Broadcast Electronics AM-2.5E, Руководство пользователя

Страница: 195 / 320

2-2
WARNING: DISCONNECT POWER PRIOR TO SERVICING
WARNING
WARNING
DISCONNECT ALL TRANSMITTER PRIMARY POWER
BEFORE ATTEMPTING ANY EQUIPMENT MAINTE
NANCE.
2-9. Ensure all transmitter primary power is disconnected and clean the output network
assembly of accumulated dust using a nylon bristle brush and vacuum cleaner. Inspect
the components for damage by overheating and arcing. In addition, check the
components for loose hardware.
2-10.
SECOND LEVEL MAINTENANCE.
2-11. Second level maintenance is the performance of procedures required to restore the ECU to
operation after a fault has occurred. The procedures are divided into electrical
adjustments procedures and troubleshooting.
2-12.
ELECTRICAL ADJUSTMENTS.
2-13.
MODULATION CALIBRATION CONTROLS.
Modulation calibration controls R201
through R205 calibrate the modulation sample for each power level. A complete
description of the procedure to adjust the power level controls is presented in SECTION
II, INSTALLATION. Refer to POWER LEVEL AND MODULATION CALIBRATION
ADJUSTMENT in SECTION II for the adjustment procedure.
2-14.
DIRECTIONAL COUPLER NULL CONTROLS.
Directional coupler null controls R223,
R224, R234, and R235 null the directional coupler sampling circuit. Due to the critical
nature of the directional coupler null controls, the controls are not considered field
adjustable. If the controls are required to be adjusted, contact the Broadcast Electronics
Customer Service Department for information and instructions to adjust the directional
coupler null controls.
2-15.
TROUBLESHOOTING.
WARNING
WARNING
WARNING
WARNING
THE TRANSMITTER CONTAINS MULTIPLE CIRCUIT
GROUNDS WITH HIGH AC AND DC POTENTIALS
WITH RESPECT TO THE CABINET WHICH IS AT
EARTH POTENTIAL. DO NOT ENERGIZE THE
TRANSMITTER WITH TEST EQUIPMENT CON
NECTED TO THE TRANSMITTER OUTPUT
NETWORK, RF POWER MODULE, RF COMBINER, OR
POWER SUPPLY COMPONENTS.
2-16.
SAFETY CONSIDERATIONS.
The AM-2.5E/AM-5E transmitters are equipped with
extensive indicator and meter circuitry to allow the operator to isolate problems to a
specific area within the transmitter. Due to the hazardous voltages and currents
contained in the equipment, operation of the transmitter with test equipment connected
to transmitter output network, RF power module, RF combiner, or power supply
components is extremely dangerous and must not be attempted. Test equipment may be
connected to the ECU circuit boards from the front of the transmitter using the supplied
extender circuit board with power energized. The maintenance procedures presented in
this section should be performed only by trained and experienced maintenance personnel.
2-17.
OUTPUT NETWORK ASSEMBLY COMPONENT LOCATIONS.
Component locations for
the output network assembly are presented in PART I SECTION V, MAINTENANCE.
Refer to TRANSMITTER COMPONENT LOCATIONS in SECTION V to locate
components within the output network assembly.