5 Troubleshooting
46
5.4.2 ZBA External Fuse
A ZBA is also a surge suppressor and reduces the chance of damage to the ZBA and PAL-AT from
external voltage spikes, e.g. nearby lightning strikes. A replaceable fast-acting fuse in the fuse holder
terminal provides protection. The replacement 5x20 mm fuse is rated 250 mA, 250 V, fast-acting. It can
be obtained locally or purchase from PermAlert (P/N 8067989).
If the ZBA external fuse fails, PAL-AT displays the message "NO END FOUND" or "FAULT IN FIRST 50
FEET".
5.5 Cable Connector Tests
The following tests are performed on each length of cable after both connectors are installed during
installation. Figure 5-2 illustrates the tests. Any overbraid or outer jacket is not shown. Install the
connectors according to the instructions in the PAL-AT Installation Manual.
Continuity Test
The continuity test checks for broken cable, open connectors, and poor solder connections.
1. Connect a short jumper wire with alligator clips between the UHF connector’s center contact and
the body of the connector at one end of the cable. Note: Do not clip onto the threaded coupling
ring because it is not tightly secured and can give intermittent readings.
2. Connect the ohmmeter's test leads to the connector’s center contact and connector body on the
other end of the cable.
3. The normal ohmmeter reading is less than 10 ohms/1000' [10 ohms/300 m] of cable. If it is not,
check the jumper wire, test lead connections, and repeat the test. If the problem persists, contact
the PermAlert Field Service Department for assistance.
Alternate System Test
1. Connect the entire cable string to the PAL-AT panel.
2. Make sure the panel is turned off. Set the impedance jumper for the cable under test – position C
(w/o ZBA) or D (w/ZBA). If applicable, make sure the replaceable fuse in the ZBP is good.
3. Measure the resistance at the far end of the cable string. Connect one test lead to the center
contact of the last connector and the other lead to the connector body. The resistance should be
less than 60 ohms + 10 ohms/1000' [75 ohms/300 m] of cable string.
Insulation Test
The insulation test checks for a short between the center conductor and outer braid shield.
1. Remove the jumper wire used in the continuity test, and connect one ohmmeter test lead to the
connector's center contact and the other lead to the connector body.
2. A good cable gives a full-scale reading (at least 10 megohms). Test readings below full scale
indicate damaged cable or an improperly installed connector. If the problem persists, contact
PermAlert's Field Service Department for assistance.
Figure 5-2
Cable Tests
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