TM 1-6625-476-30
7-9
7-6. TEST DESCRIPTION. (CONT)
(2)
BORESIGHT AND SCALING TEST. Measures the image boresight and adjusts the rotation
and boresight, if the parameters are out of tolerance. Apply horizontal and vertical scaling voltages to the
offset circuits of the camera to allow the measurement of camera offset.
i.
SIGNAL UNIFORMITY TESTS. Check the output video for absence of shading, blemishes, and
after-images.
(1)
SHADING TEST. Measure any shading in the output video produced by electronic circuits.
(2)
BLEMISH TEST. Check certain zones on the face of the vidicon for blemishes of certain size,
amplitude, and color.
7-7. PRETESTING DATA.
Awareness of the following information will help you to successfully test the UUT, and may prevent
unnecessary termination of the test.
CAUTION
To prevent possible burning of UUT vidicon tube, perform all image
evaluations and UUT adjustments quickly.
a. Possible Vidicon Burns. The image of the optical signal generator test chart may become
permanently burned into the UUT vidicon tube if viewed for long periods of time.
CAUTION
Operation of visual multiplexer or visual relay/multiplexer assemblies in the
underscan mode beyond 2 minutes may produce permanent underscan
raster burn on the vidicon tube.
b. Automatic Return to Full Scan Mode. Prolonged operation of the visual multiplexer assembly and the
visual relay/multiplexer assembly in the underscan mode may produce a permanent underscan raster
burn on the vidicon tube. Therefore, the program will automatically return to full scan operation for 2
minutes if operation in the underscan mode exceeds 2 minutes.
c. UUT Warmup. Since some UUT parameters are temperature dependent, accurate evaluation
requires that a sufficient warmup period be allowed prior to measurement. The UUT test program
automatically provides the required warmup period in the ALL TEST and MENU SELECTION modes. A
message on the VDT will inform you that a warmup period is in progress.
7-8. FINAL ACCEPTANCE.
When the UUT has been repaired, repeat the UUT test. If an ALL TESTS GO prompt is received at the
end of the test, the UUT is considered to be fully operational.
