There are already a couple of decoder installation guides for the LifeLike SW9/1200 (actually supposed to be an NW2 if it's in Chessie colours) available on the internet (details at the end of this page), but they both involve frame modification to make the decoder fit. This guide involves absolutely no frame modification and only minor surgery to the locomotive's light board.
Incredible as it may seem given the small size of the locomotive, this is really the easiest decoder install I've ever done. I used the Lenz LE0521W (Old LE010XF) decoder, since it's small enough to fit inside the little switcher's cab, which makes frame milling to make room for the decoder unnecessary.
Remove the cab and fuel tank according to the instructions in the loco's handling notes. It helps to carefully slip a knife blade in between the bottoms of the cab sides and the sill, to get the clips to release. Then press down on the exposed part of the frame where the cab had been, and slip the rest of the shell off.
Throughout the task, keep in mind that the four little brass wipers that are fitted on the four corners of the bottom of the shell to act as bridges between the truck wipers and the frame can get damaged easily, and can also come loose easily. They are difficult to replace once they have broken out of the little plastic protrusions in the shell which have been melted down to keep them in place. Been there, done that! In the end I resorted to a spot of super glue, which did the trick.
Remove the trucks. If you turn a truck through 90 degrees, it will just fall out of the frame. Next remove the little round covers from the frame's screw heads by slipping a thin jeweller's screwdriver under them and popping them out, undo the screws and take the frame apart. (You have to replace these covers in the end or the screw head recesses can damage the shell wipers when you replace/remove the shell again.) Take note of which side of the motor is supposed to be at the top - I suggest you mark the top with a permanent marker before proceeding. Remove the motor from the frame, then slip the motor out of its saddle.
To isolate the motor, just slide off the two wipers from the brush caps and discard them in the spare parts bin.
I'm not giving any wire lengths here, since I did not make notes of the lengths. It is easy, however, to estimate the grey wire length by fitting the motor back into one frame half and tracing the wire route all the way to the cab, with about an inch for slack. On almost all the wires I had to cut off only about ½ to 1 inch to get the wire to the correct length. Start with the grey wire first, by soldering it to the bottom brush cap.
Unless you're comfortable with soldering directly to the brush cap while it is still fitted to the motor, rather remove it before soldering, and replace the brush cap afterwards. Melting the plastic of the motor where the brush cap fits into is a BAD thing. Losing brushes and brush springs while removing the brush caps is also a bad thing, so be careful! Then refit the motor in it's saddle with the grey wire threaded up in a little gap between the motor and the saddle.
Reassemble the frame halves with the motor in place, but don't tighten the screws yet since there's still some work to do on the light board. Then solder the orange wire to the top brush cap.
I used the light board for power pickup. Cut the trace to the LED's right leg - just a brief touch with a Dremel's cutting disk will do it - and unsolder the end of the resistor that's not connected to the left leg of the LED.
Solder the blue wire to the right leg of the LED, white and yellow wires both to the free end of the resistor (or just leave the yellow unused, or use it to install an LED in the cab - there should be enough room). Solder the black wire to the left pad, and the red wire to the right pad.
Once you've done soldering and fiddling with the light board, tighten the frame screws and replace the screw caps. It's also a good idea to place a piece of insulation between the light board and the end of the resistor where the white and yellow wires are attached.
I discarded the cab weight to make room for the decoder, but I plan to cut off the weight's "legs" some day and use them inside the cab sides where they belong, like saddle-bags or motorbike panniers. To prevent wires from touching the rear worm and the flywheel, I cut a small piece of thin plastic to cover the cavity over the worm, with one end of the plastic held in place by the top brush cap's groove.
Then thread the decoder through the cab hole in the shell and replace the trucks and shell - see the picture, showing the wires neatly in place so as not to obstruct anything, and with the plastic cover in place above the worm and flywheel cavity.
Before replacing the cab, first do a final test for shorts, and then you can program the decoder.
After programming the decoder and a test run, you can replace the cab. Since the wires and decoder will be visible through the windows, I put some black tape on the inside of the windows. Slip the decoder into the cab. It is small enough to go almost to the top of the cab. Make sure the wires are in the centre of the gap in the frame so they won't interfere with the cab or the shell's fit on the frame, and replace the cab, allowing the wire slack to settle into the cab in a zig-zag fashion. And you're all done!
Some people have reported problems with traction loss, gear noise and even tail-high locos when installing the decoder in the cab of the SW9 by removing the weight, the way I described it here. I have done three of these locos, and yes, you do lose some traction. This doesn't bother me much since my yards are on the level and besides, since I have three of these locos I can just MU them together if the job requires more traction.
I did NOT experience any gear meshing problems, or tail-high locos, or power pickup loss, or any other kind of problems - in fact these locos are the most surefooted of all my locos (some Katos, several Atlases and more LifeLikes) over even the most difficult and crappy yard tracks at crawling speed. They don't even stall on the plastic frogs of Peco insulfrog turnouts.
Maybe I was just lucky..... But consider this: The way I did it involved NO modification to the loco at all except for a scratch on the light board, and takes less than an hour to do. On the decoder, on all seven wires the longest piece I had to cut off was about an inch, so all decoder wires are still almost intact after installation. Therefore, if you do it this way and you do have gear meshing hassles or any of the other reported problems afterwards, since the loco is still unmodified it's still possible to just replace the cab weight, and then try another more drastic installation method that may involve frame milling. But once the frame is modified there's no going back.
There are two such installation guides available where frame modification is involved that I'm aware of. The first is by Professor Stefano Curtarolo and the second by Joe Ellis.
If anything about the procedure is perhaps still unclear, or if you used this guide and it worked for you, please drop me a note.
Good luck, and keep them on track!
The following pages contain decoder installation guides for some other N scale diesel locomotives:
And the following pages contain guides to servicing or performance enhancement of some N Scale diesel locomotives:
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Created in February 2002. Last updated on 11 September 2003.