JST Connector

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Example of a decoder with a JST connector

JST is not a connector! It is the name of the manufacturer, which makes many connectors.

A JST Connector is a mechanism to connect a Mobile Decoder to its wiring harness. This means the decoder is removable and replaceable without any further soldering. The 9 pin version of this connector is covered by the NMRA standard.

JST refers to the component manufacturer, Japan Solderless Terminal Manufacturing Co. Ltd., of Japan, maker of the plugs and sockets used in these applications. The NMRA Standards refer to the JST part number for the socket as S 9B-ZR-SM2-TF.

Installing a decoder with this socket is similar to installing a Hardwired Decoder because the other end of the harness must still be soldered directly to the locomotive's pickups and motor terminals.

Connections

Pin 1 | Violet or Brown Function 2 (F2) Connect to the negative side of the function 2 device
Pin 2 | Black Left Rail Connect to the left rail pickup
Pin 3 | Grey Motor Left Connect to the motor terminal that was previously connected to the left rail
Pin 4 | Yellow Rear Headlight (F0) Connect to the negative side of the rear headlight
Pin 5 | White Front Headlight (F0) Connect to the negative side of the front headlight
Pin 6 | Blue Common (+ve) Connect to the positive side of all the functions (lights, etc.)
Pin 7 | Orange Motor Right Connect to the motor terminal that was previously connected to the right rail
Pin 8 | Red Right Rail Connect to the right rail pickup
Pin 9 | Green Function 1 (F1) Connect to the negative side of the function 1 device

Both motor terminals and all functions must be fully isolated from the rail pickups before installation.

The negative and positive sides of the headlights and functions are important if the devices are polarity sensitive, such as LEDs.

See Also