TB 43-0149
APPENDIX B
TROUBLESHOOTING, AIRFIELD RUNWAY SETS (Cont'd)
TROUBLE
PROBABLE CAUSE
REMEDY
If the break or open connection is not located by
the above method, each section will have to be
checked. A length of cable known to be good is
used for checking the various lengths of cable in
the circuit. The length of test cable is laid on the
ground and connected into the circuit in place of
each of the cables being checked. Checks
should be made from lamp to lamp as the good,
then the primary leads of the transformers may
be easily disconnected from the lighting circuit
and connected to the length of test cable. The
first sections to be checked should be those
where there is considerable traffic or where
vehicles may have dragged the cable over
rocks, etc. If the section being checked is found
to be good, then the primary leads to the
transformer at one end of the section are
disconnected from the length of test cable and
the adjacent power cable, and the latter two are
connected. If successive cable lengths are
checked, all included transformers can then be
checked. If the system works properly after the
length of test cable and the adjacent power
cables are connected, then the transformer was
faulty and a new one is put in place and
connected. The original power cable section
being checked is reconnected into the circuit. If
the system still does not work then the
transformer and original cable section are
reconnected into the circuit and the next section
of the power cable is checked, and so on.
WARNING
If a test on a circuit component reveals that the
fault lies elsewhere, turn the regulator control
switch to the OFF position before handling the
circuit.
41
