2548H INSTRUCTION MANUAL
56-101-00420 Rev. C
Ch. 3
Nov
/
07
/
14
Page 22 of 33
B. Capacitance Test Procedure
Note: Refer to the appropriate maintenance manuals for individual tank unit locations
and capacitance values by part numbers.
(1) Set the TANK CAP pF thumbwheels to the value of the Tank-Unit-Under-Test. (If
configuration is in accordance with Figure 12, also rotate the adapter’s PROBE
SELECTOR switch to the position of the Tank-Unit-Under-Test.)
(2) Press the PRESS TO MEASURE pushbutton.
(3) Verify that the Test Set’s meter pointer is null within tolerance of the Tank-Unit-
Under-Test.
Note: Failure to null within tolerance means there is a defective tank unit, bad
connection or a poor pin contact.
Make the necessary repairs and repeat
the test procedure.
(4) Release the PRESS TO MEASURE pushbutton.
(5) If there are additional tank unit electrical connectors or bulkhead connectors in the
system configuration, repeat the test procedure for each connector.
(6) If not, set the Test Set’s ON/OFF switch to OFF.
Note: A SYSTEM CAPACITANCE TEST (refer to section 5.) should be done after
an individual capacitance test and before continuing to the AMPLIFIER
TEST/CALIBRATION.
8. AMPLIFIER TEST/CALIBRATION
The amplifier may be bench tested and calibrated with the appropriate independent cable, or
with an adapter for the adapter cable used for aircraft test/calibration. The tank unit circuits are
not used in the amplifier test and are “electrically” removed from the system.
Some adapter cables have leads that are wired through and are present at each end of the
cable. In those cases, the circuits must be disconnected elsewhere in the system.
