Leprecon LP-900 - Manual (Page 8)

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Leprecon/CAE, Inc. P.O. Box 430 Hamburg, Michigan 48139 810-231-9373
Leprecon®
Pro Lighting Equipment
REPAIRS AND MAINTENANCE (continued)
The first step in major troubleshooting is to prove the problem is in the board.
With the snake disconnected, if the LEDs function normally from the power
supply to the output indicators and control voltage is verified with a meter at the
output connector, the board by itself is functioning as it should. Snake channels
that are shorted to control common or to another controller will show on the
output LEDs when the snake is plugged in. An LED that jumps to full up when
the slider is moved above minimum, indicates an output shorted to common or
ground. An LED that is off when the fader is partially up can indicate a short
between channels. A comprehensive test for shorts is to bring all outputs full up
and verify with a meter that each channel can be run from maximum to minimum
with the other channels up.
If all LEDs respond normally but no voltage can be read at any of the outputs, the
problem is probably a break in the control common between the power supply
card and the output connector.
The circuit boards in the console are inter-connected by ribbon cables that carry
power and the necessary input and output lines. A defect in one card can affect
everything it is connected to. Faults in a 6XDM can affect the entire scene and a
short to V+ in any card can kill the entire board. Problems are isolated by
removing the ribbon jumpers from suspect modules and then checking the other
modules to see if normal operation is restored.
Modules connected by a continuous ribbon are a functional system. Boards with
an input and an output are connections between systems.
There are three ribbon jumper systems in a board:
Horizontal ribbon jumpers for each scene of 6XDM’s;
These connect to the submaster output, and supply the entire scene.
Vertical jumpers from scene to scene on each 6XDM;
This is 6XDM output/6XEM input jumper.
Submaster input ribbons connecting the scene master output to all
submasters; This ribbon may continue to the grand master and power
supply or those connections may be made through other cables.
The proper function of the power supply, grand master, crossfader, and
submasters can be checked by disconnecting ribbon cables.