TM 11-6720-242-35
vdc to pins 2a and 2A (ground).
(1) Connect a jumper wire between pins 2a and 1Z.
(4) Connect the voltmeter across pins 2E and 2A and
(2) Connect the oscilloscope and the electronic counter
check for a reading that is between 0.535 and 0.552
to pins 2M and 2A (ground).
vdc.
(3) Adjust the power supply for an input of +4.60.01
(5) Connect the voltmeter to pins 1E and 2A and check
vdc.
The time between pulses appearing on the
for the same reading.
oscilloscope must be 2 0.02 seconds. If this is not the
(6) Remove the +22 2 vdc from pins 1a and 2C
case, keep replacing the value of R35 until the timing is
(ground).
as specified.
(7) Connect the voltmeter to pins 1E and 2A and check
(4)
Adjust the power supply for an input of
for a reading of between 0.535 and 0.552 vdc.
+2.017+0.05vdc. The time between pulses appearing
(8) Remove the jumper between pins 2a and 1Y. With
on the oscilloscope shall be 4.26+0.05 seconds. If this
the voltmeter still connected across pins 1E and 2A, the
is not the case, keep replacing R34 until the timing is as
reading shall be between +0.1528 and +0.1582 vdc.
specified
(9) Remove the jumper from pins 2a and 1Z.
(5) If R34 was changed in step (4), step (3) must be
e. Checking and Selecting R15. The proper value of
repeated. If R35 was changed in step (3), step (4) must
be repeated.
resistor R15 is selected by test from among the
(6) Adjust the power supply for an input of +7.00
following listed values. They have a tolerance of + 1
0.01vdc.
percent and are rated at 1/8 watt.
(7) Check that the waveform on the oscilloscope is as
97.6
107
shown on figure 4-9.
100
110
(8) Connect +22 2vdc to pin la. Connect the
102
113
oscilloscope to pins 2X and 2A (ground) and check that
105
the waveform is as shown in figure 410.
(1) Connect +22 2 vdc across pins la and 2C (ground).
(9) If there is difficulty in meeting the conditions
(2) Adjust the power supply for an input of +4.0 0.1
stipulated in steps (3) through (8), replace VR5. If type
vdc across pins 2a and 2A.
1N752A is presently used, replace it with 1N751A or
(3) Connect the voltmeter across pins 1E and 2A and
vice versa.
check for a reading of +0.800 0.016 vdc. Connect the
(10) Remove the jumper wire from between 2a and 1Z.
voltmeter across pins 2E and 2A and check again for
c. Checking and Selecting R10. This test is performed
the same reading.
(4) If a reading of +0.800 0.016 vdc is not obtained in
with the values of R22, R34, and R35 as selected above
step (3), substitute R15 with resistors from the above
still in the unit and without the jumper between pins 2A
list. With each substitution, repeat the test until the
and 1Z. Resistor R10 has a tolerance of 1 percent, is
specified voltage is obtained.
rated at 1/8 watt and is selected from among the
(5) Disconnect +22 2 vdc across pins 1a and 2C.
following:
(6) Connect the voltmeter across pins 1E and 2A and
536 K
check for a reading of +0.800+0.016 vdc. Connect the
549 K
voltmeter across pins 2E and 2A and check for the
562 K
same voltage.
f. Checking IMC Signal.
(1) Adjust the power supply for an input of +7.818+0.05
vdc to pins 2a and 2A (ground).
(1) Connect a jumper wire between 2a and 1Z.
(2) Connect the oscilloscope and the electronic counter
(2) Adjust the power supply for an input of +12 1 vdc
to pins 2M and 2A and check for a time of 4.0 0.06
across pins 2a and 2A (ground).
seconds between pulses. If this is not the case, replace
(3) Apply +22 2 vdc between pins la and 2iC (ground).
R10 until the timing is as specified.
(4) Connect the voltmeter across pins ID and 2C and
d. Testing the V/H Scaling Circuits.
check for a reading of +11 2 vdc.
(5) Remove the +22 vdc from pins la and 2C The
(1) Connect a jumper wire between pins 2a and 1Y,
voltmeter reading at pin ID should now be zero volts
another jumper between pins 2a and 1Z.
(open circuit).
(2) Connect +22 2vdc between la and 2C (ground).
(3) Adjust the power supply for an input of +12.0+.003
4-13
