GAI-Tronics 495-001 Mine Dial / Page Phone Interface Cabinet - Manual (Page 5)

Pub. 42004-198D
Model 495-001 Mine Dial/Page Phone Interface Cabinet Page: 5 of 22
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The All-Call/Merge assembly allows all-station paging in the normal dial access, or in the event of a
telephone switchboard failure, system-wide paging with push-button page switches on the 491 Series
Phone front panel. This assembly includes an audio amplifier and three relays, and is built on an 8-inch
square plug-in chassis plate. Refer to Figure 4.
Figure 4. All Call/Merge Assembly 10431-001
DC power to operate the interface circuitry ordinarily comes from an ac-operated power supply located
within the Power Supply/Metering Panel assembly. See Figure 8 and Figure 9. Space is provided within
this assembly for a rechargeable, non-liquid, lead acid 12 V battery. The battery backs up the system in
the event of power supply failure or ac power source failure. The Power Supply/Metering Panel assembly
contains meters and switches to indicate the state of the power supply and battery. The assembly
occupies the space of a 7
× 19-inch rack panel.
The battery charging circuit and power supply to battery switching system is packaged separately in the
DC Power Transfer assembly. This assembly is built similar to the All-Call/Merge assembly for service
by substitution and mounts within the housing. See Figure 10.
The housing for All-Call/Merge and DC Transfer assemblies occupies the space of a 10.5
× 19-inch rack
panel and houses the two assemblies described above. The housing includes four terminal blocks for
input/output connections. See Figure 7.