502-3000 Series Ztron
TM
Point Level Control
Troubleshooting
30
5.4 Testing the
Coaxial Cable
NOTE
Water or other conductive material in the con-
duit can change the electrical properties of the
coax cable and cause the system to perform
poorly. Moisture in the conduit may not be
detected by the following test. Inspect the coax
and associated conduit for trapped water.
a.
Disconnect all three spade lugs of the coaxial cable at
the electronic unit.
b.
Disconnect all three spade lugs of the coaxial cable at
the sensing element.
c.
Check for short circuits. Using an ohmmeter, measure
between two of the coaxial cable conductors. Repeat for
all three conductors. All readings should show an open
circuit, (infinite resistance).
If resistance is measured, the coax cable insulation is
punctured or damaged.
d.
Check for continuity of each conductor. Short out
two of the coaxial cable conductors. Using an ohm-
meter, measure between two of the coaxial cable con-
ductors. Repeat for all three conductors. All readings
should show less <1 ohm resistance.
If no continuity is measured, check for corroded spade
lug connections. Try reterminating spade lugs. Coax is
defective if continuity is still not measured.
NO CONNECTION
OHMMETER
CENTER - GROUND
CENTER - SHIELD
SHIELD - GROUND
OHMS
OHMS
OHMS
CORRECT READING = OPEN CIRCUIT
CHECK FOR SHORTS
8
0
8
8
8
SHORT OUT
TWO CONDUCTORS
CENTER - GROUND
CENTER - SHIELD
SHIELD - GROUND
OHMS
OHMS
OHMS
SHORTED WIRES SHOULD READ 0 OHMS
CHECK FOR CONTINUITY
8
0
"0"
"0"
"0"
OHMMETER
