I converted the Doodlebug to DCC using an idea seen on a web site that's now gone. The idea was to place the decoder under the frame of the locomotive in plain view. Eventually we will make it look like a baggage compartment. So, I first took a "before" photograph.



Taking the body off was actually quite difficult. The above-mentioned web site says that there are three tabs, however my model only had two tabs. I tried inserting toothpicks and jeweler's screwdrivers to separate the body from the frame, but I had no luck. A certain amount of brute force was needed. I think the key is to know where the tabs are. I have indicated them on the photo below. In the process of removing the body I wound up breaking one of the body's inserts. Luckily all the broken parts stayed in the cab and I was able to glue them back together. My advice is to do all the interior work you want to do once you get the body off, because you don't want to go through that agony again. We intend to replace the LED with a bright white LED and to glue in some passengers in the interior.



After the shell came off the front weight (shown on the left in the next picture) fell out. We need to remove the light board, so loosen the wires (as indicated) with a soldering iron.



Once the wires are loose, remove the light board by removing the two screws holding it down to the frame.



In the next photo you can see the light board removed. The next step is to remove the motor from the frame. You'll notice two screws on the underside of the frame. Unscrew the motor.



After I removed the screws the motor didn't fall out. As a matter of fact, I think it was glued in place. I was able to pry a jeweler's screwdriver under one side of the motor between it and the frame, but the other side wouldn't budge.



Again, a careful application of brute force broke it loose from the frame (no damage, though, this time).



The next step is to drill some holes in the frame. I marked the frame where I want to drill. The red lines point to the locations.



Before I could drill the holes I first had to remove the cabin seats. Just like all the other parts, this took some time because the plastic piece did not want to come loose from the frame.



Here is the frame with the three new holes drilled in it. I first drilled the holes with a 1/16" drill and then widen them with the 3/32" drill bit.



At first I couldn't figure out why the instructions said to drill 3/32" holes because they seemed too large for the wires. However, as you can see from the photograph below, the idea is to put some shrinkable tubing in the holes which prevents shaffing of the wires during operation. Clever. I used Radio Shack's shrink tubing. The white tube was the smallest with the largest inner diameter.



So, all the holes are filled with the tubing and so we are done with the frame modifications. I used super glue to hold the tube pieces in place.



The next photograph shows the decoder with all of its wires routed through their appropriate holes. I temporarily taped the decoder to the frame with electrical tape. However, eventhough the instructions tell you to route all the wires through their respective holes, don't do the orange and gray wires yet (the ones in the center hole).



With the motor temporarily put back in its place on the frame, mark the bottom of the motor through the center hole. The next step is to drill a hole in the the motor casing so that the two wires can be routed through that hole. This is very dangerous work. One slip (drill too deep) and the motor is history! I used a small pin vise and then followed it up with the 1/16" pin vise for the final shape. This gave me maximum control. It took a lot longer than drilling the hole with an electric drill, but at least I still have a motor to run with :-)



The next photo shows the motor in place and the orange and gray wires fed through the frame and motor hole and routed betwen the motor casing the brush holders.



The next step is to make modifications to the light board (through which the track feed power routing is done), but I wanted to first replace the yellow LED with the new white LED. I left the original resistor in there (270 ohms). After replacing the LED I made the cuts in the circuit board using a utility knife (indicated by the red lines). At this time, also cut the rear lead of the resistor off (or unsolder it and bend it out of the circuit board). This was not mentioned in the instructions on the other web site until much later. The resistor's leads are so close to the circuit board that the metal cutter I was using almost wasn't able to reach the resistor's leads.





Now comes the fun part - attaching all them dar wires to the locomotive. First up is the red wire. The above-mentioned web site describes what to do with the red wires, but I couldn't figure it out. After spending some time studying it, the picture below shows my interpretation. Basically the red wire needs to be soldered to the piece of the circuit board that was completely isolated by the two cuts we made earlier.



The insulation paper needs to be cut a little. The instructions say to glue the red, white, and blue wires to the inside of the frame by the front truck. These wires now no longer allow the paper to fit in its position, so one side has to be trimmed a little. By the way, the hole in the paper matches the pin near the front of the locomotive's frame.



Now the blue and white wires are soldered to the LED and the resistor, respectively. Note here the cut resistor lead mentioned above. Bend it out of the way so that it doesn't make contact with it original position.



And, finally, solder the orange and gray wires to the top of the circuit board near the rear end of the board.



Solder all three of the remaining black wires together. They will eventually be placed under the cabin seats, but for now they are visible. I did cover the solder joint with electrical tape to prevent shorts.



Here is the final beast. At first it didn't do anything when I set it on the track. I eventually got the LED to briefly blink. After squeezing, pushing, prodding the locomotive it did finally move. It turned out that I needed to shim up the motor casing a bit to get the motor's brushes and the circuit board to make contact. Also, the locomotive hadn't been driven in a while, so it was a bit sluggish.



This blurred image is the locomotive blasting by the camera. The LED works great. I let the locomotive run around our mainline loop for a while to warm it up. The first two loops around required the occasional push, but once it was warmed up it did OK. This locomotive is not a Kato or Atlas, so its performance is not stellar to begin with. I needed to set the Digitrax throttle to 55 to get it to move at a decent speed. One nagging thought I have is that the motor or the gearing mechanism is rubbing against something. After running a number of loops, the motor was hot to the touch - not a good sign (but can that be due to the cheapness of Bachmann products?). Anyway, a Doodlebug is used for short local hauls, so it wouldn't be driving for hours at a time...