CHAPTER 2
TROUBLESHOOTING
Section I. GENERAL TROUBLESHOOTING TECHNIQUES
Warning:
1. When servicing the rf amplifier, be careful of high voltages. Potentials in excess
of 300 volts are exposed at various places below the chassis.
2. The rf amplifier contains a selenium rectifier mounted on the top of the chassis.
When selenium rectifiers fail because of burnout or arc-over, poisonous fumes and
compounds are released. The fumes have a strong odor and should not be inhaled.
Provide adequate ventilation immediately and do not handle the rectifier until it has
cooled.
step in tracing trouble is to locate the
4. General Instructions
circuit at fault by the following methods:
Troubleshooting at field and depot main-
(1) Visual inspection. The purpose of
tenance level includes all the techniques
visual inspection is to locate faults
outlined for organizational maintenance
without testing or measuring the
included in TM 11-6625-353-12 and the
c i r c u i t s . All visual signs should
more comprehensive techniques for lo-
be observed and an attempt made
calizing trouble symptoms described in
to sectionalize the fault to a par-
this manual. Together, the two manuals
ticular circuit. A good visual in-
give a complete systematic troubleshooting
s p e c t i o n method is outlined in
procedure, beginning with simple visual
paragraph 20, TM 11-6625-353-12.
inspection and ending with tube socket
(2) O p e r a t i o n a l tests. Operational
voltage, resistance, and stage gain meas-
tests
frequently
indicate
the
u r e m e n t s . Troubleshooting instructions
g e n e r a l location of trouble. In
i n this manual include resistance and
m a n y instances, the tests will
voltage measurements, stage gain meas-
help to determine the exact nature
urements, and possible circuit malfunc-
of the fault.
t i o n s for various incorrect voltage and
c Localization. The tests listed below
resistance readings.
will aid in isolating the trouble. First,
localize the trouble to a single stage or
5. Organization of Troubleshooting Procedures
circuit, and then isolate the trouble within
a. General. The first step in servicing
t h a t circuit by voltage, resistance, and
a defective rf amplifier is to sectionalize
continuity measurements.
the fault. Sectionalization means tracing
(1) Stage-gain measurements. Stage-
the fault to a major component. The sec-
gain measurements (para 10) will
ond step is to localize the fault. Localiza-
help to isolate a trouble to a spe-
tion means tracing the fault to a defective
cific circuit at fault.
part responsible for the abnormal condi-
t i o n . Some faults, such as burned-out
(2) Voltage and resistance measure-
resistors, arcing, and shorted trans-
ments. These measurements will
f o r m e r s can often be located by sight,
help locate the individual faulty
smell, and hearing. The majority of faults,
parts. Use resistor and capacitor
however, must be localized by checking
the voltages and resistance.
the value of the components. Use
the voltage and resistance diagram
b. Sectionalization. The rf ampli-
fier consists of two major sections: an
compare them with the readings
electronically regulated power supply and
taken.
a three-stage amplifier section. The first
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