TM 55-1520-240-T
18-3.2 DOPPLER/GPS NAVIGATION SYSTEM VISUAL CHECK
INITIAL SETUP
Applicable Configurations:
All
Tools:
Electrical Repairer’s Tool Kit,
NSN 5180-00-323-4915
Materials:
None
References:
TM 55-1520-240-23
Equipment Condition:
TM 55-1520-240-23:
Battery Disconnected
Electrical Power Off
No. 2 Access Door (Tunnel Cover)
Open
Personnel Required:
68F10 Aircraft Electrician
TASK
RESULT
1. Check DGNS CDU (1).
2. Check GPS Alert Light Indicator (2).
Loosen Dzus fasteners and check rear connectors of
DGNS CDU (1). If connectors are loose or damaged
tighten or replace it as required. If wiring to connector
is loose or damaged, tighten, repair, or replace it as
required. If display screen is damaged in any way
replace CDU (1). If knobs are loose or broken tighten
or replace as required. If pushbuttons are damaged
replace CDU (1). Reinstall CDU (1) in the canted
console tightening the Dzus fasteners.
If indicator (2) is loose or damaged tighten or replace
as required.
3. Check GPS Zeroize Switch/Cover (3).
4. Check GPS/DOP SEL Indicator (4).
5. Check DOPPLER Circuit Breakers (5).
6. Check RADAR Signal Data Converter
CV-3338A/ASN-128B (SDC) (6).
If switch or cover (3) is loose or damaged tighten or
replace as required. If wiring to switch is loose or
broken tighten, repair, or replace as required.
If indicator lens (4) is damaged replace.
If breakers (5) are loose or damaged tighten or replace
as required. If wiring to breaker is loose or broken
tighten, repair, or replace as required.
If SDC (6) is loose or damaged tighten or replace as
required. If connectors to the SDC are loose or dam-
aged tighten or replace as required. If wiring or cables
to SDC are loose or damaged tighten, repair, or
replace as required.
18-3.2
TASK
RESULT
7. Check GPS Data Loader Receptacle (7).
If receptacle (7) is loose or damaged tighten or replace
as required. If pushbutton is loose or damaged re-
place Data Loader Receptacle. If the connector to the
receptacle is loose or damaged tighten or replace as
required If wiring to the connector is loose or dam-
aged tighten, repair, or replace as required.
8. Check GPS Antenna (8).
If antenna (8) is loose or damaged tighten or replace
as required. If cable (9) to antenna is loose or broken
tighten or replace as required. DO NOT REPAIR
THIS CABLE.
FOLLOW-ON MAINTENANCE:
Close No. 2 Access Door (Tunnel Cover)
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Change 19
18-67
