Not too bad

Unless they've changed the drive since I bought mine (I have two Trainman GP39-2s and several GP38-2s, but haven't bought a new one in several years), you can use a board-replacement decoder and cut a bit off the rear weight to make room for a "sugar cube" speaker.

Scott Chatfield

A great place to start is..

with a 21-pin Decoder and to make the wiring easier and straightforward and the job much neater try a Decoder Buddy.  I’ve done a number of my own Atlas locomotives of all eras.

Left to right;  Cut off overhang, place Decoder Buddy with Kapton tape, groove rear weight for routing track wires from rear truck to Decoder Buddy, add Scale Sound Systems speaker with rubber cement or Goo, solder in track wires, speaker wires, motor wires then add 21 pin decoder.  Test.  Solder light wires to small connector board.  Connect small connector board to the Decoder Buddy. Reassemble, run, smile....

Check out http://www.nixtrainz.com Help page for photos of other installation ideas.  Lots of great pictures.

Enjoy!

Nick

Atlas Trainman GP39-2

Although for a GP38-2, this might be helpful:

https://soundtraxx.com/content/Reference/Documentation/Application-Notes/atl_emdgp38-2.pdf

Joe

TCS

This is for the ph. 1 model.

https://tcsdcc.com/installation/ho-scale/634

Ph. 2 model.

https://tcsdcc.com/installation/ho-scale/635

I did not check them for differences.

TCS has quite a site for decoder installs.

Rich

I've got one of these

https://imgur.com/a/RUAEvxP

Frame without the shell, brand new in the box $65.  timagineer@yahoo.com

Go to eBay and check sold

Just go to ebay, type in HO Trainman GP39-2  and the roadname.  When you get those results, go to the top RH corner and click on "advanced" and then click on "sold listing" under the Search Including section.  Then sort the results by "lowest first".  That will give you an indication of value.  Works for anything by the way. 

Craig

Image uploading

Dear WhiteHat,

Just retested, appears working as described...

https://model-railroad-hobbyist.com/help/how-to-post-an-image

Happy Modelling,
Aim to Improve,
Prof Klyzlr

I'm utterly confused by some

I'm utterly confused by some of the responses in this thread.

Decoder buddies are cool, but unless you need a 21pin decoder I'd probably just do as the first response suggested and buy the board replacement version. it takes up less space.

Do note that the Trainman GP39-2 is NOT the same mech as an Atlas Master GP38. I'm not sure on the Trainman GP38. Presumably they are similar. 

Atlas lost the molds to these in the big China kerfuffle that had a few years back, I know they talked about trying to bring them back, but I think they didn't spend the money, because Athearn came out with theirs.

On the other hand…

the Decoder Buddy would be smaller than the replacement board mentioned. It allows for more versatility in installation and if you want more lighting functions to choose a 21-pin decoder would be a better choice.  The wires going to all the extra lights, ie ditch lights, cab light, independent number board lights, beacon or strobe and so on, will all connect through the small connector board and leave the shell separable for other work.  The first picture in the response above shows a Scale Sound Systems speaker that fits into the whole installation nicely.

The picture below shows the three general versions of Atlas frames from oldest in front. 

 

The picture below shows the size of the screw in replacement Decoder Buddy for the top two locomotives in the picture above and the size of the snap in replacement of the bottom locomotive.  Cutting off the clips and mounting the Decoder Buddy with Kapton tape is a good work around shown in the picture in the first response.

The first original Decoder Buddy shown above was a product of not being able to fit a clip model decoder into a QSI and newer Atlas frame.  All the Decoder Buddys are screw in replacements for the current Atlas locomotives.

This is a clip model replacement with Clips removed and Kapton tape.

Next is a QSI replacement.

From the QSI replacement to present are all screw in like the picture above and the standard PNP decoders will not fit without modifying the frame.

On the V5 decoder Buddys two duplicate lighting outputs have been included on the motherboard to allow for ground lights and step lights if necessary.  This allows for the separation of the shell.  The V5B has a pad added to make the third, control,  white wire easily attached to the motherboard.

Hope this helps!

So it turns out, and I did

So it turns out, and I did not know this, the phase 1 and phase 2 models for the GP39-2 have completely different light boards. The phase 1 uses the classic Kato/Atlas style. The Phase 2 is what Nick has described. You should not use the same board for each. Decoder buddy is your best bet in the Phase 2. But I don't agree in the Phase one. I at least prefer the dropins for Kato/Atlas.

The stock board (and a board replacement) is longer, but the decoder buddy, or any 21 pin board for that matter is going to be thicker. Which is the dimension that always causes me the most grief in installs which is why I casually dislike 21pin decoders. I want 1 circuit board period. I find the added fuss and muss of the drop in board to be irksome at a design level (though I appreciate the decoder buddy for what it is. Like that it exists) We aren't talking about complex circuits here. the 21pindecoder is really only of value if you are one who regularly burns out decoders. I have a hard time believing there's a large segment of the model railroad population that upgrades decoders on the regular like they're a car on lease.

AND, they released a Loksound

AND, they released a Loksound version which has a 21pin board in it (though good luck finding the replacement part for it. Looks to be a drop in for the classic lightboard though.

Again, not to discount decoder buddy. (which is available)

I'll add my 2 cents for the

I'll add my 2 cents for the Decoder Buddy. One big advantage is the removal of the lighting board. If you have ditch lights and led's attached to the headlight lens, working on the shell with out the chassis is a major plus. Also the resistors are already there, no guessing. I've done 2 dozen decoder buddy installs from older models (Atlas GP38/40 Athearn Genesis GP's and SD40-2's and Kato units) to ESU 21 pin decoders, and wouldn't use anything else. Double sided foam tape will secure the DB to the top of the motor....