TM 11-5826-225-35
Figure 2-19. Control unit test setup.
defective or the dial and synchro are out of alignment.
a. Tuning Meter Test. Set test set RECEIVER-
c. Resistance and Continuity Tests.
CONTROL switch to CONTROL and CONTROL
(1) Set test set DC POWER switch to OFF. Con-
TEST switch to position 1. Set DC POWER switch to
nect test leads of multimeter to the two panel connec-
ON. The tuning meter on the control unit under test
tors on the test set marked CONTROL TEST and set
should indicate half scale and the panel and dials should
multimeter to the RX 1 ohms range.
be illuminated. If the tuning meter indicates otherwise
(2) Set test set CONTROL TEST switch to posi-
or is inoperative, tuning meter M301 (fig. 2-20) is
tion 1. The multimeter should indicate zero ohms.
defective.
b. Tuning Synchro Test.
(3) Set multimeter to the RX10 range. Turn con-
trol unit LOOP control to the first position left and
(1) Set control unit function switch to the ADF
right. The multimeter should indicate 4,700 ohms for
mode.
(2) Set control unit range switch to the 850-1750
both low speed positions of the LOOP control.
(4) If the multimeter indications are not as
position, Tune control unit to 850 kc. The test set
specified in (2) and (3) above, LOOP switch S303 is
BEARING INDICATOR pointer should indicate 343
defective.
1 degree.
(3) Tune control unit until the FREQUENCY
(5) Set test set CONTROL TEST switch to posi-
tion 2, With the BFO-OFF switch in OFF position, the
dial hairline bisects the small zero between 1,400 and
1,500 kc, The test set BEARING INDICATOR should
multimeter should indicate infinity. Set BFO-OFF
indicate 239 1 degree,
switch to BFO. An ohmmeter reading other than zero
(4) Tune control unit to 1700 kc. The BEARING
indicates that BFO-OFF switch S301 is defective,
INDICATOR should indicate 203 2 degrees.
(6) Set CONTROL TEST switch
t o position 3. S e t control unit function
(5) If the BEARING INDICATOR pointer in-
switch to
ADF.
The
m u l t i meter
dication does agree with the normal indications ob-
tained in the above tests, either tuning synchro B301 is
2-36
Change 4
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