Lenz Silver Mini in an Athearn F59PHI

Years ago I had presented an installation for the Athearn F59PHI on my old web site and later included it in this blog as a post.  In that installation I had used the original PC board that was in the engine and the decoder I used was the Digitrax DZ121 which at that time was one of the smallest decoders available.  Here is a link to that post.

Recently I was asked to replace an existing installation of a Digitrax DN121 decoder with a new Lenz Silver Mini.  The PC board had been removed from the locomotive.  So this post will show a different method to install a decoder in this loco that was not available in a DCC version and that no after market decoder board has ever been offered for.

The original installation is seen in this photo.  On this installation, the LED's were not in alignment to get any light into the lenses, particularly the ditch lights that are on this model.

For that reason I felt there would be an advantage to having the LED's and resistors mounted on a board of some type.

This is the Lenz decoder.  Notice how it does not have any heat shrink over it.  That means care must be taken in it's placement so it does not short on any part of the frame.  Also, the wires are more easily broken off from this decoder than those with heat shrink.

My solution to the wire problem is to place a small length of 3/16 inch heat shrink over all the wires near the decoder as shown here.  This acts as a strain relief and will protect the wires being broken off from the decoder during handling.

After removing the motor from the motor saddle and marking at least one of the sides of the motor to keep it's correct orientation, I removed the little tabs that would have held the board in place if there had been one.

A stock board from an Atlas GP40 fits just right into the top of the motor saddle and with some modification it can be used as a replacement board.

I aligned the board so that the front LED is at an equal distance from the front of the frame as on a stock Athearn F59PHI. The black line across the board and saddle mark this alignment.






Notice in the photo above that the little bars on the motor saddle that go across the motor contact wipers on the stock mechanism are gone on the saddle we are using.  This had been removed in the original DN121 installation.  If the loco you are working with is a new installation, this should also be cut.  Too see this step refer again back to the earlier post on this model.

This photo shows the modifications made to an Atlas GP40 board to make it fit into the frame of the Athearn F59PHI.

The polarity of the front LED is reversed so that the anodes of both LED's will be tied together.

I use E6000 adhesive from Tap Plastics to secure the board to the motor saddle and then the decoder to the board.  Because there is no heat shrink on the decoder, it must be placed on a spot where there is no exposed circuitry.

The white, yellow, and blue wires are soldered to the board as shown in this photo and the other wires are trimmed to 2 inches in length.  Keeping them long will make it easier to put things back together.

Route the wires down through the openings in the saddle.  Remove the brush holders from the motor, solder the wires to the brush holders, then after they have cooled, re-install them in the motor. Then connect the red and black wires to the contact strip.  Keep the solder joints small, if needed make the openings in the saddle a little bigger.

On this model the top of the shell is removable so in this photo the installation can be seen after the shell is re-installed on the mechanism.

Several areas to to watch out for are pointed out.

Done !

Lenz Silver Mini in an Atlas Classic GP35

One of the Classic releases from Atlas were the GP35's that were closely based on the mechanism made for them by Kato several years earlier.  The Atlas Classic GP30 also uses the same mechanism as the one shown here.  At first glance this would seem like a straight forward replace the frame type of installation but as I discovered there are a few extra tricks that are worth covering.

If you look at the frames for the Kato made model and the Classic models made in China, they seem identical in every way.  They both even have the same part numbers on them and copyright Atlas 1992.

There is a critical difference and it's important not to get them mixed up.  The photo on the left shows the right side frames from each model.  The size of the bushings used on the Classic version are slightly smaller and where they fit in on the frame is also slightly smaller.




A quick way to check is to test fit a bushing from a Kato made model. If it fits easily then it's a frame for a Kato made model.  If it's a tight fit or won't fit then the frame is for the Classic version.

I was quite confused about this until John from Aztec set me straight.  The Aztec part number for the milled frame for a Kato made model is TM3001 and for the Classic model it is TM3016.

Because the outside of the Kato made and Classic frames seems identical, I wondered if the shells are interchangeable.  After swapping around several shells and frames I was able to confirm that yes, they are interchangeable.  So now on to the decoder installation.

This model normally comes with bright white LED's on a PC board very similar to the one used on the Kato made model.

On some of them there is a small component added to the solder side of the board.  This was added to suppress the flickering of the LED when the engine was running in the reverse direction in DC operation and will not be needed after the decoder is installed so it should be removed on both boards.

On the front LED board only there is a chance that the LED lead on the left side can short on the left side frame as shown in this photo.

The LED needs to be removed, a small tubing place on this lead of the LED, then the LED re-installed.  The Kato 77A LED board already has tubing on it's LED so I took some from those to use here.

I have also found some of these Atlas boards that have the circuit traces both sides (top and bottom) of the board. These have to have both sides cut to fully isolate that part of the board from the frame.

This photo shows the component side which normally does not have any circuit traces.






For the wire lengths I followed the Aztec instructions except that I added the blue wire and cut it to the same length as the yellow wire.

   Black & Red = 1-3/4",  White = 1-7/8",  Orange = 1"
   Yellow & Blue = 7/8",   Orange = 1",   Gray = 1-5/8"

This photo shows a summary of all the steps I did to get the decoder ready to install.  The wires on the Lenz decoder are soldered right at the edge of the decoder and I felt they might get broken during handling so the first thing I did was to gather them together in a heat shrink band.

This decoder had no heat shrink covering and it components were exposed.  This was the method I used to insulate it from the frame and from the rear LED board.

A scrap of .020 thick plastic was cut to fit on the frame, then the decoder was secured with some Kapton tape.  The Kapton tape is trimmed to fit around the bumps on the sides of the frame that hold the shell in position.

Here is a photo of the completed mechanism from the right side.  The gray decoder wire gets around the motor to the bottom brush using the slot milled in the right frame side.