Lighting Controls Blue Box LT Series Installation, Operation & Maintenance Manual page 101

THE BLUE BOX LT SYSTEM START-UP & CABLING GUIDE
HARDWARE ACTIvATION TROUBLESHOOTING
!
Always re-check "failed" results . If improperly set or
connected a meter can display unusual readings .
!
The "Bus-Splitting Technique" is the fastest way to find
a bad cable and/or damaged device . Be sure to docu-
ment the cable path!
!
Cat . 5 cables that pass a LAN cable test can still short
or break from stress and strain during installation .
If re-testing a suspected cable, roughly wiggle and tug the
conductors near the RJ45 while keeping an eye on the
LAN tester: conductors should remain properly engaged
throughout the test .
CONTINUITY TEST TROUBLE SHOOTING
1 . Fluctuating resistance readings indicate one or more
"active" devices are still "hot" . De-power all devices
and re-test .
2 . High resistance readings indicate broken or resis-
tive connections . Use the "Bus-splitting" technique to
find:
• RJ45 connectors not properly pushed into sockets
(check to make sure that the wires are not ex-
tended beyond the end of the RJ45 connector)
• Cable strain can break conductors or pull conduc-
tors out of RJ45 contacts (visually inspect cable
and connector) .
• Unseated RJ45 sockets (rough install
ment)
• Damaged device (rare)
• Dirt or paint on RJ45s (rare)
• Bad data/power jumper cable (rare)
SHORT CIRCUIT TEST TROUBLE SHOOTING
1 . A low resistance reading indicates a crossed or short-
ed pair or (rarely) a damaged device . Cable strain
when pushing switches into a wall can short nicked
conductors . Use the bus splitting technique to find
the bad cable, crimp or device .
2 . Resistance readings below 300
an extra terminator . Use the bus splitting technique
to find the short or extra terminator .
3 . After the problem has been resolved, please com-
plete the "Continuity Test" again .
environ-
Ω
on A-B only indicate
EARTH GROUND TROUBLE SHOOTING
LAN-tested cables can still have a path to earth ground .
1 . An abraded or "folded" cable inside the conduit will
cause a short to earth ground .
2 . Other low voltage or high voltage wires touching any
device on the bus will cause continuity to earth ground
Use the Bus Splitting Technique to locate the problem .
TERMINATOR TROUBLE-SHOOTING
1 . Ensure that the Data/Power Jumper is removed .
2 . Visually inspect both terminators are present and
properly seated on each bus-end device .
ERROR CHECk TROUBLESHOOTING
If the hardware activation tests have just been completed
and the bus is unstable, consider the following causes:
1 . Failure to follow the 568A or 568B color code (or
minimally to use a dedicated pair for the center pins)
will cause the Error Check test to fail . Visually inspect
RJ45 connectors .
2 . Occasionally, the flat-cable connecting the clock to
the master panel can become damaged . Visually in-
spect the Cat . 5 cable – if damaged, replace it with a
new cable .
3 . An external source of EMF (electromagnetic fre-
quency) or RF (radio frequency) interference may
be present and affecting the bus (or digital de-
vices) . Refer to the beginning of this guide on run-
ning low voltage cables across or parallel to line
voltage cables or exposing low voltage cables to
EMF or RF sources (e . g . welders, ballasts, improp-
erly grounded wireless devices, etc . ) ; any of which
can interfere with the bus operation and stability .
Visually inspect and handle any external sources of
signal noise - a digital device can also become dam-
aged and create signal noise .
An oscilloscope can be used to locate the source of the
bus failure . The "Oscilloscope Test" can be found in The
Blue Box LT "O&M Manual" .
If unfamiliar with how to use an oscilloscope or if one is
unavailable on-site, contact Tech Support: 1-800-345-4448 .
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