FM Systems VLS771-2 User manual

VLS771-2
VIDEO LOSS SWITCHER
INSTALLATION MANUAL
IB 628201

VLS771-2
VIDEO LOSS SWITCHER
DESCRIPTION
The VLS771-2 VIDEO LOSS SWITCHER is an automatic 2X1 Stereo
audio follow video switching system that reacts to the loss of
Horizontal Sync pulses. This device monitors the Primary video
source and switches both video and Left and Right Stereo balanced
audio sources to the secondary when the primary video signal
ceases. The unit switches back to the primary channel when the
video returns. This system uses (PLL) Phase-Lock-Loop technology
to prevent false triggering due to high noise video signals. Use
this unit on video from satellite receivers or microwave systems
that exhibit high noise when video fails. If a power failure
occurs the unit will automatically switch to the Primary video and
audio.
The unit can be used to engage a hot standby source or to put
up a test pattern when main video fails. This system will maintain
your video and stereo audio integrity and reduce trouble calls. It
can also be used where unattended video switching must occur.
FEATURES
Features of the VLS771 include a front panel three position
command switch which is used to manually force either primary (A),
secondary (B), or automatic video and audio switching.
Also included are Presents of video front panel LEDs which
indicates the status of the video on the primary and secondary
channel. A Green LED indicates (A channel on), a Red LED indicates
(B channel on).
Standard BNC connectors are used for the video inputs and
output, and a plug-in style removable screw terminal connector is
used for the balanced stereo audio inputs and outputs. This audio
plug can be pre-wired to reduce your installation time.
This switcher is housed in a sturdy aluminum die cast box
which is completely RF shielded. The box can be mounted in the
front or rear of your rack with the standard mounting bracket. An
optional 19" mounting bracket is available. The ordering part
number is PMS700-5A. It holds 5 units and has a common wall mount
power supply to power all 5 units.
VLS771-2.ISB PAGE 2 OF 5

SET-UP AND INSTALLATION
Remove the equipment from the packing materials. The
following materials should be supplied with each order.
QTY 1 VLS771 (Blue Box).
QTY 1Power Cube +24 VDC.
QTY 1 12 Position Plug Audio Connector (may be attached).
QTY 1Rack Mount Angle Bracket (may be attached) or PMS7005A.
SET-UP AND INSTALLATION (continued)
Locate a convenient place in your rack and mount the unit
using the handy Rack Mount Angle Bracket. Next attach the Primary
video signal to the input BNC connector labeled (A INPUT). Then
attach the Secondary video signal to the BNC connector labeled
(B INPUT). The BNC connector labeled (COM OUTPUT) is the output of
the video switch. The video that is selected either manually or
automatically will appear at this connector.
The 12 position snap in audio connector is numbered from left
to right, 1 to 12. The following is a table of the connections
used to switch Balanced audio from Primary to Secondary input.
This audio switch is accomplished by internal relay switching. In
the event of power loss the audio is switched to the Primary
audio.
1. A input Left Tip or +
2. A input Left Ring or -
3. COMM output Left Tip or +
4. COMM output Left Ring or -
5. B input Left Tip or +
6. B input Left Ring or -
7. B input Right Tip or +
8. B input Right Ring or -
9. COMM output Right Tip or +
10. COMM output Right Ring or -
11. A input Right Tip or +
12. A input Right Ring or -
VLS771-2.ISB PAGE 3 OF 5

CONNECTOR BLOCK DIAGRAM
1 2 3 4 5 6 7 8 9 10 11 12
T R T R T R T R T R T R
A OUT B B OUT A
LEFT INPUT RIGHT INPUT
When audio wiring is complete Plug in the power cube and
attach the +24 VDC connector into the VLS771-2.
OPERATION
With video present on the Primary channel (A) the green VIDEO
ON LED will be lit on the front of the unit. This indicates that
video is present at the Primary input. On the front panel there is
a Three Position LOCKING SWITCH, to move this switch it is
necessary to PULL OUT THE HANDLE OF THE SWITCH before trying to
change its position. DO NOT FORCE THE SWITCH. There are three
command modes for the switch. The first is (A) this will cause the
VLS771-2 to manually force the video and audio switch to the A
input source. The second is (B) this will cause a manual switch to
input B. The third position is (AUTO) which stands for AUTOMATIC,
this will automatically switch the video from A to B when the
video on A disappears and will switch back when the video
reappears. In all modes of operation the audio switches with the
video. If mono is to be switched the extra unused contacts of the
VLS771-2 can be used to activate external alarms.
MAINTENANCE
There are no adjustments or calibration required with the
VLS771-2.
VLS771-2 PAGE 4 OF 5

SPECIFICATIONS
VIDEO SPECIFICATION
Standard NTSC or PAL (Auto-Select)
Level (Composite Video) 0.7 to 2 Vp-p (1.0 Vp-p STD.)
Frequency Response > 0.2 dB from DC to 40MHz
Cross-Talk (Pri/Sec input) < 75 dB
Signal to Noise Ratio < 90 dB
Frequency Response Flat from Dc to 50KHz
Cross-Talk (Pri/Sec) < 80 dB
Cross-Talk (Left/Right) < 80 dB
Signal to noise ratio < 90 dB
Power requirement 24 VDC Power Cube (included)
Video Mode Switch 3 Position Locking Toggle
Enclosure 3.5 x 4.5 x 1.5 Die Cast Alm.
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