UNCONTROLLED COPY WHEN DOWNLOADED OR PRINTED
ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL SUPPLEMENT 1
Rev.
5
7-3
Apr
15/15
SECTION 3
SERVICING, TROUBLESHOOTING, AND PERIODIC INSPECTIONS
NOTE
Portions of Section 3 originate from Garmin Manual, 190-00734-11,
GTX 330/33 with ADS-B Out System Maintenance Manual. (Copyright
2015 Garmin Ltd or its Subsidiaries. All Rights Reserved.)
3-1. Servicing
A. Performing maintenance on the GTX 330 is limited to identifying, troubleshooting, and
replacing components according to the parts list in Figure 7-1. Replacement and/or
servicing should occur when an item fails to operate only after the authorized maintenance
technician troubleshoots the system.
3-2. Troubleshooting
A. Refer to Table 7-2, Table 7-3 Section 2 of the GTX Maintenance Manual, and the electrical
schematics, Diagram 7-1 through Diagram 7-3, when troubleshooting the GTX 330
installation.
Table 7-2. GTX 330 Transponder Troubleshooting
Symptom Recommended
Action
Transponder will not turn on
Ensure the XPNDR circuit breaker is closed.
Ensure connectors are seated on transponder
and transponder is seated properly in mounting
rack.
Poor transponder performance. Weak
or intermittent radar contact reported
by ATC.
Check and verify integrity of the antenna
installation, ground planes, and coaxial cables.
Check for proper electrical bonding/grounding of
the antenna installation.
Test coaxial cables for insertion loss and VSWR
(voltage standing wave radio).
Loss of, or incorrect altitude reporting
by the transponder
Check and verify the integrity of the transponder-
altitude encoder interface, including wiring and
altitude encoder operation.
Transponder audio too quiet/loud
Verify that the volume setting is at or above the
minimum required setting.
Incorrect Mode S Aircraft Data
Transmitted
Check the configuration mode settings and reset
if necessary.
Transponder will not come out of
standby
Check the transponder select switch for proper
output.
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