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|  Step
Probable
trouble
Correction
Symptom
c o r r e c t trouble, troubleshoot
1,600-kc if. amplifier to localfae
defective stage. Refer to voltage
and resistance diagram (fig. 47)
and parts location diagram (fig.
61) .
Defective electrical part in if.
Check with voltmeter for 150-volt
input selector (fig. 59).
B+ energizing potential at pro-
truding terminal on feedthru
capacitor C79 (input to relay K2
to chassis ground, with band
switch at band 2, 4, 5, or 6. If
no voltage is present, check R24
and coil of K2 for open; also check
C78 and C79 for short. Replace
defective component.
Remove operating power and check
primary and secondary windings
of T23 for open circuit. check
C71 and C77 for short. Replace
defective component.
Defective cable connections to if.
Check for secure electrical contact
step attenuator AT1 (fig. 60).
between connector plug P8 and
mating jack J6 on if. input selec-
connector plug P2 and mating
jack J1 on if. step attenuator AT1
W1 (fig. 56) for continuity; repair
o r replace if necessary.
Defective electrical part in if.
Remove operating power and check
step attenuator AT1 (fig. 60).
for continuity of relays K3, K4,
and K5 (fig. 60) to chassis ground.
Convenient test points are at pro-
truding center terminals of feed-
thru capacitors C85, C86, and
C88. If open circuit is indicated
at any test, suspect R31, R32, or
R38 before replacing relay. If
z e r o resistance is indicated,
suspect shorted C84 or C85 (for
K3), C86 or C87 (for K4), and
C88 or C89 (for K5), before
r e p l a c i n g relay.
Remove operating power; then
remove cover of if. step attenu-
a t o r ATl. Check precision resis-
tors R33 through R37 for open,
short, or out-of-1% tolerance from
values indicated on schematic dia-
gram (fig. 17). Replace cover
a f t e r correcting trouble.
Check for secure connection of con-
Defective cable connections to
Onscale meter indications are ob-
3
455-kc if. amplifier or defec-
nector plug P4 with mating jack J3
served with MEGACYCLES band
on if. step attenuator ATI sub-
tive 455-kc if. amplifier (fig.
switch at band 2 (.36-.87 mc),
62) .
assembly (fig. 56); also check for
band 4 (2.1-5.2 mc), band 5
secure connection of connector
(5.2-12.7 mc), and band 6
plug P6 with mating jack J5 on if.
(12.7-30 mc), but cannot be ob-
tained in bands 1 and 3.
output selector subassembly. If
cable connections do not correct
trouble, troubleshoot 455-kc if.
amplifier to localize defective
stage. Refer to voltage and
resistance diagram (fig. 47) and
parts location diagram (fig. 62).
119
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