TM 11-6625-3025-14/ET426-AA-MMA-010/E154 VII210/T.O. 33A1-8-902-1-1
between the GRAY SCALE and V STRIPE functions. If the control is too high, the black step of the gray scale waveform
will be clipped and reduced in height. If it is too low, the V stripe black level will be below the gray scale black level.
8. Return the VIDEO LEVEL control to 0 (maximum counterclockwise). Set the oscilloscope channel 1 input
sensitivity at 0.l1 per division. Adjust control (R43 on the video card) counterclockwise to obtain desired blanking pedestal
level, nominally 0.055v.
9.
Set oscilloscope channel 1 input amplitude sensitivity at 0.5v per division. 6
10 Adjust the sync level control R11 of the video card to set amplitude of the sync portion of the signal at 0.4v
peak-to-peak +0.04v or other desired amplitude.
11. Set front panel VIDEO LEVEL control at 10. Adjust the white level using control.R32 of the gray scale control
card (figure 6-9) for 1.0v or other desired limit of video portion of the composite video signal (including 0.055v blanking
level). The composite video signal should then be 1.4v (1.0v video with 0.055v and blanking pedestal +0.4v sync).
12. If the levels are to be adjusted for less than maximum values, reduce the amplitudes obtained in steps 8
through 11 as required.
13. To check source impedance, remove the termination at the coax tee on oscilloscope channel 1 input .The
signal level should double from those set in steps 8 through 12. Replace the termination.
14. This completes signal level adjustments.
6-39.
Flat Field Adjustments. The circuit cards involved in the flat field pattern (see figure FO-21) include:
Video ........................................................................................................................
Position 5C
Pulse Input ...............................................................................................................
Position 2C
Polarity ....................................................................................................................
Position 3C
Gray Scale Control ..................................................................................................
Position 5B
1.
Set oscilloscope sweep rate to 2 msec per division.
2.
connect the oscilloscope external sync input to the V drive source.
3. Connect the video coax cable to the video G output connector and oscilloscope channel 1 input.
Set
oscilloscope channel 1 input amplitude sensitivity at 0.5v per division.
6-34
