TM 11-6625-444-14-1
TROUBLESHOOTING AND REPAIR OF PL-1370 / GSM-64B
Section IV.
NOTE
(5) Reconnect the voltmeter to the power
No additional tools and test equipment are
source.
required to troubleshoot and repair the ac
7-14. Performance Check
converter other than those listed in
a. Insure that the malfunction is in the in-
strument and not because of improper operation.
Perform a thorough visual inspection of the ac
The ac converter must be placed on an extender
converter for loose or broken wires, damaged
card to perform troubleshooting procedures.
parts, etc. If no physical damage is noticed, check
a. Remoual,
the performance characteristics of the ac converter.
Refer to table 7-1 and connect the TS-682/GSM - 1
(1) Disconnect the voltmeter from the power
to the INPUT terminals of the voltmeter and apply
source.
t h e listed inputs to the voltmeter for vac
(2) Remove the top cover (2) and the guard
measurement with ac input coupling. Continue
(3) Remove the ac converter from the inner
t r o u b l e s h o o t i n g by performing the voltage
measurements listed in paragraph 7-15.
chassis.
b. A detailed schematic diagram of the ac
b. Replacement.
(1) Align the ac converter with the card
converter is shown in figure FO-12. For parts
location, refer to figure 15, appendix B. Test point
guides at the front and rear card bulkheads.
(2) Plug the ac converter into mating con-
locations are shown on figure 7-1.
nector J13. Be sure that the board edge connector
c. Remove the ac converter from the voltmeter
and mating connector are fully engaged.
(3) Be sure that the cable assembly from the
place. Connect the ac converter to the extender
ac converter is routed properly and the rubber
card. Be sure that all connections are tight.
grommet is in place.
Reconnect the voltmeter to the power source.
(4) Secure the guard and top covers in place.
Perform the required measurements.
Table 7-1. Performance Checks
extender card and insert the ac converter into the
Applicable dc voltages for the ac converter check-
a. Test Point Voltage Measurements. Perform
points are listed in tables 7-2, 7-3, and 7-4. The ac
the voltage measurements listed in table 7-2. Use
converter must be placed on the extender card to
the AN /USM -98 (differential voltmeter) and set
make these tests. Remove the ac converter from
the AN/GSM-64B as follows:
the voltmeter by following the directions given in
(1) Place the shorting bar across the INPUT
terminals.
place and connect the ac converter to the extender
(2) RANGE switch to 1.
card. Be sure that all connections are secure. When
(3) FUNCTION switch to FILTER.
measurements have been completed, remove the
Change 1
