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T281
Primary
connections
W DTH
CAL
R180
+25 -VOLT SUPPLY
2.
Check +35-volt unregulated supply
a. Change the VOM positive lead to the positive terminal
of C298.
b. Check that the meter reads 4-33 volts 4 2 volts.
Fig. 4-4. + 25 volt supply adjustment.
3.
Check voltage across D209
a. Change the VOM positive lead to the junction of D208,
R2 0 9 and D209.
1 µ sec period
adjust C115F
+25 V OLTS
+35- VOLT SUPPLY
ADJUST
Fig. 4-3, Type 114 chassis, bottom view.
b. Check that the meter reads + 3 volts ±½ volt from
the j unction to chassis ground.
4. Check + 25-volt supply regulation
a. Change the VOM positive lead to the outside shell of
C298. Chock that the meter reads +2 5 volts
b. Using the variable line voltage source, vary the line
volt age from 94.5 to 137.5 volts.
c. Check that the VOM reading does not change more
than 0.5 v while the line voltage is varied over the range
specified.
d. Return the variable line voltage source to 115 volts.
5. Check + 25-volt supply for ripple
a. Remove the VOM leads. Remove the 50 Ω termination
from the Type 1A1 input but leave it connected to the coax
cable.
b. Connect a 1 X probe to the Type 1A1 Channel 1 input.
c.
1 X probe, check that the ripple on the outside shell of C298
does not exceed 10 millivolts. Check only for 60- or 120-
cycle ripple; disregard the various transients noted.
d.
check that the ripple does not exceed 10 millivolts.
e. Return the variable line voltage source to 115 volts
and remove the 1 X probe from C298 and from the Type 1A1
Channel 1 input.
Maintenance and Calibration — Type 114
R125 PER OD CAL
R290
et the test oscilloscope for line triggering. Using the
et the variable line voltage for 94 . 5 volts and again
100 nsec width
adjust C195F
± 0.5 v.
4-5
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