Shure A120S User Manual

A120S In-Line Switch User Guide

GENERAL

The A120S Accessory in-Line Switch can be used to
add an On/OFF, Push-To-Talk, Cough Button, or Transmit­ter-Relay Keying function to a microphone or other device
rated at up t o 3 amps ac (0.5 Adc) 125V, non-inductive load.
The switch has gold-plated contacts for reliable perfor­mance even in low-current circuits. The switch is a double­pole double-throw type for maximum versatility. Its pushbut­ton combines with a rotary knob to provide either
spring-return momentary or locking action.

The unit is supplied with a crimp-on strain relief tor

6.4mm (0.25-in.) diameter cable and with a flex relief for ei­ther large or small diameter cables. The permanently at­tached belt clip can be rotated on the case to any of four posi­tions for the most convenience in use.

OPERATION

Switch Function Rotary Knob Position

On/Off (Button remains down

until depressed a s econd t im e)

Push-To-Talk (Button remains

down only while depressed)

Locking

Momentary

Locking the Switch Button Down

The switch button can be locked down by following
these steps.

1. Turn the rotary knob to locking.

2. Press the switch button down.

3. Turn the knob to Momentary.
The button will remain locked down until the knob is re-

turned to locking and the button is depressed again.

THICKER OR MULTIPLE

CABLES

SINGLE NARROWER

CABLE

FLEX RELIEF

FIGURE 1

2. For one 6.4 mm diameter cable (0.25 in.), crimp the
strain relief to the cable making sure the eyelet is to­ward the raw end of the cable. Leave enough raw
cable above the strain relief to permit soldering the
individual conductors to the switch terminals.

NOTE: For all other cables, loosely knot the cable above
the flex relief to form a strain relief. Leave enough raw
cable above the knot to permit soldering the individual
conductors to the switch terminals.

SWITCH INSTALLATION AND WIRING

1. For thicker cable (e.g., one 6.4 mm [0.25 in.] diameter
cable or two 3.8 mm [0.15 in.] diameter cables), cut off
the bottom of the flex relief at the rib. For narrower cable
(e.g., one 2.3 mm [0.39 in.] diameter cable), use the en­tire flex relief as supplied. Thread the cable (s) through
the flex relief.

2002, Shure Incorporated
27B8064 (BI)

STRAIN RELIEF FOR ONE

6.4 mm (0.25 in.) CABLE FOR OTHER CABLES

KNOTTED STRAIN RELIEF

FIGURE 2

Printed in U.S.A.

3. Solder the conductors to the switch terminals to ob-

tain the desired function (see Figure 3 for switch
configuration.) Take care no to leave long bare con­ductors that may bridge across terminals and make
unintended connections.

NOTE: When the switch is used to make connections in
the middle of a cable run, It is very important to preserve
continuity in the cable shield. If a splice is necessary for
this, be sure it is insulated from other terminals, or you
may employ an unused switch terminal to make the con­nection. Leaving the shield discontinuous may cause
undesirable hum in a circuit.

TERMINAL SIDE OF SWITCH

ASSEMBLING THE SWITCH

FIGURE 4

FIGURE 3

4. Assemble the switch by inserting the tab on the bot-

tom back of the switch into the slot in the upper case
front. (See Figure 4)

5. Insert the flange in the flex relief into the slot be-

tween the case bottom and the small horizontal pro­jection.

6. If the strain relief is used, align its hole with the hole

in the center boss in the lower case front. Align the
cable to one side of the boss.

NOTE: If the cable is knotted to provide a strain relief,
the center boss in the case may be inserted through the
center of the knot with the cable lying to the side of the
boss.

7. Use the three provided thread-forming screws to
fasten the case back to the case front, making sure
not to pinch any leads. (If the strain relief is used,
make certain that it is captured by the screw through
the lower center back of the case.)

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