TB 55-4920-428-35
SECTION IV
CALIBRATION PROCESS
NOTE
Unless otherwise specified, verify the result of each test and, whenever
the test requirement is not met, take corrective action before continuing
with the calibration. Adjustments required to calibrate TI are included in
this procedure. Additional maintenance information is contained in TM
55-4920-428-13 for this TI.
8. Nullmeters (SAS1) and (SAS2). (Not Modified Circuit).
a. Performance Check.
(1) Disconnect TI nullmeter (SAS1) leads from back of indicator.
(2) Connect test equipment as shown in figure 1 with decade resistor (A6) controls set to 200K
ohms.
(3) Adjust DC power supply (A2) for +50 uadc on TI nullmeter (SAS1). Digital multimeter (A) will
indicate between 45 and 55 mvdc.
(4) Adjust DC power supply for +25 uadc on TI nullmeter (SAS1). Digital multimeter will indicate
between 20 and 30 mvdc.
(5) Adjust DC power supply for Null position on TI nullmeter (SAS1). Digital multimeter will in-
dicate ZERO.
(6) Repeat technique (3) thru (5) above after changing polarity of test leads from back of TI
nullmeter (SAS1). Digital multimeter will indicate negative readings in step (3) and (4) above.
(7) Connect TI nullmeter (SAS1) leads to back of indicator.
(8) Disconnect TI nullmeter (SAS2) leads from back of indicator and connect test equipment as shown
in figure 1.
(9) Repeat technique (3) thru (6) above for the TI nullmeter (SAS2). Digital multimeter will indicate
within the limits specified for each check.
(10) Connect TI nullmeter (SAS2) leads to back of indicator and disconnect test equipment.
b. Adjustments. No adjustments can be made.
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