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|  indicated in the Normal indication column,
measurements indicated in the following
make the additional checks outlined under
charts in the Point of measurement col-
Isolating procedure.
umn. If abnormal results are obtained, as
Isolating procedure
Normal Indication
Point of measurement
Filament abort-circuit tests (fig. 37)
Disconnect P2, front panel (para 117),
Approximately 6,000 ohms . . . . .
Terminal E of P1 to ground. . . .
wires from rear plug filters, or
Infinite resistance . . . . . . . . .
Terminal S of P1 to ground . . . .
wires from tie points E1 through E5
Infinite resistance . . . . . . . . .
Terminal T of P1 to ground. . . .
as necessary to isolate trouble to
Infinite resistance . . . . . . . . . . . . . .
Terminal U of P1 to ground . . . .
faulty circuit (fig. 47).
Infinite
resistance
.
.
.
.
.
.
.
.
.
Terminal D of J1 to ground . . . .
Infinite
resistance
.
.
.
.
.
.
.
.
.
Terminal J of J1 to ground . . . .
Note. To reach rear plug filters FL22 through
Infinite
resistance
.
.
.
.
.
.
.
.
.
Terminal H of J8 to ground . . . .
FL25 and FL15, remove rear cover on filters
Infinite
resistance
.
.
.
.
.
.
.
.
.
Terminal K of J8 to ground . . . .
on the cover.
Infinite
resistance
.
.
.
.
.
.
.
.
.
Terminal J of J8 to ground. . . .
Make continuity checks to isolate
Infinite
resistance
.
.
.
.
.
.
.
.
.
P401 (3.0-3.9 mc if. subunit), pin
trouble for each item listed in this
F or C to ground.
chart.
Infinite resistance . . . . . . . . .
P501 (500-kc if. subunit), pins C,
D, and H to ground.
Infinite resistance . . . . . . . . .
P301 (first if.), pins C, D, E, and
J to ground.
Infinite resistance . . . . . . . . .
P201 (uhf injection subunit), pins
C, D, and F to ground.
Infinite resistance . . . . . . . . .
P801 (audio amplifier and modula-
tor subunit), pins C, D, H, J,
and K to ground.
Infinite resistance . . . . . . . . .
P101 (rf end power amplifier sub-
unit), pin J to ground.
Approximately 5 ohms . . . . . . .
Pin B to ground . . . . . . . . . .
Point of measurement
Normal
indications
Isolating
procedure
300V B+ short-circuit test (fig. 23)
Terminal H of P1 . . . . . . . . . . . . . .
30K ohms . . . . . .
If resistance is lower than 30K ohms,
proceed with 300V B+ short-circuit tests.
Terminal H of P1 with P501 disconnected . .
30K ohms . . . . . .
If resistance is now 30K ohms, remove 500-
kc if. amplifier subunit (para 111) and
check plate and screen grid circuit com-
ponents (fig. 59, 60, and 61).
Terminal H of P1 with P501 and P801
570K ohms . . . . .
If resistance is now 570K ohms, remove
disconnected.
audio amplifier and modulator subunit
circuit components (fig. 76, 77, and 78).
Terminal H of P1 with P501, P801, and
570K ohms . . . . .
If resistance is now 570K ohms, remove rf
P101 disconnected.
and power amplifier subunit (para 107) and
check C133 (fig. 69), Z108 (fig. 74), the
plate circuit of V106, plate circuit compo-
nents of V105 (fig. 70).
Terminal H of P1 with P501, P801, P101,
If resistance is now 1 megohm, check relay
1 megohm . . . . .
and relay subunit removed.
subunit capacitors C606 through C609
(fig. 67).
Terminal H of P1 with P501, P801, P101,
Infinite resistance .
If resistance is now infinite, check front
disconnected and relay subunit and front
panel resistors R705 and R707 (fig. 49).
panel removed.
If resistance is not infinite, check
FL13, FL35 (fig. 48), and associated
main frame wiring (fig. 127).
76
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