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|  Correction
Probable
trouble
Symptom
Step
repair solder connection if open
circuit is suspected. If this does
not remedy trouble, suspect if.
p r e a m p l i f i e r and/or if. amplifier.
Troubleshoot by signal substitution
F a u l t y if. preamplifier circuit
technique (fig. 74). Check V505,
V506, and V507 (fig. 72).
Troubleshoot by signal substitution
Faulty if. amplifier circuit (fig.
technique (para 74). Check V508
76) .
through V512 (fig. 72).
Check each rf tuner as outlined in
Inoperative rf tuner (fig. 73-74).
steps 2 and 3 below.
Check J504 and P504 for secure
Poor or no connection between
Meter indications are present in
2
mechanical and electrical connec-
7 0 0 - 1 , 0 0 0 - m c position of FRE-
output jack J504 of coaxial
tion.
switch S501 and mating plug
QUENCY RANGE-MC switch,
P504 of cable assembly W503.
but can not be obtained in 400-
Check J508 and P508 for secure
Poor or no connection between
7 0 0 - m c position.
mechanical and electrical connec-
jack J508 on 400-700-mc rf
tion. If this does not remedy
tuner (fig. 73) and mating plug
trouble, suspect defect within
P508 of coaxial cable assembly
coaxial switch S501 (fig. 72).
W503.
Replace V503 or V504.
Defective V503 or V504 (A, fig.
73) .
Remove operating power and dis-
Faulty contacts in coaxial switch
connect plug P503 from input jack
S501 (fig. 72).
J502 on coaxial switch. Also dis-
connect P504 from output jack
J504 on coaxial switch. Use ohm-
meter to check for continuity
from coaxial switch jack J502
through jack J504.
Zero resistance eliminates S501
as source of trouble. Infinite
r e s i s t a n c e indicates defective
coaxial switch. Replace defective
component.
Check for 6.3-volt ac source of
Lack of 6.3-volt ac power source
heater power at protruding termi-
in 400-700 mc rf tuner.
nal of feedthru capacitor CP528
check for 6.3-volt ac from each
terminal of L525 to chassis
ground. If this does not remedy
t r o u b l e , disconnect operating
power and check rf coil L525 for
open circuit, Replace L525 if
defective.
Check wire lead from terminal 16
of P501 (fig. 72) to input terminal
of L545 for continuity. Repair or
replace wire lead if open circuit
is ideated.
Check for +105-volt source of power
Lack of 105-volt power source to
to oscillator V504 from protruding
plate circuit of oscillator V504.
terminal of feedthru capacitor
If no voltage is indicated, check
rf choke L519 for open circuit.
I f necessary, repair wire lead
connection from wiper of switch
(front) to terminal 3 of connector
P501 (fig. 72).
Lack of +150-volt power source t o
Check for B+ voltage to rf amplifier
V503 by measuring voltage from
plate circuit of rf amplifier
protruding terminal of feedthru
V503.
capacitor C521 (fig. 73) to chassis
ground. Proper voltage will be
142
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