TM 11-6625-847-45
Item
No.
Indication
Probable trouble
Procedure
c. If the ME-26 (*)/U indicates
+ 4.8 dc in b above
connect the ME-2(*)/U
between the emitter of
transistor A1Q2 and sound
end check for an indication
Of +11.5 volts dc Then
connect the ME-26(*)/U
between the base of tran-
sistor A12 and ground,
and check for an indication
of +11.5 volts dc
If either indication is not
approximately +11.5 volts
dc, check Zener diode
A1VR1 transistor A1Q2,
diode A1CR1, and resistor
A122 for defects. Replace
defective parts
d. If the ME-26(*)/U indicates
+11.5 volt, dc in a above,
on the ME-26(*)/U
between the collector of
transistor A1Q1 and ground
and check for an indication
of +20 volts dc. If indication
is not approximately
+20 volts dc, check tran-
sistor A capacitor A1Q1
A1C2, and resistor A1LR
for defects. Replace defec-
tive parts.
3
Wave analyzer indication
Defective filtering capacitors
Check capacitors A1C5, A1C1,
for 20 volt dc regulator-
and A1C2 for defects. Replace
output in not -45
defective parts
db below the value
recorded when the wave
analyzer in connected
to +27-volt d regulator
input (analyzer
tuned to 120 cps).
4
Converter output(+125
a. Defective dc-to dc converter
a Connect the ME-26(*)/U
volt. dc, 33 volts
switch +17V filter circuit
between terminal A2E8
dc, and +8.3 volts )
in A2.
and ground, mod check for
are not indicated by
an indication of +27 volts
the ME-26(*)U
de. If indication is substan-
when TEST SELEC-
tially below +27 volts dc
TOR switch is at to
or if no indication Is observed,
position. 3, 4, and 5,
check capacitors A2C1
respectively.
through A2C4, resistor A2R1,
inductor U, and diode
A2CR1 for defective. Replace
detective peat.
b.
b. Defective dc-dc converter
b. If +27 volts dc is indicated
switch (transistor Q1 and
at A2E8 in a
Q2)
above, connect the AN/
USM-140 between terminal
9 of transformer T1
2-8
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