TM 11-6625-1633-45
Figure 3 -3 . Signal Generator AN/URM-149, rf oscillator
section removed, right side view.
at the specified test point and under the conditions
(2) When maintenance checks and services indi-
specified in paragraph 3-7.
cate that no output is obtained under any condition.
(5) Intermittent troubles. In all tests, the possibil-
(3) When fuses repeatedly blow.
ity of intermittent troubles should not be overlooked. If
b. The conditions for testing are as follows:
present, this type of trouble often may be made to appear
by tapping or jarring the equipment. Make a visual in-
(1) Remove the signal generator from its case by
spection of all wiring and connections to the unit. Test
releasing the two cam locks at the rear of the carrying
the wiring for loose connections by moving wires and
case and the two screws on either side and sliding the
components with an insulated tool.
chassis out of the carrying case by pulling on the panel-
mounted handles.
3-4. Checking Filament and Plate Voltage
Circuits for Shorts
(2) Remove all tubes and indicator lamps.
a. When any of the following conditions exist, check
for short circuits and eliminate the troubles before ap-
CAUTION
plying power to the equipment.
Do not rock or rotate a tube when remov-
(1) When maintenance checks and services indi-
ing it from a socket; pull it straight out
cate that the POWER indicator lamp will not light nor
with a tube puller.
any of the tube filaments are energized when power is
applied to the unit.
3-4
