Friday, August 26, 2011

DZ121 in an Athearn F59PHI

This how to first appeared on my old web site in June of 2004.  Since that time the decoders mentioned have been replaced with newer models.  I would suggest the TCS M1 or Z2, or the Digitrax DZ125.  I don't think a board type decoder was ever made for this engine.

There is plenty of room for a small decoder without any modification to the frame. In this example I used
a Digitrax DZ121 but a DZ123, DZ143, or any similar sized decoder would also work.
The key to this installation is using the existing circuit board. The drawing of the board at the right shows all the steps taken to modify the board and then make all the connections to complete the installation.  Below are several photos to help clearly see what the installation should look like.

In this photo you can see where a section in the middle of the board has been removed for the decoder.  I used a Dermal tool with a cut off disk to do this.

After that the holes for the resistors get drilled & the circuit traces between the holes get cut. Then reverse the Led on the forward end of the board.

Next install a 270 ohm 1/4 watt resistor at each pair of holes. You will need to scrape away the green plating from around the holes before soldering.

An update to the way this was done in 2004 would be to change the yellow LED's to the bright white type of LED's. If this is done you may also want to change the 270 ohm resistors on the board to a higher value.

Note in the close-up to the left how the circuit trace has been cut between the points where the resistor is soldered.  This was also done with a Dermal tool and cut off disk.
These are the wire lengths that I use for this installation.

Black = 1-1/8"
Red = 1-1/16"
Orange = 15/16"
Gray = 1"
White = 1-3/8"
Yellow & Blue = 3/4"

Remove the motor brush mounts from the motor before soldering the orange and gray wires to them.

Then solder the white and yellow wires to the board at ends of the resistors that are away from the LED's as shown in the photo.

Cut the plastic bar that goes across the top of the wire channel on each side.  Reinstall the motor brush mounts with the orange wire going on the right side and the gray wire going on the left side.

Then solder the black wire to the tab on the bottom of the left side and the red wire to the tab on the right side.  Finish by tucking any excess wire length under the board and placing a piece of scotch tape over the decoder to hold it in place.