Converting the Carrera GO!!! Dodge Viper to Digital 143

By Michael Ashton

I have a Carrera GO!!! Dodge Viper that I would like to race on my D143 track. This entails installing a D143 decoder chip in the Viper. Technically, this is not an overly complex task, however, the larger obstacle is the fact that the D143 decoder chip is not available as a separate product from Carrera. This means that the only source for a D143 chip is an existing D143 car. Fortunately, I happen to have a D143 Ferrari F12 Berlinetta "street" car that I do not need for digital racing. Therefore, the Ferrari will become the "donor" vehicle. The D143 chip in the Ferrari will be transplanted to the Viper and at the end of the process, the Ferrari will become a GO!!! car — nothing wasted here.

Preparation

Below is a photographic list of the minimum tools required to remove and install the decoder chip:

1. A relatively low wattage (≈ 30 watt) soldering iron.
2. A hobby knife with a fresh, sharp blade.
3. A scribe or hole punch (a sharp nail will do).
4. A small tip Phillips screwdriver.
5. A 1/8" and a 5/16" drill. 

The above tools will allow the task to be completed successfully. Naturally there are additional tools which can make the job easier, quicker and the results more professional. These tools will be pointed out later in each step of the process where they are used.

Let's take a look at a side-by-side comparison of the GO!!! and D143 chassis.

Below right is the D143 chassis with the chip installed. The yellow arrow highlights the screw that holds the chip firmly in place. The red arrow indicates the point where the lane change LED emitter fits inside a cylinder that forms the opening through the underside of the chassis. It is through this opening that the emitter sends the lane change signal to the sensors in the lane change track section. The inset photo shows a closeup view of the LED emitter seated in the cylinder, indicated by the red arrow.

Above left is the Carrera GO!!! Viper chassis that will receive the D143 chip. Installing a D143 chip into a GO!!! chassis is made much simpler by the presence of the D143 chip mounting post that will be used to secure the chip in place with the mounting screw (yellow arrow), and a solid plastic post into which a hole will be drilled to create the opening for the lane change LED emitter (red arrow). Both posts are in the correct position required for accurate communication between the emitter and track sensors, so no measuring is required.

A few cautionary notes:

• It is quite possible that the modifications described in this article will nullify any manufacturer's warranty that may still be in effect. It is, therefore, important to test the digital functionality of the donor car prior to proceeding in order to insure that you have a good D143 decoder chip.
• This conversion is not particularly difficult, however, basic skill and knowledge of soldering, and its attendant safety issues, are required.
• It is strongly recommended that when transplanting a D143 decoder chip from one chassis to another that the chip/motor assembly be removed and installed as a unit. This will preclude the need to de-solder and then re-solder the chip connectors to the motor terminals, thus averting the risk of overheating the chip components and/or the motor itself. It also insures that a motor with the appropriate specifications for digital operation is used.

The Steps

1.) Remove the bodies of both cars from their respective chassis by unscrewing the mounting screws located at the front and rear of the underside of each chassis.

2.) Remove the D143 chip from the donor chassis.

a.) First, de-solder the motor lead wires from the pickup contacts (see the following photo):

Additional tools employed here are a soldering stand, used to free both hands by holding the chassis in place, and a pair of surgical forceps to pull the lead wires from the pickup contacts when the solder melts. Note that the front tires have been removed to avoid damage from the soldering iron tip. The front wheels were not removed because the front axle tips are knurled. So removing the wheels would likely have caused irreparable damage to the hubs. Exercise caution when soldering near these wheels.

b.) Remove the decoder chip mounting screw, as shown in the photo below.

c.) To remove the motor/chip assembly, first gently push the hole punch or a small flathead screwdriver through the opening of the motor mount on the underside of the chassis, as seen below. Repeat in the opening on the other side of the motor mount. Take your time and do this gently in order to avoid damaging the motor mount tabs that secure the motor in place.

This will cause the motor/chip assembly to pop up out of the motor mount, shown in the following photo. The assembly can then be lifted up and forward, separating it from the chassis. The red arrow points out the LED emitter.

Below is the motor/chip assembly, safely removed from the donor chassis. Note the tabs at the front of the motor mount (just behind the chip mounting post), still in tact.

d.) Repeat the above steps a.) and c.) to remove the motor from the GO!!! Dodge Viper. The difference is that there is no decoder chip to deal with.

3. Prepare the Dodge Viper chassis to receive the D143 decoder chip.

a.) Drill a small pilot hole in the center of the solid post that will house the LED emitter. I used a pin vise and a very narrow diameter drill as shown below. But the hole punch or even a small sharp nail can be used.

Absolute precision is not necessary, but try to be as close to the center of the post as possible.

b.) You could probably drill the final hole now, however, if you have a drill set, work your way up to the final hole size in several gradual increments. This will make the drilling easier and is less likely to cause damage.

c.) Use the 1/8" drill to create the final opening in the top of the cylinder. Drill all the way through the chassis turning the drill by hand — do not use an electric drill for this. See the following photo.

The finished opening as seen from the top is shown below. The hole is not perfectly centered but this is not a problem because the LED emitter and the lane change track sensors have a relatively wide angle of sensitivity.

e.) The underside of the opening is shown in the photo below. Note that this side of the opening is slightly larger than the top, or beveled. This is accomplished by drilling up from the bottom by about 2 mm with the 5/16" drill. Be very careful not to drill too far up. The edge can be smoothed over using the hobby knife and some fine sandpaper. This is an important step because the beveled opening provides a wider field of transmission for the LED emitter.

3.) Install the D143 chip/motor assembly.

Just reverse the steps of motor/chip assembly removal from above. Slide the pinion gear through the circular opening in the mounting bracket in front of the crown gear until it meshes properly with the crown and the motor shaft fits into the channel between the two parts of the gear. Make sure that the LED emitter is lined up to fit into the cylinder opening. Then press downward on the motor can and chip until the motor snaps into place and the LED is seated into the cylinder. Insert the mounting screw through the hole in the chip and into the mounting post below, then turn the screw all the way down until it is tight and the chip is firmly seated and the LED is all the way into the cylinder. Finally, solder the motor lead wires to the pickup contacts.

The two photos that follow show the motor/chip assembly installed in the Dodge Viper chassis. Note the orientation of the motor lead wires for correct polarity. The red arrow in the first photo highlights the proper positioning of the LED emitter.

When viewed from the underside of the chassis, the emitter should appear as shown in the photo below.

The GO!!! motor removed from the Dodge Viper can be installed in the Ferrari in virtually the same manner as depicted above for the Viper. Again, the only difference is that there is no decoder chip and LED emitter to deal with.

Finally, reinstall the Dodge Viper body onto the newly converted chassis and we now have a D143 Viper ready to test on the D143 track.

The newly converted D143 Doge Viper was tested on an oval skid pad for about 100 laps of continuos lane changing and straight pass throughs. During this test there were no missed or spurious lane changes observed.

Upon completing this project a couple of things occurred to me: first, the Dodge Viper is available only as a GO!!! car, so I now have a D143 Viper which is somewhat unique; second, apparently GO!!! cars are pretty easy to sell on Internet auction sites and slot car forums. So if there is no need for the [converted] GO!!! donor car, this will help reduce the overall expense of the conversion significantly. Somewhat cool on both counts, I think.

_Michael Ashton