Specifications

77
Adjustment Procedures
Adjustment Procedures
Trunk Cards (702-9037 and 702-9117)
Each telephone interface line has four adjustments: audio level from the telco, audio level
to the telco, and telco line balance R & C. These adjustments have been set at the factory,
but usually need to be field- adjusted to match your actual phone lines.
The voice audio on each telephone interface line has an automatic gain control, which
automatically compensates for differences in caller loudness and call-to-call gain changes.
The adjustments outlined below are important. They affect the recording of background
noise, the compressing of speech silence, the decoding of DTMF keys, VOX disconnect
features (if used), and modem communications.
There are different revisions of the Dual Trunk, which have different adjustment methods
due to differences in the AGC circuit.
How to Identify Dual Trunk Revisions
1
The ballast lamps light when off-hook on DID, Ground Start, and some E&M configurations. You
will not see them on End-to-End Loop Start and in some E&M configurations.
To Tel Adjustment
The TO TEL adjustment can usually be left at the factory setting. Its setting is up to you. If
voice prompts or tones coming from the paging system sound too low, turn the pot
clockwise. If too loud, turn counterclockwise.
From Tel Adjustment
In general, leave FROM TEL in the factory adjusted position. If there is too much silence
deletion (voice recordings are incomplete, missing syllables from quiet or long distance
callers) then turn the pot clockwise. If there is no silence deletion (voice recordings have
Revision Description
A - C These boards have a single row of TEST points on the front panel. The ballast
lamps are on the rear part of the board behind the matrix plugs, and thus can
barely be seen when on (when the trunk is off-hook
1
). The revision letter is
written near the white nylon connector near the middle of the board.
D & E These boards have a single row of TEST points on the front panel. The ballast
lamps are directly behind the TEST points so can easily be seen when on
(when the trunk is off-hook
1
). The revision letter is written along the top edge
of the board.
F & later These boards have a double row of TEST points on the front panel. The
revision letter is written along the top edge of the board.