3 ) T r o u b l e s h o o t i n g chart. The trou-
loose connections; move the wires
and the components gently with an
b l e symptoms listed in the chart
(para 9) will aid in localizing trou-
insulated tool. This m a y s h o w
ble to a component part.
where a faulty connection or com-
(4) Intermittent troubles. In all these
ponent is located.
tests, the possibility of intermit-
6. Test Equipment Required
tent troubles should not be over-
looked. If present, this type of
trouble often may be made to ap-
The following chart lists the test equip-
p e a r by tapping or jarring the
ment required for troubleshooting the rf
equipment. It is possible that some
amplifier. The chart also lists the asso-
e x t e r n a l connections may cause
ciated technical manuals and the common
the trouble. Check the wiring for
names.
Common name
Technical manual
Test equipment
Audio Oscillator TS-382A/U
Audio oscillator
TM 11-2684A
TM 11-6625-203-12,-35
Multimeter AN/URM-105
Voltmeter, Meter ME30A/U
TM 11-6625-320-12
Vtvm
Test Set, Electron Tube TV-2/U
Tube tester
TM 11-2661
Tube tester
Test Set, Electron Tube TV-7/U
TM 11-6625-274-12,-35
Tool Equipment T E- 113
Section II. TROUBLESHOOTING AMPLIFIER, RADIO FREQUENCY AM-1881/11
occur in electron tubes and electrolytic
7. Checking Filament and B Circuits for
Shorts
filter capacitors than in other parts; check
these parts first. If a tube, a resistor, or
a. When to Check. Check the rf am-
a transformer overheats without blowing
plifier for shorts whenever application of
the fuse, check the tubes in the tube tester
line power causes the fuse to burn out or
for shorts.
causes the transformer or other parts to
c. Conditions for Tests. P r e p a r e f o r
overheat.
the short-circuit tests as follows:
b. What to Check. If fuse F1 blows, re-
(1) Remove the top panel on the rf
move V5 and again attempt operation. If
amplifier.
the fuse no longer blows, the trouble is
( 2 ) Remove all tubes and indicator
l o c a t e d in the circuits that follow the
lamp DS1. Mark V1, V2, and V3
r e g u l a t e d power supply. If a replace-
s o that they can be returned to
ment fuse blows with V5 removed, the
their original tube sockets.
trouble is located in the circuits of the
p o w e r transformer and the power rec-
tifier. Replace V5 and remove V4. If a
measurements indicated in the following
replacement fuse still blows, the trouble
chart. If abnormal results are obtained,
i s in power transformer T1, DS1, CR1
make the additional isolating checks out-
or the filament circuits. If the fuse does
lined. When the faulty part is found, re-
not blow, the trouble is in V5, C8A, or
pair the trouble before applying power to
C 8 B . Short circuits are more likely to
the unit.
8
