This installation was first presented on my old web site in January 2006.
The Atlas MP15 had just come out and it was designed to be DCC ready but no decoder board was available for it yet so I decided to try to install a small wired decoder in it. The Lenz LE0511W was one of the smallest available at that time.
After disassembling the engine, modify the LED board as shown.
Remove the LED from longer hood end of board and save it for later.
Decoder wire lengths:
7/8" inch - Red, Black
1 inch - Orange, Gray, Blue
1-1/4 inch - White
1-3/8 inch - Yellow
Scrape off
the green coating from the circuit traces near the frame contacts on the
LED
board to expose bare copper and solder the red and black wires, observe
polarity.
Reverse the polarity of
the LED by removing it, flipping it over, and then re-soldering it. Feed the
yellow wire through the hole from the top side to the bottom side and solder as
shown.
Place a 1/4
inch length of 3/32 inch heat shrink over the white wire and solder the
white wire to the LED lead on side where the rim is flattened. Place a 3/8 inch
long length of 1/8 inch heat shrink over the blue wire and solder and 1K ohm 1/8 W resistor to the blue wire. Then solder the other end of the
resistor to the other LED lead. Slide heat shrink down and heat.
This motor
design has a small PC board with two contacts sticking up. Cut these
contacts to about half their original length.
Cut two lengths of
3/32 inch heat shrink about 3/16 inch long and place these over the gray
and orange decoder wires.
Solder the orange and gray wires to the
shortened motor contacts. Use a low heat setting and be extra careful
about the heat being so close to the motor housing. Observe the correct polarity of the wires.
Slide the heat shrink down over the
soldered connection and apply heat from a heat shrink gun.Again, be
careful of damaging the motor housing.
This is what the completed decoder assembly should look like
with the PC board, motor, and front LED connected.
Notice the small
red band over the wires near the decoder. I've found that is helps
protect the wires connections to the decoder while handling. This can be
cut with with small scissors and removed after the decoder is
in place
| When re-assembling the engine it is very important to
get all 4 of the motor saddle tabs properly into the notches on the
frame. |
The Lenz decoder does not have any insulation over it the
way a other brands do so we need to insulate the frame where the
decoder is going to be.
Place a piece of 1/2 inch Kapton tape on the top
of the
front section of frame. Trim any excess from the sides.
Here is the re-assembled mechanism with the decoder
properly installed. Lay out the wires in the channel at the top of the frame halves so they are as flat as possible. Lay the wires to
the front LED out so that the bulge from the resistor is where the gap in the
frame is. Put the decoder on top of the LED wires and angle the LED slightly upward. Secure wires and decoder with scotch tape.
Re-install the shell onto the mechanism. The shell should rest on
the painted rails that are part of the frame.
If the shell will not go down all the way, the LED on the board
may not be properly aligned. There is a black plastic light shroud inside
the shell at the hood end. Fish it out and carve a notch in it as shown. This should allow the shell to go
down all the way. Put it back into the shell as it was before. Try
installing the shell again.
Decoder boards made specifically for this model have been available for some time now but in case you ever want to try a wired decoder this is how it's done.
