Adjustment Procedures
025-9416
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ADJUSTMENT PROCEDURES
OVERVIEW
The following procedures describe the level adjustments necessary to make the Model 640
operate properly. Each procedure should be performed following the initial installation process
and whenever the hardware configuration changes. For example, if the telephone line signaling
format changes, or if new options are purchased, the appropriate levels should be readjusted.
In addition to adjusting the paging terminal interfaces when hardware changes, some adjustments
should be performed as part of regular maintenance.
Measurement Conventions
The following conventions are used in each of the adjustment procedures.
All trunk level readings are expressed in decibels (dB) and AC volts RMS (Vrms). All dB read-
ings have been determined using a bridging (high impedance) AC voltmeter calibrated in deci-
bels referenced to 1 milliwatt dissipated into a 600 ohm load (dBm). All voltage readings have
been obtained using an AC true-RMS voltmeter measuring sinusoidal waveforms.
Note:
The measurements are NOT made in dBm because the line termination may not
necessarily be 600 ohm.
WARNING: Field technicians must be sure lines are connected (terminated) properly before
setting adjustments.
If assistance is needed to complete any of the adjustments, contact Zetron technical support.
TRUNK CARD LEVELS
The following procedures apply to both types of trunk cards (standard and 4-wire audio dual
trunk interface).
Each telephone interface line requires three separate adjustments:
•
audio level from the telco (labeled FROM TEL)
•
telco line balance R (labeled BAL R)
•
telco line balance C (labeled BAL C)
These potentiometers have been set at the factory, but usually need to be field-adjusted to match
actual phone line characteristics.
The voice audio on each telephone interface line has a gain control, which automatically
compensates for differences in caller loudness and call-to-call gain changes. The AGC KILL
switch is used in conjunction with the three pots to make accurate adjustments.
Summary of Contents for 640 DAPT XTRA
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Page 6: ...Statements vi 025 9416...
Page 20: ...Introduction 8 025 9416...
Page 26: ...Specifications 14 025 9416...
Page 96: ...Installation 84 025 9416...
Page 126: ...Optional Equipment Installation 114 025 9416...
Page 134: ...Voice Prompts 122 025 9416...
Page 174: ...Parts Lists and Schematics 162 025 9416 Schematic...
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Page 198: ...Parts Lists and Schematics 186 025 9416 RAM Disk 702 9386B ROM Disk 702 9389B...
Page 199: ...Parts Lists and Schematics 025 9416 187 TNPP Interface 702 9362C 2...
Page 200: ...Parts Lists and Schematics 188 025 9416 Terminal Block Adapter 702 9470B...
Page 201: ...Parts Lists and Schematics 025 9416 189 CONFIGURATION DIAGRAMS Dual Trunk Telco DID 024 0076A...
Page 202: ...Parts Lists and Schematics 190 025 9416 Dual Trunk Telco End to End 024 0077A...
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Page 204: ...Parts Lists and Schematics 192 025 9416 Dual Trunk Telco Ground Start 024 0079A...
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