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 TM 55-1905-219-14-11
5-117. SHIP'S COURSE INDICATOR - MAINTENANCE INSTRUCTIONS (Continued).
(c)
Check power and synchro voltages 115VAC 400 cycles at the terminal board inside the base of the
indicator housing and verify that these voltages are reaching the internal assembly through the cable that connects to the
terminal board.
(d)
When SCI dial and the synchro data source are at 0 degrees, the following voltages should be
measured.
1
Synchro torque receivers:
S1 - S3,
0
volts a-c
S2 - S3,
78
volts a-c
S1 - S2,
78
volts a-c
R1 - R2,
115
volts a-c
2
Synchro control transformers.
R-1 - R-2,
0
volts a-c
(e)
Use an a-c voltmeter with a sensitivity of 1000 ohms per volt and a full-scale range of 150 rms volts.
Similarly, measure the primary and secondary voltages of power transformer T2 and a lamp transformer T3.
(f)
If these tests do not indicate the proper voltages, then the cause of trouble is in the external wiring or
transmitting equipment. If proper voltages are present, proceed to make the following tests. The indicator may be
repaired at its installed location. A clean area with appropriate power and synchro signals for energizing indicator is
preferred if available.
(5)
Mechanical or electrical trouble.
(a)
No indicator contains a fuse. Fuses in the power circuit to the indicator will be on a switchboard.
(b)
The following table gives several symptoms of trouble. To verify and correct any of these troubles, refer
to the text that follows for more detailed instructions.
5-1314
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