Tuesday, February 4, 2014

Lenz LE0511W in an Atlas MP15DC

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.