Clear-Com PIC-4704 - Manual (Page 21)

P I C - 4 7 0 4 , M A - 7 0 4 & A X - 7 0 4 I F B S Y S T E M
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MAINTENANCE
The table of possible problems on the next page, which generally involves system
wiring, covers only the most likely problems. In any troubleshooting effort, keep
these points in mind:
1. The power for all units in the system is routed from the power supplies
through the PIC-4704.
2. All access stations (MAs and AXs) and the talent receivers are connected across
the IFB lines in a bridging configuration (high impedance).
3. Each IFB line is terminated by its associated PIC-4704. The termination is
about 220 Ohms AC, and approximately 5,000 Ohms DC.
4. Three different types of signals are present on the IFB line:
a. Cue audio, which originates from an access station’s microphone.
b. Program audio, from the associated PIC-4704.
c. Interrupt control signal, a DC voltage which also originates at an access
station.
5. The cue audio and all control signals for operation of the AX-704 stations at
any given location are supplied by the MA-704 station at that location.
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