Decoder Install in Bachmann HO Doodlebug

Model Railroader General Discussion (Model Railroader)
1

Repeat posting below, original was inadvertently locked.

I’ve ordered an unpainted Bachmann gas electric “Doodlebug” from my LHS and will be installing a Digitrax decoder. The interior light will be disconnected, the headlight left as is.
Tips and cautions on disassembly, wiring, installation, painting and reassembly welcomed.
Thanks

2

So far no one has responded to the above post, although there have been 33 views. This could mean a number of things-lack of interest/knowledge/experience/no problems etc, or the subject has been lost in the flood of daily posts.

So let’s try again, and add any comments about adding a front end Kadee coupler to replace the dummy one and replacing the boiler tube pilot with a snow plow type.

Thanks to all, even if only for viewing.

3

Sorry. I missed it until now. I am actually very interested, as I am going to build an On30 doodlebug from a Bachmann combine car.

4

Hi Isambard. I just put a decoder in a doodlebug and was glad that I did some research. The plug and play is wired wrong as it comes and need to be modified to keep you decoder from going up in smoke. See http://www.tttrains.com/dcc/dccproblems.htm for the fix. I changed the headlight to an LED while I had it apart. That was a bigger job than I anticipated and took some tearing apart of the radiator and some drilling to get it to fit. Tearing one of these babies apart is a chore the first time. A good manual on this is at http://www.2guyzandsumtrains.com/Content/pa=showpage/pid=20.html .

Have fun, TARP

5

Here’s a link to my topic on soundchipping a doodlebug from a couple of weeks ago - you got more responses than I did - obviously very limited interest.

http://www.trains.com/TRC/CS/forums/859390/ShowPost.aspx

I did manage to get some video of it in action

clip 1

http://www.trainboard.com/railimages/showphoto.php/photo/17846/cat/843

clip 2

http://www.trainboard.com/railimages/showphoto.php/photo/17847/cat/843

Jon

6

Thanks Jon and tooTarp also for the very useful responses. Nice videos Jon.

[:)]

7

As a progress report, the car body and roof are in the workshop for painting, and replacement of the existing headlight with a CalScale Pyle headlight and the rather wimpy bell with a more more robust CalScale one.

I lifted the printed circuit board away from the motor mount without disconnecting the wires and within the narrow space available used the tip of an Xacto knife and a dentist’s pick to cut the copper trace between the soldered bottom ends of pins 3 and 7; using a visor- mounted magnifier to see the trace. The trace was almost invisible due to its tiny length between the “huge” soldered pins and also being covered with semi-transparent conformal coating. I then remounted the PCB and popped a DH123PS into place and did a test run, with very satisfacory results- hooray, the operation was successful!

I’ll post photos on modelrailroadphotos.com as the work progresses further.

[:)]

8

Bachmann may have changed the design of their Doodlebug over the years. I purchased one of the first release and used an NCE plug-n-play decoder that was available at the time. I had no problems at all with anything being wired wrong in this version of the Doodlebug.

9

  1. Digitrax DS123P is what I used, worked fine.

  2. CLIP the orange capacitors, ALL OF THEM.

  3. You can use a Grain-o-rice bulb if you want for the lights

  4. A VERY SMALL screwdriver or BETTER an Xacto #11 blade from the bottom starting at the REAR along the side of the car you can cut away the glue joints and get the whole body off. DO NOT take off the roof, the ^&#^(*&^ never looks good again.

  5. These things run like crap and are noisey till you work on them. Big problem is the gear box is dry (was on both of mine)

  6. When I do the 3td one I will not use a plug and play but hardwire a DZ163 and replace the lighting system so that the interior lights can be turned off ADD marker lights and such.

  7. DO NOT FORGET THE TRACER.

Hope this helps.

10

Hello Isambard!

The youngest member at WIMRC here!

From when I talked to you at LHS, that Doodlebug will look great!

Railfan Alex [8D]

11

What is the Tracer?

12

The problem occurs if there is a decoder function on pin 3. If there is a connection between pin 3 and pin 7 (common (V+), contrary to the NMRA directive, exerising the function will cause a short and damage the decoder. As it happens the DH123PS pin 3 is unused but to be sure I cut the trace.

13

The secret is the rig to hold the doodlebug. I have tried several times to get the shell off with no success. I built a rig like the one shown in the instructions and the shell fell right off!!! Now to order a decoder! I have several Spectrum heavyweights that I hope work the same way???

RMax1

14

The tracer is that little strip under the mother board that connects pins 3 and 7. This is why my 3rd one is being hardwired.

15

You can be absolutly certain the trace is severed by placing an ohm meter across pins 3 and 7. Any thing but a zero reading means more exacto work. TARP

16

Thanks. I forgot to say that I did that before I reinstalled the PCB, using my Sperry multimeter.

[:)]

17

I have a Spectrum Doodlebug that has been laying around for a few years now. Called Loy’s Toys and told them what I have and asked what to do. They sold me a TCS M1 decoder and harness. Installed the things, disabled the rear light and everything is good so far. There will be some minor stuff to take care of but works fine.

RMax1