Instruction manual

System Checkout

efore you turn on the power:

Check Termination

There should be one and only one termination for each channel in the system. This termination is usu-

ally set to ON at the main station or power supply. To ascertain that only one termination is present on

the channel, perform the following test:

1 Using a multimeter, measure the resistance between pins 1 and 3 on one of the Channel A XLR

connectors at the rear of the unit.

2 If the channel is terminated properly, then the resistance should measure approximately 4,000

Ohms. A very high channel resistance means the channel is not terminated. Channel resis-

tance of 2,000 Ohms indicates a double-termination. If a double-termination is indicated, Lo-

cate the other power supply or mainstation and set its termination to OFF.

NOTE

: The location of the termination switch varies with model. On some products,

the termination switches are on the rear panel; on others they are inside the unit.

Consult the unit's manual for the location.

1 Repeat for the other channels.

2 Check resistance between Chassis Ground and pin 1. Using an Ohmmeter, measure the resis-

tance from pin 1 on the main station or power supply to chassis ground. The measurement

should read 10 Ohms. A high reading (over 100 Ohms) indicates that the 10 Ohm resistor in

the unit has failed and requires replacement. Failure to perform the replacement will result in an

audible "buzz" in the system. A reading of less than 10 Ohms (or a short) typically indicates

that the shell and pin 1 of one of the interconnect cables are shorted together. Test the indi-

vidual cables until the culprit is located and repair or replace the cable.

NOTE

: PIN 1 and the shell of the XLR plug on the interconnect cables should NOT be

connected together.

Check Intercom Cable Resistance

For minimal crosstalk, the ground resistance of the intercom cables should be as low as possible, pref-

erably less than 2 Ohms. Disconnect an intercom line from the main station or power supply. At the

point in the intercom line furthest from the unit, connect a clip lead jumper between pins 1 and 2. Back

at the "powered" end, use an Ohmmeter to measure the resistance between pins 1 and 2. A value of

less than 4 Ohms is ideal.

Final Tests

After you turn

the power ON:

1 Check for proper voltage on pin 2 of any intercom line or jack in a channel. It should read 26-30

Volts.

2 Test for proper operation of Call Signaling. Activate the CALL SIGNAL on any belt pack or sta-

tion. The call lights on all other stations on that channel should illuminate and then go out when

the call button is released.

3 Adjust the sidetone null on all stations. (Refer to the manual for each specific unit for

instructions.)

Clear-Com PS-232 Power Supply