TM 11-5840-281-35/1
(3) Fixed coil amplifier installed with test
(14) On fixed coil amplifier, disconnect vtvm
adapter (card extender from cover of Radar Receiver-
COMMON lead from HORIZ FB NO. 1 and connect it to
Transmitter RT-818/TPN-18) A10300 in applicable
GRD testpoint TP1801 on 12v voltage regulator.
Control-Indicator C-6988/TPN-18 and vtvm connected as
(15) Adjust HORIZ CURRENT ADJ control
shown in figure 3-37.
R2128 until vtvm indicates -0.35 volt.
c. Procedure.
(16) On master Control-Indicator C-6988/
(1) On master Control-Indicator C-6988/
TPN-18, place POWER circuit breaker to OFF.
TPN-18 and Pulse Generator O-1333/TPN-18 place
(17) Remove test adapter (card extender)
POWER circuit breaker to ON, SCAN MODE switch to
and fixed coil amplifier from Control-Indicator C-
SEARCH, and NORM-OFF-SET switch S601 to
6988/TPN-18. Reinstall fixed coil amplifier Control-
OFFSET.
Indicator C-6988/TPN-18. Return card extender to
(2) On fixed coil amplifier, place HORIZ
Receiver Transmitter RT-818/ TPN-18 cover.
CURRENT ADJ R2128, VERT CURRENT ADJ R2123,
(18) On master Control-Indicator C-6988/
and VERT BAL R2109 controls to midposition.
TPN-18, place POWER circuit breaker to ON, if
(3) On vtvm, place RANGE switch to S0V
applicable.
and SELECTOR switch to (-) or (+) as applicable.
Observe meter to determine correct polarity for placing
NOTE
vtvm SELECTOR switch.
(4) On front of applicable Control-Indicator
Do not replace rear cover on Control Indicators
C-6988/TPN-18, adjust PPI CENTERING-VERT knob
C-6988/TPN-18
until
alignments
and
control until vtvm indicates 0-volt.
adjustments are completed.
(5) On fixed coil amplifier, disconnect vtvm
leads from pin 2 and pin 7 of connector.
3-39. Deflection Yoke Assembly Positioning
(6) On vtvm, place RANGE switch to 10V
and SELECTOR switch to (-) or (+) as applicable.
Observe meter to determine correct polarity for placing
a. Test Equipment Required. None required.
SELECTOR switch.
b. Equipment Conditions. Primary ac power re-
(7) On fixed coil amplifier, connect vtvm DC
moved from circuits in Control-Indicator C-6988/TPN-18
lead to VERT FB NO. 1 testpoint TP2101.
under alignment. (Refer to note in c below.)
Connect vtvm COMMON lead to VERT FB NO. 2
c. Procedures
testpoint TP2102.
(8) Adjust VERT BAL control R2109 until
NOTE
vtvm indicates 0-volt.
(9) On vtvm, place RANGE switch to 10V
Adjustment of the deflection yoke assembly is not
and SELECTOR switch to (-).
necessary unless the cathode ray tube or deflection
(10) On fixed coil amplifier, disconnect vtvm
yoke assembly has been replaced. Primacy ac
COMMON lead from VERT FB NO. 2 testpoint TP2102
power may or may not be applied through POWER
and connect it to GRD testpoint TP1801 on 12v voltage
circuit breaker CB601 on master Control-Indicator
regulator.
C-6988/TPN-18 to both Control-Indicators C-
(11) Adjust VERT CURRENT ADJ control
6988/TPN-18, depending on interconnecting cable
R2123 until vtvm indicates -0.35 volt. Place RANGE
connections
between
Control-Indicators
C-
switch on vtvm to lower ranges as indication approaches
6988/TPN-18. Ensure that primary ac power is
-0.35 volt for greater accuracy.
turned off on applicable Control-Indicators C-
(12) On fixed coil amplifier, disconnect vtvm
6988/TPN-18 before positioning deflection yoke
leads. Place RANGE switch on vtvm to 10V.
assembly.
Connect vtvm COMMON lead to HORIZ FB NO.
1 testpoint TP2103 and connect vtvm DC lead to HORIZ
(1) Remove top access cover from top of
FB NO. 2 testpoint TP2104.
applicable Control-Indicator C-6988/TPN-18 case by
(13) On front of Control-Indicator C-6988/
removing
10
screws
from
access
cover.
TPN-18, adjust PPI CENTERING-HORIZ knob control
R611 until vtvm indicates 0-volt.
3-48
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