Philips LTC2272/50 Installation Instructions Manual page 10

Video Loss
This unit has the ability to detect the loss of sync caused by a
cut or disconnected video cable. If the sync is lost for any
camera for which the video loss function is enabled, the video
loss open collector transistor output will be asserted low for 10
seconds, after which it will be +5 volt logic-high. When there is
a video loss, the unit will display the quad video screen format
on the VIDEO OUT monitor; the following information will
be displayed in each quadrant that has a video loss:
The on-screen text VIDLOSS is displayed in the quadrant.
The flashing icon is displayed on both the VIDEO OUT
and QUAD VIDEO OUT monitors.
The FREEZE LED corresponding to the video input under
video loss flashes.
NOTE: If the unit is powered up while there is loss of sync, the
flashing icon will not be visible since the quadrant will become
white and be the same color as the flashing icon.
CAUTION: The following special setups should
only be done by an authorized service center or
installer.
5.2.4 Quad-Sequence Enable
The quad screen will be sequenced with the four full-screen
video inputs with resistor R259 installed. If R259 is removed,
the quad screen will not be included in the sequence. As factory
default, the unit is shipped with R259 installed. The cover must
be removed to access R259. Refer to Cover Removal and DIP
Switch and Resistor Locations - LTC 2276 Series illustrations.
5.2.5 Video Loss Defeat
Internal DIP switch S201 can be used to defeat the video loss
function of the video inputs. The cover must be removed to
access S201. See Cover Removal and DIP Switch and Resistor
Locations - LTC 2276 Series illustrations. This is used if less
than four cameras are to be connected to the unit. The factory
default is video loss enabled for all four video inputs.
When all four cameras are used, all four positions of the S201
should be open (OFF).
When three cameras are used, they should be connected to video
inputs 1-3, and S201 position 1 should be closed (ON) to
defeat the video loss for 1 video input (4).
When two cameras are used, they should be connected to video
inputs 1-2, and S201 position 2 should be closed (ON) to
defeat the video loss for 2 video inputs (3, 4).
When only one camera is used, it should be connected to video
input 1, and S201 position 3 should be closed (ON) to defeat
the video loss for 3 video inputs (2, 3, 4).
When S201 position 4 is closed (ON), the video loss is defeated
for all four video inputs.
IMPORTANT: Only one position of S201 can be closed
(ON) at a time.
1.6