Pathway MR Installers Guide - Manual (Page 15)

DMXPathfinder LR Index
14
and transmitter circuits. Next, a DMX tester should be used to either transmit
DMX in place of the control console, or receive DMX in place of the receiving
device(s). Check the receiving device by connecting the DMX tester directly
to it in transmit mode. Then set the tester to receive mode and monitor the
data coming to the DMXPathfinder from the console, by plugging into the
Input Module faceplate XLR with a female-female cable. If this test does not
point to the data source or the receiving device as being the cause of the
problem, there may be a slight incompatibility between them as far as
DMX512 is concerned. However, if the two units had previously worked
together, these tests will point to a problem in the DMX cable installation or in
one of the DMXPathfinder modules.
At this point, the suspect Output Module’s output card or should be withdrawn
from its chassis and the spare unit inserted in its place (remember to power
down before withdrawing or inserting any cards). If this proves that the
original unit is defective, inspect the card for signs of damage or any other
obvious cause. Return the defective card to the factory for repair unless you
have the facilities to carry out your own service. For more serious defects,
such as power supply or fan failure, disconnect the entire module and take it
to the test bench for repair, or return it to the factory. DMXPathfinder MR
modules are not difficult to service with basic tools and test equipment. If the
suspect module proves to be good, test the DMX cable installation for open
or shorted lines using a loopback test connector. You can easily make one of
these from a 5-pin male XLR plug by shorting together pins 2&4 and 3&5.
Insert the plug into the female DMX-out receptacle at the far end of the cable
and apply a DMX signal to the desired DMXPathfinder input. Switch-select
that input at the crosspoint card. If the wiring installation is good, the green &
amber LEDs on the Input Module, crosspoint card and output card will all be
illuminated. Note that this test is possible only in systems where all five XLR
pins are wired.
If the above tests yield passing results and the problem persists, it may be
necessary to use the Fluke LAN Cable Meter to do a high-frequency analysis
of the suspect cable runs. This test will quickly indicate any anomalies
having to do with cable impedance and capacitance that would result in
excessive signal distortion or attenuation. This test will help to locate less-
obvious problems such as pinched or over-heated cabling that cannot be
found with simple continuity checks.