Clear-Com Communication Systems
Encore System Installation Instruction Manual
1-23
SYSTEM CHECKOUT
Before you turn on the power, perform the following tests:
CHECK TERMINATION
There should be one and only one termination for each channel in the
system. This termination is usually 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:
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 jumpers inside the unit. Consult
the unit's manual for the location.
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
resistance of 2,000 Ohms indicates a double-termination. If a
double-termination is indicated, locate the other terminated
Power Supply or Main Station and set its termination to OFF.
3. Repeat for the other channels.
4. Check resistance between Chassis Ground and pin 1. Using an
Ohmmeter, measure the resistance 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 individual 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, preferably 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, but a value of 4 to 10 Ohms is acceptable.
To Next Page
Loading...
Need help?
General
