GP7 taking off shell

[Tomie]

How do you remove the shell off a GP7?  SoundTraxx says that a Tsunami 828040 decoder along with a 810113 speaker is required for this engine.  Someone in another thread said that the chassis was already milled out for a speaker.  I would like to see if that is true.

Tom

[jward]

you don't have to take the shell off. just remove the fuel tank cover and you'll see the opening. the bottom of the fuel tank cover also has holes drilled in it for a speaker.

[richg]

Take a single layer of coffee filter material and cut it to fit the speaker area. The magnet in the speaker will pick up magnetic particles in the roadbed. This has happened to some.

Rich

[Tomie]

The 810113 speaker is oval while the speaker in the fuel tank is round.  I don't think that SoundTraxx  would recommend a oval speaker to go in a round hole.  There must be something on the chassis to hole the 810113 speaker.

Tom

[richg]

Many HO scale locos use a 28mm round speaker. Looking at the diagram page, it does appear that 28mm would fit. SoundTraxx sells that size also. I bought them.
I have bought most of my DCC stuff from Litchfield Station.

Rich

[richg]

I did a little searching and someone mentioned they used a 3/4 inch speaker and sealed the rear of the speaker cavity to make a baffle.

GP7 parts in the below link.

http://estore.bachmanntrains.com/index.php?main_page=index&cPath=66_68_188

Rich

[Tomie]

I found a post on taking off a GP40 shell that says to remove the fuel tank and take out 4 screws then remove the shell.  Does anyone know in the GP7 is the same?
Tom

[richg]

Yeah, Just realized no one said how to remove the shell. Have to, to install a sound decoder and connect the wires to the speaker in the oil tank.
I have no idea as I do not have the loco but I believe you have to start with removing the couplers from a post I saw some months ago. Cannot find the message right now.

Rich

[Tomie]

Just finished installing a Tsunami TSU-AT1000 digital sound decoder in my GP7.  Taking the shell off was easy, just remove the screws from the couplers and the shell comes right off.  Most of the wiring was simple.  The circuit board is wired using retainer clips so when you take them off the wires come off.  Putting the ASU-AT1000 board in was simple using the retaining clips to hold the wires.  The headlight output is 12 volts so you need two 680 ohm resisters placed in series with the LEDs.  The speaker takes two 28 gauge wires and one of the LEDs has leads that needs to be unsolder-ed.  That is about it.  Now my GP7 has a EMD 567 motor sound and the control is better. 

Tom