Warning: It should be noted that this conversion may void some or all of your warranty.

Note: The decoder manual was followed in all items related to the decoder, its specifications and connections. This also means it was tested on Loy's Toys Decoder tester to ensure the decoder worked before starting.

The first item I did was to test the unit for current draw to decide what decoder I would use.

Current free. .45 amps.

Current locked 2.25 amps

Disassembly

There is one screw holding the front truck on which I removed so I could remove the screw which holds the smoke box (try to remember how the spring comes out for the front truck) and two more screws on the sides of the firebox. The two frame extensions that hook to the very rear of the cab require a bit of spreading on the cab piece to remove them from the cab. I cut the wires from the tender plug as close to the board as possible and unplugged the four pin plug from the power unit. The firebox light was loose which may have been hot glued at one time so it just came apart

The motor is encased in a diecast housing and one of the rail terminals is common to motor terminal so separation was required. It would have been nice if the plug with the four leads had been separate.

Motor Disassembly

I removed the cylinders from the base. They just pried off. Of course the cross head rods fell out

I then remove the four wheels on each side by removing the four phillip head screws holding the wheels on. Once the screws were out the wheels slipped off with a bit of prying. I marked the wheel sets left and right and made a note of the quartering as they will go on 90 degrees advanced or retarded.

Now I have the die cast block with four axles sticking out, in my hand. I take out the four phillips head screws holding on the right side only (You Do not Need to take out the left hand screws.) The right side comes off exposing the motor and all the mechanism.

You then remove the motor and plug which are attached to each other DO NOT TAKE OUT THE AXLES OR THE DRIVE ROD OR ANYTHING ELSE. If you look at the plug and the motor you will see the upper motor terminal is soldered to two plug terminals. I unsoldered the plug from the motor, ground and with my Dremal ground a separation in the plug soldier so I was able to twist it 90 degrees, then twisted the motor terminal 90 degrees and soldered it back together having the top motor lug solder to the other inside that was soldered to the track terminal.

The other two terminals connect to the split motor housing to feed power from the wheels to each side. See photo for details. You then reinstall the motor and plug. For some reason the lug looked closer to the side block than I liked so I removed the motor and plug again and added a bit of black tape for insulation. I then reassembled the diecast side making sure the front and rear axle were lined up with the drive gear and each other. The two center axles have gears but free float. (note; They look like they could be used as spares but I did not confirm this.) When I had it assembled I checked the following. Unit turns with no binds, which can be done through a hole, which exposes the drive gear. With an ohmmeter I checked the conductivity between each sides wheels and its appropriate prong on the plug and the continuity through the motor which is 5 ohms, and also that the motor was indeed isolated from both sides. I then took DC to the two center prongs and ran the unit just to ensure all was well. I reassembled the wheels ensuring it was quartered correctly and then retested the unit with DC to ensure it ran smooth. Watch out for the hanging piston rods when they spin. Set the completed assembly away till later.
 
 

Cab and Boiler

Slide the brass rods back from the cab which are attached to the boiler. Some came right off and some dangled for the rest of the time. Remove the two screws holding the roof on and remove the roof. Remove the two screws holding the cab on and slide it out. Mine was tight, but it came. Somewhere in that, the rear of the boiler fell off with the gauges and throttle lever. Inside the rear of the boiler is a circuit board held on to the boiler with a three way toggle switch. Remove the nut from the rear of the boiler and the switch will move forward and come out taking the circuit board with it. Mine needed a gentle tap. I unsoldered all wires from the circuit board and the firebox bulb and put it in my junk box. The firebox bulb would not be reused nor would the circuit board. The covers fell off the marker lights and I put them away till later. I next identified and marked the wires for the headlight, marker lights and smoke unit. I found it strange that they were a mixture of small and larger wires for the various items. Mine were as follows: Smoke unit, large blue and medium black and it drew .3 amps. Head light small white and it drew .04 amps. Marker lights which were large blue and small white and they drew .04 amps each

During this time I had been looking for the best place to mount the decoder and I wanted to use the following criteria. Attached to the top half for easy disassembly ( I learned earlier if you make things easy to come apart they seldom need to). Attached to metal for good cooling. I decided on the Digitrax D580L and I decided on top of the boiler weight would be a good spot, but there was not quite enough room, so I removed the boiler weight and cut out a notch at per the photo. I also took the piece I cut out and added it back on to the front of the lead so I did not loose any mass. The weight with the decoder attached was reinstalled.

I then cut a piece of perforated board and cut it just so it would fit inside the back of the board where the old circuit board was. My track voltage is 22 volts and the bulbs in the unit were 12 volts. See the board wiring diagram, but I did the following. Added a 24 volt relay to control the smoke with F-3. Joined the two 12 volt marker lights in series and controlled them with F-5. I added to the board in front of the firebox door a red and yellow 12 volt bulb in series attached to F- 4. I will later set this FX function to flickering. Added a 150 ohm resister @ 1 Watt to the circuit and controlled it with the normal white wire. I also used the board to attach the red and black decoder wires to, as I had to run it to the smoke and to the tender. See schematic for details.

                            Faces Firebox                                                               Faces Front of Engine

Contrary to decoder instructions the red decoder wire goes to the left rail in G scale and the black wire goes to the right rail so they were connected from the board to the correct wires on the plug. I then attached the gray and orange decoder wires directly to the wires on the plug. The orange decoder wire goes to the blue on the plug and the gray decoder wire goes to the brown on the plug. I attached these directly and did not go to the board. I added two wires to the board attached to the left and right rail connections, later to be attached to the tender plug. I added a 15 ohm 10 watt power resistor in line with the smoke unit to protect it from the 22 volt rail voltage. Since I had put the relay on the board on the same side as the new firebox lights I used a piece of double sided tape on the relay and mounted the board inside of the rear boiler piece. This allowed some space for the firebox lights. I made sure all wires had enough slack to go where they needed to be without any excess and I then reassembled the unit. All joints were shrink wrapped when soldered and I shrink wrapped all unused decoder lead. I did not install sound at this time and my intention is to use a small decoder in the tender to run the bell and whistle. I did this because if you use the same decoder you need a tender plug with six additional wires in it. I tested the unit disassembled to ensure all functions were working and the I reassembled the unit. Some notes on assembly. You need to have the rear boiler piece sitting loose in place. I assembled the cab first and did the roof last. Make sure you put the cylinder cross head rods with the small jog to the cylinder.

Note. I later installed a Sierra sound system in the tender, but used a small decoder in the tender so it was not necessary to run any additional wires to the tender. I tested this unit at our June 13, 1999 open house and it ran well.
 

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