ADVANCED TROUBLESHOOTING
34.
J) THE RADIO DOESN'T KEY
1. Check the affected headset location for faulty connections or components.
See “Troubleshooting a Headset Location” (page 30).
2. Verifyproperconnectionofradiointerfacepins3&4.
3. Try swapping the Intercom Unit with a known good one (if one is available). If
the problem persists, the problem is in the radio or the Mobile Radio Interface
wiring.
4. If no fault can be found, then the fault must lie in the Intercom Unit. Contact
Firecom for a Return Materials Authorization (RMA) Number to return the
Intercom Unit for repair.
K) ALTERNATOR AND/OR STROBE NOISE IS PRESENT IN TRANSMIT
AUDIO ONLY
1. Verify that the radio interface pins1&2areconnectedproperlyandthatall
connections are clean and tight.
2. Check adjustment of the Transmit Audio. See “Intercom Adjustments” (page 17).
Too much gain here will cause excessive background noise to be transmitted along
with the voice. In the worst case, the voice will be somewhat distorted when trans-
mitting from a quiet place, and will become unintelligible in the presence of back
ground noise.
3. Using a voltmeter, measure the incoming power to the intercom, looking for an
AC signal. There should be less than 300 mV AC present on the power lines.
L) ALTERNATOR AND/OR STROBE NOISE IS PRESENT IN ALL
INTERCOM AUDIO
1. Check for proper positioning of the mic in relation to the speaker’s mouth. See
“Microphone Placement” (page 24). Improper mic positioning will defeat the
noise canceling characteristics of the mics.
2. Inspect the headset microphones, making sure that all slots on both sides of the
mic are clean and unobstructed. Obstruction of these slots will hamper or defeat
the noise canceling characteristics of the mics.
3. Disconnect any exterior headset locations. If the noise stops, inspect that location
for water or other contamination. If contamination is present, contact Firecom for
a Return Materials Authorization (RMA) Number for repair of the unit.
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