RS-3 Generation 2 QSI Install

R.J. and I did an install in a second generation RS3.

We basically followed what George Schreyer had on his site.

He called the generation 2 RS-3 the "new type" on his page.

There is a board in the shell that has the switches for smoke, lights (cab & marker) and motor. This board has a small daughter board that has a 6 volt regulator on it. The regulator is on a small daughter board, and it uses a Motorola IC as a switching regulator. (The idea is to allow full brightness at lower voltages, i.e. about about 6 volts on, the bulb will be at full brightness.

Below is a picture of the switch board with the daughter board and you can see the IC on it.

Below is another view of the other end of the switch board and daughter board. You can see the capacitors and inductors for the switching power supply.

We removed the little 6v regulator daughter card from the switch board in the shell. The easiest way is to cut the caps and inductor off the back side, and then slice through it with a dremel, so it's in 2 halves. Then desolder from the back side.

Here are pictures of the back side and component side of the switch board.


We then used George's idea of "off boarding" a 7805 regulator and a 10 ohm dropping resistor. Radio Shack has a 10 watt one, so we used this instead of the 5 watt one George did.

Now on to wiring up the QSI to the loco. Below is a picture of the main board on the chassis.

You can see the "jumper plug" with it's 2 loops of red and black wires above.

We then cut the loop of wires on the "jumper plug" that connects the track pickups to the motor.

Looking at the long board on the chassis, at the very ends is where there are 2 sockets for the truck. You can see that there is a 2 pin socket and a 3 pin socket. The track pickups are the 2 pin plug, and the motor is connected to the 3 pin connectors.

The picture below shows which plug connects to what on a truck:

To hook in a decoder, you need to disconnect the motor from the rails.

Luckily this generation is the first generation to make it somewhat easy. There is a 4 pin plug that jumpers the motor to the rails. By cutting the loop of wires so you have 4 separate wires, you accomplish this.

The schematic on George's site shows the "outside" wires on this plug are the track pickups. This was not the case our loco. 

In our locomotive, the ouitside red wire was connected to the firemans side. The black wire immediately next to it is the engineers side.

Note well: this is for "long hood forward" so it's reversed for most western  railroads.

So for a QSI "Magnum" board, the engineers side (black) is TK+, and  the fireman's side (red) is TK-.

The motor leads are the 2 wires on the plug that are closest to the center of the chassis circuit board. (you can see they go to the 3 poin connectors).

On our loco, the red wire went to M+, and the black wire went to M-.






Weather Underground PWS KCACARLS78