5-22 5.0 TROUBLESHOOTING
4125 SIDE SCAN SONAR SYSTEM 0004823_REV_F
5.7.1 Locating a Shorted Conductor
The presence of a shorted or open conductor in a tow cable can be determined by using a multimeter.
To locate a shorted or open conductor:
1. Disconnect both cable ends.
2. Short the two connector pins (or conductors if un-terminated) of the shorted pair at both ends
and measure the total resistance between the ends.
R1+R2 =_______________
3. Remove the shorts.
4. Measure the resistance between a shorted pair on one end with an ohmmeter on the Rx1 scale.
R1+Rs =_______________
5. Measure the resistance from the other end.
R2+Rs =_______________
6. Add the measurements in Step 4 and 5 above, subtract the measurement in Step 2, and divide
the result by 2.
Rs =_________________
7. Subtract the value in Step 6 from the measurements in Step 4 and 5.
R1 =_________________
R2 =_________________
The distance to the short from end #1 is the ratio of R1/(R1+R2) times the total cable length. Recheck
from end #2 which is R2/(R1+R2) times the cable length.
5.7.2 Locating an Open Conductor
An open conductor in a tow cable is much more difficult to locate than a short. Therefore a capacitance
bridge is recommended to diagnose this problem. Measuring the capacitance from the open conductor
to the shield on both ends allows two different capacitance readings to be recorded. This represents a
direct ratio related to cable length and distance of break from each end.
Before cutting the cable, double-check the same ratio of capacitance using an adjacent good conductor in
a multi-conductor cable. Capacitance may vary from conductor to conductor, depending on their
separation.
Most breaks occur around the tow cable termination, or where a previous repair has been made. A cable
break may be found or confirmed by laying out the cable and then attaching an ohmmeter across each
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