TM 5-6675-250-20
2 - 1 0 . T R O U B L E S H O O T I N G ( C o n t i n u e d)
Table 2-3. Troubleshooting (Continued)
M A L F U N C T I O N
TEST OR INSPECTION
CORRECTIVE ACTION
Step 2. Check for defective GRU.
GYROSCOPIC REFERENCE UNIT (GRU) (Continued)
k. Align the theodolite horizontal circle to the reference mirror.
a. Replace existing GRU with one that is operable. If the system
operates correctly with new GRU, this indicates original GRU was defec-
tive.
b. Replace a defective GRU (1) with a new one, by placing Mode Select
Switch (2) in PWR OFF position (3) and disconnecting and connecting
p o w e r c a b l e ( 4 ) t o t h e G R U ( 1 ).
c. Report defective GRU to Direct Support M a i n t e n a n c e.
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