Miteq D-9301, Руководство по эксплуатации и обслуживанию, Страница: 53 / 86

5-4
5.3 CORRECTIVE MAINTENANCE
If the converter malfunctions during normal use or if the tests
in Section 5.2 reveal excessive discrepancies in converter gain
or local oscillator frequency or test point voltage, isolation
and correction of the malfunction becomes necessary.
While it is difficult to fully anticipate and describe all
possible failure modes in a complicated electronic system, this
manual contains sufficient information in the form of theory of
operation and diagrams to enable an experienced technician to
isolate and remove the malfunctioning module. In addition, power
supply failures can be corrected on the station level.
5.3.1 POWER SUPPLY MALFUNCTION
If the fault is detected in the power supply, remove the power
supply protective cover. Check AC voltage input to the power
supply. With the help of the power supply schematics in Appendix
A, isolate the malfunctioning component.
5.3.2 LOCAL OSCILLATOR
To isolate the malfunctioning component in the local oscillator
chain, Section 4.3.2 should first be carefully studied for theory
of operation. The following voltage check should be performed
before proceeding.
Check DC voltages to phase lock oscillators. A scope (AC
coupled) should be applied to voltage line to measure power
supply ripple (refer to Appendix for specifications). If
incorrect voltage or excessive ripple is observed, refer to
Paragraph 5.3.1 for a power supply check.
Power level of the input reference should be checked. Required
input reference power level for phase lock sources is 0±3 dBm.
If the reference source is significantly off frequency, the phase
lock source may not be able to lock to it. Frequency of the
reference should be 5.000000 MHz.
Assuming an "in-lock" condition at the correct output frequency,
check output power. If unit is out of specification or above
procedures fail to rectify the problem, it is recommended that
unit be returned for factory repair.
5.3.3 CONVERTER, SIGNAL CHAIN
The components in the signal chain can be checked against the
individual specifications listed in Section 4.3.