More On Atlas FP7 DCC Conversions

One thing I've discovered about vintage locos without DCC sockets is that there are often no single ways to convert, and none of them is quite perfect. My first couple of FP7 conversions on the 1990s Roco version involved cutting the traces on the PC board and soldering the truck and headlight leads from the chassis to locations on the board, and then soldering the colored leads from the decoder to the corresponding locations.

Below is an example of a Digitrax DH126 installation using that mathod.

One complication of this method is that the motor contacts from the PC board go via a sprung brass finger to the top motor brush and a screw to the motor frame. These, I've discovered, aren't necessarily reliable contacts.

So I gave this some thought and decided to try eliminating the PC board itself, while retaining the plastic base below it that clamps to the frame. This will retain the brass headlight tube. The leads for track power from the trucks are long enough that I can splice them in the middle and attach those splices respectively to the left (black) track power lead and the right (red) track power lead from the decoder. In my case, I was almost out of heat shrink tubing due to the lockdown and had to scrounge odd scraps to insulate these connections.

Then I jammed a close-enough brass screw into the hole in the top of the motor frame. The screw provided with the model won't take solder, which is one reason the PC board installation isn't completely reliable. I soldered the orange lead from the decoder to this and the gray lead to the top of the brush in the motor.

Then I replaced the incandescent headlight bulb with a wired 12-volt 3mm LED, which was a good fit in the brass tube that comes in the model. I soldered the LED leads to the white and blue wires from the decoder and used more scraps of heat shrink tubing to insulate the splices. The tube snaps back into the plastic mount that I kept after tossing the PC board. A photo of this install is below:

While this method involves a little less work than cutting the PC board, there's a gotcha, in that it's easy to trap stray wires between the shell and the chassis, which makes the model very noisy, so you have to remove the shell again and be sure the wires are properly tucked in.

The model I converted in this project is pretty beat up, since it's been in the collection more than 30 years. But as a layout model, it's a very smooth and quiet runner. I notice in the photo below the front coupler still needs to be straightened.

I checked eBay and see that Atlas FP7s are pretty easy to find, and most go for well under the $99 retail of the 1990s models. I'd say that if you have one already, it's worth converting, but I wouldn't go out of my way to buy one just to convert it.