Dc gp40-2

[trainboy6936]

I currently have two dc gp40-2,s. And recently have added dcc to my layout. What I am wanting to know is how do you convert these locomotives to dcc ? Thanks for any help I get.

[blwfish]

I don't know how old yours are, but if they're reasonably recent (past ten years or so?) they should have what's called an NMRA 8-pin socket inside. A DC loco these days has a dummy plug in that socket, and it is a very simple matter to pull it out and plug in a DCC decoder. As long as you're just going for DCC, a "fleet" decoder is a small item that shouldn't be too difficult to place in the loco. I've done a couple diesels in that general way, and that works pretty well and is pretty easy. At least one of them was a mere 5 minutes after the shell was off. Of course, you still have to program the DCC, but that's true of pretty much any DCC decoder.

If you want sound, that could be a much more elaborate effort. Some of Bachmann's diesels often are pretty full, and finding space for a larger decoder (the sound decoders are probably 3x the size of the simpler DCC-only ones), a speaker, and some other wires can be something of a trick and might be a pretty fair undertaking, although there's no rocket science involved.

There's also a big difference in price: a regular decoder costs about $20 and if bought in quantity (as some clubs do) can be had for as little as $12-$15. Nearly all sound decoders run $80+ and usually that also doesn't include a speaker (another $10+).

[trainboy6936]

Mine are less than 10 yrs.

[richg]

Mine are less than 10 yrs.

It is always advisable to remove the loco shell and see what is inside. You are going to have to open the loco anyway. Sometimes posting a photo using Photo Bucket is very helpful.
The are a variety of decoders made that will work. Digitrax and TCS make some nice small decoders.
Below is only one example of a plug in decoder on a Bachmann loco.

http://www.tcsdcc.com/public_html/Customer_Content/Installation_Pictures/HO_Scale/Bachmann/Spectrum_SD45/bachman_spectrum_sd45.htm

If all you see is a PC board with no plug, you will have to hardwire.  NCE makes a very good PC board type decoder made specifically for the Bachmann diesels that have no way of attaching a decoder. It comes with instructions. Replaces the stock PC board.

Rich

[trainboy6936]

So I got the shell of today and there is no room for a decoder. So now what???

[jward]

there is room for a decoder, but you'll have to hard wire it. nce makes a replacement board specifically for Bachmann diesels, it replaces the pc board already in the gp40.

this is not a particularly difficult conversion, but you should at least know how a model locomotive works before you attempt this. you will have to isolate the motor contacts from the chassis among other things.

[richg]

Is the below diagram what you have? A diagram or photo can make it easier to understand, isolating a motor than just a sentence.

http://www.hoseeker.net/assemblyexplosionbachmann/bachmannemdgp40pg02.jpg

If it is, the motor is isolated from the frame.
Look at the two motor terminals. Do they have wires to the truck pickups or do the two motor terminals connected to the loco frame halves?
Is there a PC board like the diagram link I posted?
Older Bachmann locos used the frame halves for bringing power to the motor.
That is why a photo can help. Make it a point to get a Photo Bucket account for posting photos. It will reduce frustration and make it easier to solve issues with trains. Some here refuse to do that and it can take a lot of messages and time to solve issues.

Rich

[trainboy6936]

Yes that is the exact type of loco I have.

[richg]

Yes that is the exact type of loco I have.

I cannot see exactly what the frame and wiring looks like but that diagram tells me the motor is isolated and not connected to the frame.
If you ever tell someone to make sure the motor is isolated, put in your message some details of exactly what that means.
Many times a visual inspection of the loco is required and a few locos, you actually need to use an ohm meter because some brands of locos, the motor frame halves are electrical part of the brushes. I have a Walther's loco that is like that.

The below decoder is specifically designed for Bachmann most diesels.


http://www.ncedcc.com/pdf/BachDv35.pdf

It comes with instructions and don't throw the instructions away after. Some clueless here do that and we hear whining about no instructions. Sigh.
Good luck. Take your time. This is model railroading not playing with trains.

Rich

[trainboy6936]

Now will this decoder work in a ho diesel?

[richg]

Now will this decoder work in a ho diesel?

Sigh.

Go back and read the PDF. That is exactly what this decoder is for.

Rich

[trainboy6936]

Oops.  I think I read right over that. And to..make sure . This   decoder will be able to replace the dc pcb board?

[jward]

yes it will replace the dc pcb.

and for rich, the current incarnation of gp40s appear to be have the motor isolated, but there are previous incarnations out there that do not. it all depends on how old the locomotive is. there are plenty of older models out there in the shops or online.

[trainboy6936]

Got the unit converted yesterday. Runs like a charm. Thanks to everybody who has helped me. Thanks. Now to figure out the sound part?