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|  TM 11-5820-509-35
Item
Indication
Probable trouble
Procedure
10
With CW-FSK/VOICE switch to
High-voltage power supply circuits
Proceed to power distribution
CW-FSK, multitester at J101
of PP-3518/PRC-47 (A5)
circuit checks (para 3-5b).
defective.
volts dc.
11
Multitester with rf probe at an-
Power amplifier circuit defective.
Proceed to transmitter circuit
tenna simulator - not read
checks (para 3-5e ).
30.7 volts rms with CW-
FSK/VOICE switch to CW-
FSK.
3-5. Localizing Teats
b. Power Distribution Circuit Tests. These tests
are divided into two parts: those where 115-volts, 400-
a. General.
The localizing tests isolate the
Hz ac primary power is used, and those where 26.5-
equipment malfunction to a specific circuit on the main
volts dc primary power is used. The remaining circuits
chassis of RT-671/PRC-47, or to a circuit within a plug-
(those unaffected by the type of primary power used)
in module of the equipment. These tests are performed
are listed separately.
after the sectionalizing tests of paragraph 3-4 c, or
organizational-level tests, have determined that the
(1) Primary Power Source 115-volt, 400-Hz.
trouble symptom exists within a given functional area. A
NOTE
chart is provided for each of the following functional
Connect the test equipment for
areas of the equipment: power distribution circuits,
transmitter tests (fig.
3-3) and
receiver circuits, transmitter circuits, and frequency
perform the initial procedures listed
generation circuits. The test conditions and the test
in paragraph 34 b (3).
Unless
equipment connections for each group of tests is
otherwise specified, make all voltage
detailed in its chart. Carefully observe the equipment
measurements between the test
connections and test conditions to assure that the results
point listed and chassis ground.
obtained are in agreement with the test point value
specified.
Item
Indication
Probable trouble
Procedure
NOTE
Plate the POWER-LIGHTS switch on the front of RT-671 /PRC-47 to POWER ON.
1
Ac voltage measured between test
a. Fuse F2 (POWER 5A AC) is
a.
Check and replace fuse F2 (fig.
jacks A5J10 and A5J11 (fig. 3-
blown or 115-volt primary power
3-87) or repair primary power
4) is not 115 volts ac rms.
circuit is defective.
circuit and/or cable.
Note. Do not perform this test if
b. +26.5 volts dc is not present
b.
Check continuity of T2 primary
26.5-volts dc primary power
at coil of ac power control relay
winding from F2 holder to
source is being used to power
K2 (terminal K2-1).
connector P1-L. Replace T2 if
the equipment. Proceed to next
open circuit, or if shorted to
chart.
chassis. Check continuity of
diodes CR3 thru CR6. Replace
any shorted or open diodes.
c.
POWER-LIGHTS switch on
c.
Check continuity of circuit from
front panel, or associated circuit
K2-5 to chassis ground with
defective.
POWER-LIGHTS switch at
POWER ON. Repair circuit or
replace switch.
d.
Ac power control relay K2 coil
d.
Replace relay K2 if winding
defective.
resistance is not 300 30 oh-
ms.
e.
Contacts on dc power control
e.
Check continuity of normally-
relay K1 or circuit from K1 to
closed contacts K1-2 to K1-8;
K2 defective.
replace K1 if open circuit. Check
continuity from Kl-8 Lo K2-4;
repair circuit if open.
f.
Contacts of ac power control
f.
Replace relay K2.
relay K2 are defective.
2
Dc voltage measured between
a.
Ac primary power circuit to
a.
Check continuity of primary
A5J9 (fig. 3-4) and chassis
PP 3518/PRC-47 (A5) is
power circuit between K1-2 and
ground is not +26.5 volts dc.
defective.
connector J1-13. Repair circuit
on main chassis if open circuit.
b.
Low-voltage transformer A5T2,
b.
Check continuity of A5T2
or its associated circuit in PP-
primary between J1-3 and J1-13.
3518/PRC-47 (A5) is defective.
Repair circuit or replace PP-
3518/PRC 47.
3-75
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