Digitrax Decoder for Kato SD40 (Non-DCC Ready)?

[Kisatchie]

I'm bidding on a couple of Kato SD40 N Scale locos, and the Digitrax site says use this decoder:

http://www.modeltrainstuff.com/Digitrax-N-HO-Scale-Wire-in-Mobile-Decoder-p/dig-dn136d.htm

It doesn't look like the decoders I've seen before (not that many), so I'm wondering, will it actually do normal decoder stuff and work in the SD40?

Thanks for any enlightenment.


Hmm... How Zen...

[reinhardtjh]

Hi Kiz,

  That DN136 decoder is what they call the "wired" type.  It's not a drop in board like most "DCC ready" locomotives will use.  If the Kato SD40's are old and not DCC Ready as the topic says, then these decoders will work okay.  Internally they do everything the others do, it's just a different format.  It takes more work to install so be prepared for that (unless you have an installer lined up, then they should be able to handle it).

Do you plan any special lights on this?  If not, you may want to try the DZ126 which is a Z scale decoder. The big difference is that it's smaller and therefore a little easier to install.  The width of the DN136 is about 10.6mm which might be just a tad wide for the SD40.  THe DZ126 is 9.4mm wide, which doesn't sound like a lot, but it can be inside the narrow hood of an SD or GP.  The other difference is that is has only 2 lighting functions instead of 3.  This means you get front and back lights and that's it.  The larger DN136 gives you front, back and one other (mars, ditch, etc).


DZ126 - http://www.modeltrainstuff.com/Digitrax-Z-N-HO-Scale-Mobile-Decoder-p/dig-dz126.htm

[Kisatchie]

Hi Kiz,

Do you plan any special lights on this?  If not, you may want to try the DZ126 which is a Z scale decoder. The big difference is that it's smaller and therefore a little easier to install.

DZ126 - http://www.modeltrainstuff.com/Digitrax-Z-N-HO-Scale-Mobile-Decoder-p/dig-dz126.htm

Thanks for the recommendation! If I win the SD40's, I'll go with the smaller decoder. I don't need any special lighting on the locos.


Hmm... Kiz will probably
try to make me install
'em...

[mmyers]

Simplest decoder installation for this engine  (and all non-dcc ready two light board engines) is the TCS CN or CN/GP. The original Kato SD40's will use the CN-GP decoder. These decoders still require a little bit of filing and solder but no where near the amount of work that the Digitrax will require.
http://www.tcsdcc.com/Customer_Content/Technical_Info/Tech_Manuals/TCS_Book_of_Classic_N_Installations.pdf
I put DN93's in mine about 20 years ago which reminds me , I need to change those out to something more modern and add weight in the leftover space. Maybe sound and a speaker...

Martin Myers

[reinhardtjh]

Martin has a very good point.  I'd forgotten that the Kato C30-7's had the chassis with the two small light boards that would work with the TCS CN-GP.  From the pictures on Spookshow.net it looks like the SD40's are the same for the pre-DCC ready versions so that TCS decoder would work for them as well.

Hold off buying the decoder until (if) you win the auction and get the loco so you can take the shell off and look.  That way you'll know for sure which decoder to get.  The trade off on the TCS CN-GP vs the Digitrax DZ126 is that there will be less chassis filing, but you need to do some soldering on the decoder with the TCS.  With the Digitrax, you will need to do more chassis filing but all the soldering will be on various chassis parts - motor, pickup leads, lights.

TCS CN-GP --> http://www.modeltrainstuff.com/TCS-N-CN-GP-3-Fun-BEMF-Decoder-Split-Lighting-Loco-p/tcs-1286.htm

[jagged ben]

Simplest decoder installation for this engine  (and all non-dcc ready two light board engines) is the TCS CN or CN/GP. The original Kato SD40's will use the CN-GP decoder. These decoders still require a little bit of filing and solder but no where near the amount of work that the Digitrax will require.
http://www.tcsdcc.com/Customer_Content/Technical_Info/Tech_Manuals/TCS_Book_of_Classic_N_Installations.pdf
...

Martin Myers

Yes, this is what I did in mine. 

[ntex]

I have installed the TCS Cn and CN-GP decoders in older Kato and Atlas locos with good results. A much easier install than the Digital Dz or Dn decoders.

[Kisatchie]

I have installed the TCS Cn and CN-GP decoders in older Kato and Atlas locos with good results. A much easier install than the Digital Dz or Dn decoders.

Did you have to mill the frames? How much soldering? I won 2 Kato SD40s (pre-Dcc), so if I can install decoders myself, that would be nice. Otherwise, the search begins for someone who can do it for me... LOL.


Hmm... don't look at me,
Kiz...

[Kisatchie]

Still hoping to hear if the frame on the SD40 has to be milled to fit the Digitrax DZ126 decoder:

http://www.modeltrainstuff.com/Digitrax-Z-N-HO-Scale-Mobile-Decoder-p/dig-dz126.htm?CartID=2


Hmm... I'd just cut away
all of the shell that
interferes with it...

[Missaberoad]

Still hoping to hear if the frame on the SD40 has to be milled to fit the Digitrax DZ126 decoder

Short answer is yes... Checking with my calipers There's lots of room (after milling) but you would have to mill away some of the frame to get it to fit.
Having never done such a conversion I'm not sure, but you may also have to mill passages for the wires?

It does look like it could be accomplished with a razor saw and files however...

[djconway]

I have done a few of these.  The first 2 were with Aztec frames, the next 4 were with home modified frames.  I basically followed Aztec's procedure but cut down the frame over rear gear tower to  fit the decoder.  I'll try to get a photo or two to show the process.

[rrjim1]

When install a TCS CN I still mill slots in the frame for wires, it makes for a much neater job, IMO.   

[reinhardtjh]

Still hoping to hear if the frame on the SD40 has to be milled to fit the Digitrax DZ126 decoder:

http://www.modeltrainstuff.com/Digitrax-Z-N-HO-Scale-Mobile-Decoder-p/dig-dz126.htm?CartID=2

Yes, some.  If you want to avoid even that, there are the Aztec milled frames.  $10 each plus shipping. You have to send your frames in though which means disassembly and stripping of parts. 

http://www.aztectrains.com/dccframes.html  - scroll down to the Kato section.  The TM3002 is what you want.

Instructions are here so you can see what you're getting into: http://www.aztectrains.com/Resources/TM3002.pdf

Note the diagram only shows the changes to the Kato circuit boards, it doesn't show the Orange and Grey wires which need to go to the motor brush caps (as mentioned in the instruction text).

[mmyers]

Short answer is yes. Milling (cutting) is required. You will need some space for the decoder. You will need a (trench) along the top of the frame for the 4 wires to the front head light and motor. You will need to cut a groove for the motor wires to get them to the brush caps. I also like to cut a little material out around the brush caps for extra clearance and still use kapton tape to insulate.
You will also need to cut the traces on the light boards to isolate the LED's and their resistors from the frame. This is much easier with a DZ126. I did my first couple back in "97 with DN93's. They still run well but probably should think about upgrading the decoders.
If you look at the photo on This page from Aztec, you will get a pretty good idea where the frame will need to be modified. It's a LifeLike engine, but pretty much the same design as the Kato. http://www.aztectrains.com/dccframes.html

Martin Myers

[peteski]

In my opinion, for the price Aztec milled frame is the best, easiest, and the most elegant solution.