Decoder Installation in 

 HO Bachmann F40

by Jim Kirwan

After removing the shell:

If you are not going to use the stock lighting board and are going to use an FX decoder, (you won't need to remove any weight):

01. Remove the 3 small screws that hold the frame halves together.

02. Pull the frame halves apart.

03. Mark the motor so it goes back the same way it came out.

04. Remove the trucks and motor.

05. Remove the light board from the roof of the body and desolder the strobes from it.

06. This step is optional: Remove all of the components from the light board as we will be using it again.

07. Make your light connections to appropriate pads on the light board.

08. Remove the copper contact strips from the motor.

09. Solder the ORANGE wire to the bottom contact on the motor (the arrow on the side of the motor points down).

10. Solder the GREY wire to the top contact on the motor.

11. Cover the contacts with electrical tape to keep the motor isolated.

12. Solder a jumper wire from the from the wiper on the front truck to the wiper on the rear truck on each side.

13. Solder the RED wire to the right front truck wiper. Solder the black wire to the left front truck wiper.

14. Solder the BLUE wire to the appropriate pad on the pc board. The BLUE wire is the POSITIVE for the lighting functions and goes to all of the lights that will be used.

15. Solder the WHITE wire to the pc board for the front headlight.

16. Solder the YELLOW wire to the pc board for the rear headlight.

17. Solder the GREEN wire to the pc board for the left strobe.

18. Solder the VIOLET wire to the pc board for the right strobe.

19. Add appropriate resistors between the blue wire trace and the pads for EACH bulb if you are not using 12-14 volt bulbs. The resistor values can be calculated if you know the voltage and current draw of the bulbs you will be using. Connect resistors to the bulbs.

20. Replace the pc board that was removed in step 05.

21. Use double sided tape to attach the decoder to the light board such that it is above either the front or rear depression in the chassis that was previously used to make room for the capacitors on the light board.

22. Replace the motor in the chassis half.

23. Reinstall the trucks and the white pad below the motor.

24. Put the chassis halves back together.

25. Replace the 3 screws that hold the frame together.

26. Place the loco on a DCC programming track and do what programming you require. This will prevent you from destroying the decoder if you created a short circuit as the programming track is current limited.

27. If all is well, replace the shell and fuel tank and the job is complete.

If you are going to use the stock lighting and are not going to use an FX decoder (you will need to remove part of the weight to make room for the decoder):

01. Remove the 3 small screws that hold the frame halves together.

02. Pull the frame halves apart.

03. Mark the motor so it goes back the same way it came out.

04. Remove the trucks and motor.

05. Remove the copper contact strips from the motor.

06. Solder the ORANGE wire to the bottom contact on the motor (the arrow on the side of the motor points down).

07. Solder the GREY wire to the top contact on the motor.

08. Cover the contacts with electrical tape to keep the motor isolated.

09. Solder a jumper wire from the fromthe wiper on the front truck to the wiper on the rear truck on each side.

10. Solder the RED wire to the right front truck wiper. Solder the black wire to the left front truck wiper.

11. Place the shell upside down. Looking at the upside down shell from the rear, solder the BLUE wire to the LEFT contact strip near the pc board. Cut the contact strip short on the pc board. The BLUE wire is the POSITIVE for the lighting functions and goes to all of the lights that will be used.

12. If you want the headlight and strobes on when the unit goes forward only: Solder the WHITE wire to the RIGHT contact strip near the pc board.

13. If you want the headlight and strobes on when the unit goes forward or reverse: Solder the WHITE and YELLOW wires to the RIGHT contact strip near the pc board.

14. Cut the contact strip short.

15. Cover the remaining contact strips with electrical tape.

16. Cut off some of the weight near the rear of the frame halves to make room for the decoder you will use. Do not remove the material where the screw goes between frame halves. Clean the frame halves.

17. Replace the motor in the chassis half.

18. Reinstall the trucks and the white pad below the motor.

19. Put the chassis halves back together.

20. Replace the 3 screws that hold the frame together.

21. Use double sided tape to attach the decoder to the frame.

22. Place the loco on a DCC programming track and do what programming you require. This will prevent you from destroying the decoder if you created a short circuit as the programming track is current limited.

23. If all is well, replace the shell and fuel tank and the job is complete.