Broadcast Electronics FX-50, Instruction Manual, Page: 38 / 189

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©2011 Broadcast Electronics
5.3.1 ADJUSTMENTS.
Adjustment procedures for all controls on all circuit boards are provided by each applicable assembly
publication in Part II of this manual.
5.4 TROUBLESHOOTING.
Most troubleshooting consists of visual checks. The various exciter indicators (meters, LED's, and fuses) should
be observed to isolate the malfunction to a specific area as listed below. Typical meter indications are presented
in Table 5-1 and exciter power demand requirements are listed in Table 5-2.
A. Exciter Input
B. Power Supply Circuit
C. Metering Circuit
D. Modulated Oscillator Circuit
E. AFC/PLL Circuit
F. RF Amplifier
G. Control Circuit
H. Exciter Output
DC VOLTMETER. The FX-50/E is equipped with a high impedance voltmeter which can be employed to measure
internal dc potentials. To convert the front-panel multimeter to a dc test instrument, refer to Figure 5-1 and the
following procedure.
Procedure. To convert the multimeter to a test instrument, proceed as follows:
A. Extend the exciter forward and remove the top-cover.
WARNING DO NOT TOUCH ANY FEED THROUGH CAPACITORS
OR COMPONENTS ON THE RF AMPLIFIER MODULE
WARNING WITH POWER APPLIED.
B. Operate the test switch/indicator on the metering circuit board assembly to illuminate the
switch/indicator. All multimeter function indicators will extinguish and the LCD display will indicate zero
volts.
C. To restore normal operation of the meter, depress any front-panel multimeter function switch. Replace
the top-cover.
Once the trouble is isolated, refer to the applicable section discussing the theory of operation and providing
troubleshooting for the respective assembly to assist in problem resolution. All internal components may be
accessed through a removable top cover (refer to Figure 5-1).
Table 5-1. TYPICAL METER INDICATIONS
MULTIMETER SWITCH
POSITION
MULTIMETER INDICATION
TEST
+20 V +19 to +21 V DC
- 20 V - 19 to -21 V DC
+5 V +4.8 to +5.2 V DC