CONNECTIONS and OPERATION
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Figure 2 - 1421 Rear Panel
CONNECTIONS
Video Inputs
The BNC video input connector located on the back panel is
terminated internally in 75 ohms. Therefore, if a video cable is
looped through a monitor between the camera and the amplifier,
that monitor’s termination switch should be set to HI-Z.
Otherwise, the camera output “sees” a double termination, which
reduces its video signal level.
VIDEO OUTPUTS
The four BNC video outputs are designed to be terminated in a 75-
ohm load. Therefore, if any of the video output cable are looped
through monitors or other accessories, be sure their terminations
are set to HI-Z. Only the last unit on the line should have its
termination set to 75 ohms. All four outputs may be used
simultaneously. Shorts or opens on any one output do not affect
the other outputs. Unused outputs should be left disconnected and
are not terminated.
VIDEO LOSS DETECTION OUTPUT
An open collector pull-down output is available on the rear panel
to signal a loss of video to other equipment. When no video is
present (LED red), the output transistor is on (pulled down). This
output can sink up to 20 ma from external circuits or devices
operating form a maximum of 24 V DC. Multiple 1421s may be
connected in parallel so that a loss of video on any one unit signals
an alert.
External Video Loss 5-Pin Connector
Pin 1 - Common
Pin 2 - Video Loss Output
Caution: Do not apply external voltages to this connector.
Precautions should be taken, especially with multiple amplifiers,
to prevent incorrect connections which may damage the amplifier.
Power Connection
1421 models operate from 120 VAC, 50/60 Hz. 1421/X models
operate from 240 VAC, 50/60 Hz. The operating voltage is shown
on the back panel. A 3-wire power cord and plug are attached.
OPERATION
There are no adjustments or controls on the 1421 Distribution
Amplifier. The video signal connected to its input is reproduced
on each of the four independent outputs.
The front panel LED power and video presence indicator provides
the following information:
LED OFF: No input AC power
LED GREEN: Norman operation – AC power is on and a video
input is present
LED RED: Video loss – AC power is on, but no video input is
present
The LED video presence or loss indicator is not affected by shorts
or opens on any of the four outputs. It indicates the presence of an
input signal and the proper operation of the internal circuits of the
1421.
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