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The “head” display is working, but the next display (Display 2) doesn’t show an image.
1. Make sure that the VGA input has been selected on Display 2.
2. Double-check the local connection:
o Is the VGA Local properly connected to the VGA input on the “head” display? And,
o Is the output of the “head” LT card connected to the next input (either VGA input on
card 2 or VGA input on Display 2)?
3. If after Step 2 there is still no image on Display 2 then swap Display 2 with another display
that has been proven to function properly and re-install card 2.
4. If after Step 3 there is still no image on Display 2 then swap card 2 with a card that has been
proven to function properly. If there is now a visible image on display2 the card is likely
broken
RS232 doesn’t seem to work properly via the LT card.
1. Follow the same steps for troubleshooting RS232 issues as used above for troubleshooting
VGA issues.
Important general remarks
1. The LT card uses amplifiers to amplify the video signals. Electronic amplifiers inherently add
noise to these signals. When looping through the signals there will always be some signal
degradation and the acceptability is a subjective matter. There is a dependency of the quality
of the interconnecting cables that are used so always use high quality cables with ferrites.
2. Long cables and loop through of the RS232 signals influence the effective transmission
bandwidth (signal slopes will be affected). Therefore it is advised to use lower baud rates
when more displays are looped through and longer distances are covered. There are cable
quality dependencies and the system integrator will need to try out which is the optimal baud
rate for the installed network.
How many units can be daisy chained
For VGA the product has been tested up to 5 displays. More units can be daisy chained but some
picture quality degradation may be visible. For RS232 only at least 10 units can be daisy chained.
Maximum distance between signal source and the last daisy chained display
Philips recommends not to exceed 30 meters / 98 feet between the signal source (usually a PC)
and last daisy chained display.
Page 8 of 9 LT Installation Guide 1.1 (140907)
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