KB350: Older Proto 2000 Geeps

This article was last updated on Jan. 19, 2012, 12:39 p.m. | Print Article | Leave Feedback

Do you have a reference for wiring Proto 2000 older geeps with a decoder (not necessarily sound)?

We actually have several Life-Like Proto's sitting around for conversion to DCC, including an older GP-18, older FA's and such that date back to the days when DCC was just a twinkle in AJ's eyes.

Overall, converting these locomotives will be fairly easy but there are a few things to watch for.

  • Make sure that the decoder has enough capacity to match the current demands of the locomotive mechanism.  You must measure the stall current of the locomotive to determine this.


  • Make sure that the motor brushes are totally isolated from everything else. If there is an accidental connection from the brushes to ground, the decoder will often burn out.


  • Find a decoder that will fit inside the locomotive.


  • And..... the headlights may need to be replaced.

    For a variety of reasons, Life-Like headlights don't burn at the right brightness.

    There are several Digitrax decoders that are designed to deal with this issue; they will be identified by the "L0" appendix on the decoder name (such as "DH165L0").

    These have current limiting resistors for the forward & rear light functions.

    You can also replace the existing bulbs with 14 volt bulbs.

    This is commonly done with some Proto 1000 locomotives.

That said, hard wiring a decoder into place is just a matter of working deliberately, making each connection properly.

Our decoders use the standard color coding:

- Engineer's side of track pickup from locomotive wheels

- Fireman's side of track pickup from locomotive wheels (or to the metal chassis of some locomotives)

- The "+" side of the motor

- The "-" side of the motor

- Connection for front headlight

- Connection for read headlight

- Common connection for both headlights (each headlight has one connection to the blue wire) Decoders with more functions will have more wires, each for one of the functions.

The instruction sheet that comes with the decoder will have a handy little drawing that details these connections.

It is a little unnerving at first when you have the locomotive open and are cutting wires then soldering their decoder replacements.

So, you may want to start with an inexpensive locomotive first, you know, the one where the decoder is more valuable than the locomotive.

But once you get the hang of it, you will feel comfortable.

A few tips

Once you find a location for the decoder, a small dab of RTV adhesive will hold it in place, letting you concentrate on making the wiring connections.

Also, you will be trimming the decoder wires to length before you solder the connections; you can then use the little cutoffs to tie around the various wires so that all the wires are neat and orderly.

If you find that the forward headlight comes on when the locomotive is going backwards, you can either just swap the orange and gray motor connections or go into the decoder and change the headlight CV's.

Take your time and enjoy the process.

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