Morning all,
So I mentioned a few times in the past where I had bought a lot of model trains on an online auction on eBay, and I want to add sound to the units. I’ve been talking to @AVTrainz about it, both units run really well, but here’s what they look like right now (I’m sorry about the poor lighting 
)
I have the units numbered as the following:
IACR EMD GP40M-3 #4 Ex. NCRX EMD GP40M-2 #4 Exx. SOO LINE EMD GP40-2 #4842 (Red front, black nose)
IACR EMD GP40M-3 #7 Ex. NCRX EMD GP40M-2 #7 Exx. BNSF EMD GP40-2 #3007 (all black body, damaged)
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I’ve never installed sound on a Bachmann locomotive, I usually do it to Athearn Blue Box locomotives 
, I wish I could help you @GabeTehGameh!
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Hey Gabe, after looking at the photos, the first thing I see is that the control board would need to come out, leaving only the motor and light wires behind to connect to a decoder. What is going to be a really big obstacle is the upper half of the frame. Since that takes up all ths space between the drivetrain and the roof of the shell, there’s no room for speakers. Are any parts mounted to, supported by, or held down by it? It would definitely need to be removed but if for example it functions as the motor clamp that’s going to make things way more difficult. If it can’t be removed, the harder option would be to grind a deep notch at the rear under where the loco’s radiators are to allow the speakers to fit. From the photos it doesn’t look structurally important but I’m not sure.
Hope this helps.
There’s screw holes in the front and back of the unit (can be seen in the photos) if I remove them and use a Dremel to shorten it or get a smaller metal internal frame that should leave room for speakers but yeah I could always turn the radiator fans into spots for the speaker(s) but do I need any specific parts?
Not necessarily. If you can just take that upper frame right off, all you need to do is mount the decoder above the motor, and mount the speakers underneath the radiators in the shell.
Can’t he adapt the connector for lights in the ‘front’ to LEDs in appropriate places in the shell, and then Dremel out room for one of those speakers that installs in the ‘cab roof’?
That’s what I was thinking about doing
Hello All,
To clarify- -the upper section of the frame is the point where the gear towers are attached.
If you, “…just take that upper frame right off…” there is no place to mount the gear towers.
I have installed Digitrax, non-sound decoders, in my all my Bachmann GP-40s.
You will need to remove the Original Equipment Manufactured (OEM) Printed Circuit Board (PCB) and hard-wire the new harness to the track pickups, motor connections and lighting outputs.
The number of supported lighting outputs is determined by the series of decoders used.
Some decoders support only two (2) lighting outputs while others support many more.
While doing this conversion, I recommend upgrading to LED lighting.
As far as speaker placement- -unless you can mill out a channel in the existing frame weights- -your best bet is to mount it in the fuel tank.
You can drill holes in the fuel tank cover to allow the sound to emanate.
Hope this helps.
Yeah, that’s what I was asking in my earlier post. I could not see whether the upper frame provided any support for anything mechanical. (First post) “Are any parts mounted to, supported by, or held down by it?” Since the gear towers are mounted to it he will indeed need to grind a notch or channel in the upper frame underneath where the radiators are of he plans to put speakers there.
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