Specifications

(3)
(4)
(5)
(6)
Adjust the TS-382F/U frequency to
100 cps while maintaining an ME-
30 B/U indication of 50 mv. A nor-
mal indication should be +1.5 volts
dc ±0.4.
Adjust the TS-382F/U frequency to
3,000 cps while maintaining an ME-
30 B/U indication of 50 mv. A nor-
mal indication should be +3.0 volts
dc ±0.4.
If the indications obtained in (3) and
(4) above are normal, trouble iso-
lation is complete.
If the indications obtained in (3) or
(4) above are low, proceed to d
below.
d. Isolation.
(1)
(2)
Adjust the TS-382F/U for a fre-
quency of 1,000 cps at a level of
160 mv as indicated on the ME-
30B/U.
Measure the listed signal and dc
voltages given in the chart below to
isolate the faulty part. Measure the
ac voltages with an ME-30B/U;
measure the dc voltages with an
ME -26B/U.
(a) Signal voltage chart.
(5)
Circuit junction
I
Signal Voltage (rms)
P7401-M
Q7401 base
Q7401 emitter
Q7402 base
Q7402 collector
Q7403 base
160 mv
160 mv
160 mv
10 mv
2.5 v
9 mv
(b) DC voltage chart.
Circuit junction
I
+dc voltage to
ground (Volts)
P7401-H
Q7401 base
Q7401 emitter
Q7402 base
Q7402 collector
Q7403 base
Q7403 emitter
P7401-K
16
8.95
8.4
13.8
6.0
14.0
14.1
2.0 (rectified
signal)
56. Isolating Troubles in Assembly A7500
Refer to figure 39 for circuit details and
figure 30 for test point and parts location.
a. Checking Inductor L7501, Potenti-
ometer R7501, and Capacitor C7503.
(1) Remove assembly A7500 from the
TS-1777/VRM-l.
(2) Check the continuity of inductor
L7501, potentiometer R750.1, and
capacitor C7501 to locate the faulty
part.
b. Filter FL7501 Insertion Loss.
(1)
(2)
(3)
(4)
Connect a 50-ohm ±5-percent, 1-
watt, composition resistor between
connector P7501-C and P7501-D.
Connect Hf Signal Generator output
terminals
and the input terminals
of Wide Band Amplifier 460AR and
Rf Millivoltmeter 411A between
connector P7501-M and P7501-L.
Connect the AN/USM-26 to the
460AR.
Adjust the 606A output frequency to
5.65 mc ±100 cps as indicated on
the AN/USM-26 for a 0-db indica-
tion on the 411A.
Move the 411A to connector P7501-
C and P7501-D, and record the db
indication. A normal indication
noted should be an insertion loss
of 6 db or less.
(a) If the indication obtained exceeds
the 6-db insertion loss, replace
filter FL7501.
(b) If the indication is normal, pro-
ceed to c below.
c. Filter FL7501 Bandwidth.
(3)
(4)
(5)
Remove the test signal and set the
TS-1777/VRM-1 ON-OFF switch
to OFF.
Replace the faulty part.
Repeat b and c above.
(4)
(1) Per for m the procedures given
(2)
(3)
in b(l) through (3) above.
-
Adjust the 606A output frequency
to 5.6555 mc to ±100 cps as indi-
cated by the AN/USM-26 and for
a 0-db indication on the 411A.
Move the 411A to connector P7501-
C and P7501-D. The normal in-
dication should be less than 6 db
down.
Move the 411A to connector P7501-
M and P5701-L and adjust the 606A
frequency to 5.6554 mc ±100 cps as
indicated by the AN/USM-26 and
for a 0-db indication on the 411A.
57