Sunday, November 21, 2010

TCS M1 in a Walthers GP38-2

This how to episode first appeared on my old web site in December 2008.

The Walthers GP38-2 did not come with any provision to install a board type decoder but has room for one of todays small wired decoders.  Follow along as I install a Train Control Systems M1 decoder in this one.
As shown in the photo on the left the design of the engine leave space in key areas that we can use.  The existing PC board will be modifiyed and re-used.

Start by fully disassembling the locomotive and make a mark on the top of the motor.
Strip the PC board of all it's parts.  Then make the modifications shown in the photo on the left.  Save teh two resistors from the locations R3 and R4 that are marked "561" and re-install them at locations R1 and R2.
The LEDs that come with the Walthers GP38-2 are standard yellow ones.  I am going to upgrade to sunny bright white LEDs.  I remove the stock LED's from the board and use them as a guide to bend the leads of the new ones to the correct length.
Next prepare the decoder.  Cut the blue wire to a length of 3/4 inch.  Strip about 1/8 inch insulation from the end and from one end of the piece of blue wire that was cut off.  Twist the two stripped wire ends together and tin.
Now solder the two twisted together and tinned blue wires to the spot shown in this photo. Then route all the remaining wire ends through the hole to the top side of the PC board.
Next Solder the black and red wires to the locations shown in this photo. 
Next trim the yellow, blue and white wires to a length to reach the spots shown in this photo.  Strip and tin the ends and solder the wire ends to those locations. 
Cut the orange wire to a length of 1-1/4 inch from where it comes through the hole in the PC board and cut the gray wire to a length of 2 inches.  Strip and tin the ends and solder to the brush caps after they are removed from the motor.



Re-install the brushes, springs, and brush caps in the motor. The gray wire goes to the bottom and the orange wire goes to the top of the motor. Use a small amount of Walthers Goo to secure the gray wire into the groove filed into the motor housing in the previous step. Then wrap Kapton tape all the way around the motor where the brush caps are to insulate them from the frame.   Now reassemble the motor and worm gear assemblies into the right side frame as shown. With this type of mechanism that uses the rings to support the motor great care must be taken to insure that the rings are properly seated into the frame.

With the frame still laying on it's right side, place the washers that separate the frames into the holes and re-install the left frame. Make sure that the mounting rights are seated properly into both frames then re-install the screws and nuts.

Get the front PC board contacts started first, then being careful not to pinch the orange and gray motor wires guide the back of the board down onto the frame. Then push forward to fully seat the boards contacts into the frame.  When the board is fully seated into the frame it should look like the photo above. Lay the motor wires down over the board in the area above the motor. If necessary, secure them with some scotch tape.

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