AR 10052412, Operating And Service Manual

Page: 68 / 80

Model 5000A225C
44 Rev A
4.3 TROUBLESHOOTING
CAUTION:
The transistors used in the Model 5000A225C amplifier are LDMOS
transistors. These devices are very reliable when installed in a suitable
circuit, but they can be easily damaged by improper troubleshooting or
handling techniques.
Use caution when troubleshooting the LDMOS; do not short the gate to
the ground or to the drain.
CAUTION:
Use care when unpacking new LDMOS. The LDMOS packaging should
only be opened at Electrostatic Discharge (ESD)-approved workstations,
by individuals who are familiar with the handling of LDMOS and other
ESD-sensitive devices.
Troubleshooting the Model 5000A225C in a logical manner can speed the solution to a problem. The settings
of potentiometers (pots), capacitors (caps), or other variables should not be disturbed until other problems have
been eliminated. Comparing the measured DC voltages to those shown on the schematics can solve many
problems. Before measuring circuit voltages, first verify that the voltages to the circuits are correct.
Model 5000A225C troubleshooting symptoms and remedies are described in the sections that follow
• 4.3.1—General: Reading Faults
• 4.3.2—The Unit Cannot be Operated Remotely
•
4.3.3—Thermal Fault
•
4.3.4—Interlock Fault
•
4.3.5—Power Supply Faults
• 4.3.6—Amplifier Faults
• 4.3.7—ALC Fault
• 4.3.8—Low or No Power Output (DC Tests)
•
4.3.9—Low or No Power Output (RF Test)