Oakley OMS-820 - Manual (Page 15)

Connections
The power socket is 0.156” Molex/MTA 4-way header. Friction lock types are recommended.
This system is compatible with MOTM and standard Oakley Modular systems.
Power Pin number
+15V 1
Module GND 2
Earth/SCR
3
-15V 4
The SCR pad on the PCB has been provided to allow the ground tags of the jack sockets to be
connected to the power supply ground without using the module’s 0V supply. Earth loops
cannot occur through patch leads this way, although screening is maintained. Of course, this
can only work if all your modules follow this principle.
If you have used Switchcraft 112 sockets you will see that they have three connections. One is
the earth tag which is connected to the metal barrel of the socket. One is the signal tag which
will be connected to the tip of the jack plug when it is inserted. The third tag is the normalised
tag, or NC (normally closed) tag. The NC tag is internally connected to the signal tag when a
jack is not connected. This connection is automatically broken when you insert a jack. In the
OMS-820, we have no use for the NC lugs.
The ground tags of each socket can be connected together with solid wire. A single piece of
insulated wire can then be used to connect both the tags to the SCR pad on the PCB. Do not
connect these ground tags to any other ground.
The suggested layout uses just two sockets, and wiring them up is straightforward enough.
Use multistrand hook up wire to connect each socket’s signal lug to the relevant pad on the
PCB. There is no need to use screened cable for such short runs. Keep the wires short but not
taut. If you do insist on using screened cable then connect the screen to the socket’s ground
lug. Leave the screen unconnected at the PCB end. Use a bit of heatshrink tube to keep the
end from fraying.
The GATE socket’s signal lug goes to the pad marked GATE. And the RESET socket’s
signal lug goes to the pad marked RESET.
Now the OMS-820 has five switches. Wiring these can be confusing, so take your time. The
first switch to wire up is the EG/LFO one. This is connected to the three pads labelled MODE.
The SPDT toggle switch has three pins. The top pin of the switch should be wired so that it
goes into the bottom pad of MODE. The middle pin goes to the middle pad of MODE. The
bottom pin goes to the top pad. The two end wires therefore cross on their journey from
switch to the board.
The next switch to wire up is the GATED/RESETABLE switch. This is wired to the AUTO
pad. Again you need three wires to connect this switch, and again it is the top pin of the
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