy board to instantly convert the loco back to DC.


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