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Section V
Paragraphs 5-30 to 5-37
Model 415E
5-33. MAINTENANCE
OF OPTIONS
01
AND
02.
5-34. Operating instructions for Model 415E instru¬
ments with Option
01
(internally installed battery) and/
or Option 02 (rear panel input connector) is found in
section
in.
Paragraphs
1-6
explain what is covered
by
these
two
options.
Installation and removal
instructions are given in the appendix at the rear of
this manual.
5-35, TROUBLESHOOTING.
5-36. LOCATING TROUBLE.
5-37. Always start locating trouble with a thorough
visual inspection for burned-out or loose components,
loose connections, or any -conditions which suggest a
source of trouble. Check the fuse to see that it is not
open.
5-38. If trouble cannot be isolated to a bad component
by visual inspection, the trouble should be isolated to
a circuit section. Isolation to a circuit section can be
accomplished by using the waveforms (Figures 5-5
through 5-8) and using the front panel performance
tests (Table 5-2).
5-39. POWER SUPPLY TROUBLE.
5-40. Correct operation of the power supply is vital
to"proper operation of the SWR Meter. Noise or vari¬
ation in the regulated voltages causes erratic instru-
Figure 5-3A. Switch Component Location
ment operation. Noise or variation in the offset current
supply causes erratic operation when the 415E is used
for expanded operation (i.e., EXPAND control set to
any position other than NORM). Refer to Paragraph
4- 25 for a discussion of power supply operation.
5- 41. COMPONENT TROUBLE ISOLATION.
5-42. The following procedures and data are given to
aid in determining whether a transistor is operational.
Tests are given for both in-circuit and out-of-circuit
transistors and should be useful in determining whether
a particular section trouble is due to a faulty transistor
or an associated component.
5-43. IN-CIRCUIT TESTING.
5-44. The common causes of transistor failures are
internal short- and open-circuits. In transistor cir¬
cuit testing the most important consideration is the
transistor base - emitter junction. Like the control
grid of a vacuum tube, this is the operational control
point in the transistor. This junction is essentially a
solid-state diode.
For the transistor to conduct, the
diode must conduct; that is, the diode must be forward
biased.
As with simple diodes, the forward-bias po¬
larity is determined by the materials forming the junc-
415 E - A -2 2
Figure 5-3B. Switch Component Location
02152-2
5-10
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