190-01007-01
GTN 725/750 Maintenance Manual
Rev. 5
Page 4-10
Table 4-9 Operational Checks
Problem
Possible Cause
Corrective Action
With power applied,
GTN does not
respond to input
from one or more of
the following:
• Touchscreen
• Audio volume
knob
•
HOME
key
•
DIRECT-TO
key
• Dual concentric
knobs.
Display head circuitry
malfunctioning.
Replace the GTN. Refer to section 5.1 for details.
OBS indication on
GTN does not
agree with OBS
setting.
GTN resolver or resolver
input not calibrated.
• Calibrate the GTN resolver input.
• If the problem persists, replace the GTN.
Refer to section 5.1 for details.
