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Page Title:
Power Distribution Circuits and Components-continued |
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|  TM 11-5820-509-35
Item
Indication
Probable trouble
Procedure
5
Dc voltage measured between
Low-voltage power supply, filter,
Perform isolation procedures on
A5J7 (fig. 3-4) and chassis
or voltage regulator defective.
PP-3518/PRC-47 (see para 3-6).
ground is not +24 volts dc.
6
No receive audio output or low
a.
+24-volt circuit between J1-19
a.
Check continuity from J1-19 to
and distorted output from
and J2-9 defective.
J2-9: repair open circuit.
headset.
b. Repair or replace AM-
3506/PRC.47 defective.
3506/PRC-47 (para 3-6).
st
7
Dc plate and Wren voltage at 1 -
a. +24-volt circuit between J1-19
and 2d- rf amplifiers in signal
and J5-5 defective.
K3-6: from K3-6 to K3-4; from
data translator not present.
K3-4 to L5: and from L5 to J5-
5.
Check resistance of L5 (normal
72.0 ohms): repair circuit or
replace K3 or L5 if required.
b.
Signal Data Translator CV-
b. Repair or replace CV-
1377A/PRC-47 (A3) defective.
1377A/PRC-47 (para 3-6).
8
Dc voltage measured between
Low-voltage power supply, filter,
Perform isolation procedures on
A5J8 (fig. 3-4) and chassis
or voltage regulator defective.
PP-3518/PRC-47 (A5) (para 3-6)
ground is not +20 volts dc
or replace power supply.
regulated.
9
20 volts dc is not present at
a.
Fuse F3 ( A) (fig. 3-5) is
a.
Check and replace fuse F3.
receiver circuits.
burned out.
b.
20-volt circuit from power
b.
Check continuity from F3 to
supply A5 to receiver circuits is
each circuit: (J2-13, J4-3, J5-3,
defective.
J8-1, J9-1, J11-1, K3-8, K3-2,
L1, and J5-1). L1 resistance is
1.2 ohms. Repair circuit or
replace K3 or L1 if defective.
10
Dc plate and screen voltage at V3
a.
Fuse F5 (1/10A) (fig. 3-5) is
a.
Check F5 and replace fuse.
not present.
burned out.
b.
300-volt circuit between J1-21
b.
Check continuity from J1-21 to
and J7-2 or KC3-7 defective.
F5, from F5 to J7-2 and to R8.
(R8 normal 4,750 ohms). Check
continuity from R8 to K3-7.
Repair circuit or replace R8 if
defective.
11
Filaments of rf amplifiers V1 and
a.
Filament circuit of vacuum
a.
Check filament circuit in each
V2, and driver V3 in signal data
tube(s) open.
tube for continuity. Replace
translator A3 do not light.
defective vacuum tube.
b.
Filament winding of high-
b.
Voltage test-Measure at A5J3
voltage transformer A5T2
to A5J4 with 115-volt ac
defective.
primary power input; normal 6.3
vac rms. (with 26.5 volt dc
primary power input, reading
from A5J3 to J5-4 is 6.3 vac
peak. Replace T2 if winding
defective.
c.
Filament circuit between J1-5
c.
Check continuity from J1-5 to
and T3-1, or J1-4 (or J1-8) and
T3-1 and to FL2-1: from J1-4 to
T3-2 and relay K2 is defective.
K2-2, to K2-8, to T3-2, and
FL2-2 for open circuits or short
to ground. Repair circuit, or
replace relay K2 if defective.
Check continuity from J1-8 to
K2-3 and repair if required.
d.
Filament transformer T3
d.
Check resistance of primary
defective.
(normal 0.75 ohms) and
secondary (normal 0.75 ohms).
Replace if defective. Check
continuity from T3 secondary to
J7-3 and J7-4. Repair if open.
e.
Signal data translator A3
e.
Repair or replace CV-
defective.
1377A/PRC-47 (para 3-6),
3-78
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