# Need Help on decoder install on a bachmann SD 40-2



## HOMODELTRAINZ2009

Hey guys I desperately need help on installing a digitrax sdh164d with a SoundTraxx 810113 Oval Speaker in my bachmann sd 40-2. I attached pictures with the shell off to show you what the inside looks like. I have a basic knowledge of how to wire it but I'm not sure how everything is going to fit inside. I sure appreciate any help.

Thanks, Josh


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## TONOFFUN80

You may have to remove some of the weight to make room for 
your speaker


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## gc53dfgc

yeah, you will have no choice but to remove weight to have room. I had to do it for my sd-40-2 which I started the install guide for but need to fix some ditch lights before it will be all uploaded.


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## HOMODELTRAINZ2009

gc53dfgc said:


> yeah, you will have no choice but to remove weight to have room. I had to do it for my sd-40-2 which I started the install guide for but need to fix some ditch lights before it will be all uploaded.


Yeah Gc, if you would post it soon I would definitely appreciate it if you can


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## NIMT

Another option is to install the speaker in the fan on the top.
I do that all the time!
I wouldn't use a Digitrax SDH164D with a SoundTraxx 810113 Oval Speaker, it's too large. 
I would use a Tsunami TSU-750 or 1000, or a Digitrax SDN144 and a small round speaker that fits the fan hole. if you really want to pump it up put in a pair of speakers in the two center fan holes!


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## gc53dfgc

Sean you are right and that works with all of the other brands that either have see through fans or space, but the Bachmann SD40-2's have just all plastic fans that let nothing out and there is literally no space from the top of the shell to that circuit board. It is nothing but weight all around and the only way to fit anything larger than the original board or DCC equivalent is to cut into. Believe me I tried everything to get the smallest speaker and decoder (Soundtraxx) and it still required cutting. Bachmann just never built there units with the plans for DCC or DCC/Sound to be added in later. In fact i actually replaced those all plastic fans with the see through type for more room and better sound output from the engine.

Modeltrain,

i will see if I can get the last part I need from my hobby store tomorrow and then get the last of it updated.


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## HOMODELTRAINZ2009

gc53dfgc said:


> Modeltrain,
> 
> i will see if I can get the last part I need from my hobby store tomorrow and then get the last of it updated.


Ok awesome thanks, Yeah I looked at putting speakers where the fans are at but your right Gc there is no room at all.


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## HOMODELTRAINZ2009

Hey guys I received my digitrax sound decoder dh164d today along with my soundtraxx speaker. With my dads help at his shop he was able to mill a couple sections down on the frame for the decoder and speaker to fit in perfectly. Now I have to wire up the decoder and speaker hopefully that will go ok its my first one. I will post several pic's to show the process of it being completed. Let me know what you guys think when I get the pic's posted.


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## Artieiii

Josh, new speaker could be problematic on the SDH164D. They come with 32 ohm speakers and nobody makes replacement speaker like that (that I could find). Almost all aftermarket speakers are of the 8 ohm variety. If you put an 8 ohm speaker on the decoder it could easily blow out it's circuitry (too little resistance). It is my understanding that adding a resistor is not a recommended practice either. Sticking with the digitrax attached speaker is the only viable option.
-Art


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## HOMODELTRAINZ2009

Yeah I was worried about that too but my friend has changed several of them to that speaker and so far no problems as of yet and they are ran for several hours a night.


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## HOMODELTRAINZ2009

Also I just checked the decoder paperwork and it said you could replace the speaker with an 8ohm or greater speaker. So hopefully I wont have any problems with it.


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## mr_x_ite_ment

I wonder if it is possible to find a spot for the decoder in the cab area, where the top part of the heavy frame drops down near the light? Obviously I am talking about a decoder that is not a PCB board. I know that the decoder/wires might show in the window of the cab, but I don't think that would bother me that much. Does anyone have any thoughts on that? I am looking at replacing a Bachmann decoder or two.

Chad


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## gc53dfgc

That is a no can do for the most part. You have to have someplace for the resistor which happens to be where I shoved it and there is little space, I also got the last of the parts I need to finish the engine so I should be done with it on Monday and have it up here by Tuesday since Christmas Break is finally here, Aaaah FREEDOM!


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## mr_x_ite_ment

Hey gc...I just went out and looked at mine (the Bachmann I want to switch decoders on). It is a GP-50, with the high hood, so there is even LESS room under the shell. I am wondering if I should replace my decoder with the NCE drop-in replacement pcb board. I believe they call it the NCE Bach-DSL decoder. At least I know this would fit under the shell. Do you, or anyone else, know how well the NCE decoder works in the Bachmann standard line?

Chad


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## HOMODELTRAINZ2009

I have another question can I replace the incandescent bulbs with L.E.D.S.? I have 3mm led’s with resistors that will fit on the loco. Will that hurt the decoder if I switch to led’s?


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## NIMT

Yep they will work out great, LED's pull less amps than Lamps and with less heat too!


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## HOMODELTRAINZ2009

NIMT said:


> Yep they will work out great, LED's pull less amps than Lamps and with less heat too!


Thanks Sean!!


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## gc53dfgc

HOMODEL,

You will also need to make sure there are resistors in the proper places for the LED's otherwise they will blow every time. 

mr x,

If you are not planning on putting sound into your engine and just want DCC the best option would be to get the drop in decoder that replaces the old PCB. NCE makes good decoders as does Digitrax so just finding the right one for your engine and going with it is about all you need to do. Just read all of the dimensions of the decoders and then compare to your engine.


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## mr_x_ite_ment

gc...Yea, I think I will maybe just get the NCE drop-in replacement for the PCB. I like the way you ground out a spot for the DH123D in that Bachmann GP-38 you did. I am not opposed to grinding out a spot either, but for the same price I figure I might as well get the drop-in replacement, and save myself some grinding. Thanks for the input!

Chad


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## HOMODELTRAINZ2009

gc53dfgc said:


> HOMODEL,
> 
> You will also need to make sure there are resistors in the proper places for the LED's otherwise they will blow every time.


Gc,

Do I put the resistors on the positive end of the led?


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## gc53dfgc

If I had had more time and thought more about it I most likely would have just gotten a drop in, but that engine is the first one I got and about the worst runner(though I still like it) so I decided to experiment on DCC install tricks and that was one. I am glad I decided to try it on that engine though as the SD40-2 was getting sound and no space at all so that became the only option, that way I already had some experience.


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## gc53dfgc

HOMODELTRAINZ2009 said:


> Gc,
> 
> Do I put the resistors on the positive end of the led?


Yes, all LED's have one lead that is longer than the other and this lead is where the resistor is soldered onto. Now some people go right off the common wire of the decoder but that means if one LED goes out the other will also so just putting one resistor per LED is best. Also make sure to get Warm/yellowglow LED's which give off a more incandescent light over the blueish color of a regular white LED.


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## HOMODELTRAINZ2009

Thanks Gc!!


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## NIMT

GC, Where is the proper place???? Not on the floor or work bench I would say!:laugh::laugh::laugh:
The resister can go on either lead of the LED just make sure you use one 470ohm resister per LED.
I think I know what GC was trying to get at was to not use one resistor to power several lights! I make a habit of installing the resistors on the - side that way I connect up all the + commons and run them back on one wire. IE, strobe # boards, Head lights, red light and ditch lights all only need one common. otherwise you would need 7 more blue wires + Common and -hot wire per LED.


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## HOMODELTRAINZ2009

I finally got the decoder installed late last night after lots and lots of grinding :thumbsdown:. Soldering the wires and installing the new leds went very well. The only main issue was all the grinding that had to be done for the speaker and decoder to fit properly with the shell on. Here are some pictures of what the process looked like sorry the pictures are not the best quality, I guess that's what I get for staying up until 4 in the morning to finish, just to run my train with sound lol. Thanks guys for all your help on answering my questions!

After all the Grinding


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## mr_x_ite_ment

Josh...looks like a nice job of grinding and installing to me! I need to work on a Bachmann or two myself. I think I will try a new pcb board from NCE so that there will be room for it without any grinding. I wish Bachmann didn't have the upper half frame...it doesn't leave any room to work under there! Nice job!

Chad


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## HOMODELTRAINZ2009

mr_x_ite_ment said:


> Josh...looks like a nice job of grinding and installing to me! I need to work on a Bachmann or two myself. I think I will try a new pcb board from NCE so that there will be room for it without any grinding. I wish Bachmann didn't have the upper half frame...it doesn't leave any room to work under there! Nice job!
> 
> Chad


Thanks Chad,

Yeah it took a couple hours of grinding to make it fit.


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## gc53dfgc

It looks pretty good Josh, How exactly did you do all of the grinding on the engine? On my engine i used a round circular cutter and made a more box type cut. The disk was a metal and mesh round cutting disk meant for steel or stone. 

Are you planning on adding ditch lights to your engine? That is the only thing keeping mine from being done which was supposed to be yesterday but family and Christmas things got in the way, I am hoping to get it done tomorrow so if you are still interested in pictures of mine I would be more than happy to post them on here.


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## HOMODELTRAINZ2009

gc53dfgc said:


> It looks pretty good Josh, How exactly did you do all of the grinding on the engine? On my engine i used a round circular cutter and made a more box type cut. The disk was a metal and mesh round cutting disk meant for steel or stone.
> 
> Are you planning on adding ditch lights to your engine? That is the only thing keeping mine from being done which was supposed to be yesterday but family and Christmas things got in the way, I am hoping to get it done tomorrow so if you are still interested in pictures of mine I would be more than happy to post them on here.


Thanks, Gc

Definitely I would like to see the pics of you installing your decoder. I never turn down pics of train’s lol. I used a cutoff wheel and several other odds and ends not sure exactly what there called I would have to ask my dad. I would love to add ditch lights to mine also but not sure if I have the skill to do it and not even sure where to begin to start with that project.


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## Cab1

Man, you think you had trouble? I have an HO Bachmann Spectrum GE DASH 8-40C. This thing is strictly DC and Bachmann didn't even leave a whisker of extra room for anything. The shell fits tight around a split frame that has plastic insulators between the two half's - one side is positive the other negative. Even the lights are not lights. It has an elaborate clear plastic reflector up front in the cab and another one in the back that can't be removed - if you want lights. Two small bulbs encased tightly in blacked out tubes direct light at the reflectors. Hey, it works. Somehow the light snakes its way through the twists and turns of the reflector and pops out a lens right where it suppose to be. I can't really change any of that, but I will replace the bulbs with bright LEDs and rip out the light board - which no longer serves any purpose. I'm using a Digitrax SDN144PS decoder and will replace the speaker with an 8 ohm Soundtraxx 0.91 square mega brass speaker. That's the hard part - the speaker. There's just no room. I thought about putting it in the fuel tank, but the tank fits tight against the frame. So I have no choice but to cut out a notch in the bottom of the frame big enough to fit the speaker. Then it can be covered by the fuel tank. I'll upload some pictures when I get a chance. Wish me luck.


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## NIMT

Cab1,
I would be cautious on installing the Digitrax SDN144PS decoder with the Soundtraxx 0.91 square mega bass speaker! I'm not sure the amp on the 144 can handle driving such a big speaker, and if it does I'm not sure how long it will do it for.
It's like putting a V8 in a go cart frame, somethings got to give.


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## shaygetz

HOMODELTRAINZ2009 said:


> I used a cutoff wheel and several other odds and ends....


Cool...I was thinkin' that you just reared up and bit a chunk out....:thumbsup:


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## Cab1

The Digitrax SDN144PS decoder already comes with an 8 ohm speaker - a tiny one. I figure 8 ohms is 8 ohms. I've tested it and the larger speaker area puts out much better sound. Besides, I broke the wire on the teeny little thing and there's no way I can fix it. We're in the deep water now. Anyway, you're right it's only a 1 Amp decoder, so we'll see over the long run. More important is the motor amp draw. Since I'm gonna toss out the bulbs for LEDs that will help out a tad. It's a relatively new loco with a solid motor with two big brass flywheels. It really pulls. That's why I even bothered going DCC with it. I got it new in the box off ebay. Here are a few pictures. They're not the greatest, but here goes.


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## Cab1

The pictures didn't go through. It's asking for a token. What did I do wrong? I'll try again later.


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## Massey

Best to use Photobucket and then just copy and paste the [img ] tag to the forums.

Massey


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## NIMT

Cab1,
Yes it's 8 ohms, but the little speaker is only .1 watt and the new speaker is 2 watts...huge difference on the amplifier demand.
The 1 amp rating is not for sound it's for stall current on the motor.
They don't give the power that the amplifier puts out.
That all said if it works great but if you loose sound you'll probably know why!


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## Cab1

OK, here is another stab at uploading the pictures.

http://s1209.photobucket.com/albums/cc387/Cab1Train/

I know, they're terrible. I apologize in advance. I didn't mean to hijack the thread either.


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