Hello Everyone--

Embarrassing as one of these questions is, l rather ask than damage a new analog SD40-2 loco.  First, what's the best way to remove the shell with damaging it or the chassis? The exploded diagram isn't helpful.  Second, can I install a decoder by simply replacing the circuit board with an after-market "Bachmann Replacement" decoder?  OR must I hardwire one?

Thanks,

Steve

Steve,

Usually, Bachmann diesels are set up so you must remove the fuel tank to access the two screws that hold the shell to the frame.

Looking underneath, you should see a tab on either side of the tank.  Some can use a small screwdriver or toothpicks to release these tabs.  I've known some who could squeeze the tank in such a way as to release the tank.

Once the tank is removed, you should see 2 chrome-plated screwheads (Phillips).  Removing these screws should allow you to safely remove the shell.  The newer Bachmann models do not require you to remove the couplers.  Check, just in case.

Once the shell is off, you should see the light board sitting on top of the frame.  If the loco is DCC ready you will see some sort of receptacle with dummy plugs to accept a Bachmann-type decoder.  If you don't see this, a decoder with have to be hardwired.

According to the diagram, there is already a recess in the frame to accept a small decoder, without having to mill out a space.

I haven't opened up one of my diesels in a long time, so take these words with a grain of salt.

Regards,

Jonathan

Addendum:
Nothing embarrassing about questions, my friend.  This is how we learn. Lord knows I've asked a ton myself.

The last time I looked at the NCE site, they show the manual for the Bach DSL decoder, specifically made for the Bachmann diesels. Download it to your PC.

Rich

A couple of points I'd consider before I started cutting wires and getting the soldering iron up to temperature.
1 - Take a postage scale and weigh the locomotive, if it does not weight more than 14-15 OZ, the pulling power will be less than what I require.
2 - Check to see if the locomotive has flywheels on the motor shaft. Flywheels are typically brass/copper color and at least 1/2 inch in diameter.

Without the two conditions both being in the affirmative, I would not spend the time and money on the locomotive. 

I've a set of F7's that I tried to dcc sound equip and found the results to be well below my standards.

Here is a link to some of the differences I encountered in my F7 adventures.

http://joe-daddy.com/index.php/the-train-room-2/138-bachmann-f7-locomotive-internal-differences

Joe