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SMD2 and Kato Unitrack Switch Machine Application Information

Instructions for adding resistors to the SMD2:
As discussed in the SMD2/SMD8 application information, the Kato unitrack electric turnout has two electrical connections as compared to three for other solenoid type switch machines. Since the SMD2 provides power on the common connection, two resistors are required to be connected from the common to power the machine. Figure 1 below shows how the resistors are electrically connected. These resistors can be physically located external to the SMD2 or can be soldered to the bottom of the SMD2 circuit board.

Kato switch diagram
 
The picture below shows the bottom of the SMD2 circuit board. The resistors must be connected between the Common terminal and the Throw and Close terminal for each output. Notice the arrows pointing to the C, t and c labels on the board. These are the locations where the resistors  are soldered.
 smd2 board with arrows

The picture below shows the resistors soldered to the bottom of the SMD2 circuit board. The resistors used are 22 ohm 1/2 watt (Radio Shack 271-1103 or equivalent). Use a piece of electrical tape to keep the resistor leads from shorting to other solder joints.
smd2 board with resistors