TM 11-6625-3025-14/ET426-AA-MMA-010/E154 VII210/T.O. 33A1-8-902-1-1
Section V. Performance Verification and Adjustments
6-33. Introduction. The test pattern generator operates automatically, developing an analog television signal through
digital techniques. Therefore, no extensive adjustment procedure is required. The procedure outlined in this section
should be followed to ascertain that the instrument is functioning properly and that pattern and pulse values are proper for
the scan rate in use.
This procedure is dual purpose. It is used to verify performance of the instrument to specification, a procedure
which can be accomplished without removal of panels and change of internal controls. If adjustment is desired, as
indicated by variations observed during performance verification, the top panel must be removed for access to controls.
6-34. Test Equipment. The performance verifications and adjustment procedures make use of the test equipment
specified in the Maintenance Allocation chart in Appendix B.
6-35. Voltage Levels. Power supply levels must be verified prior to performing adjustment procedures (+12v, +5v, and
-5v) to establish proper reference levels for all operations. Test points (TP1-TP4) are provided on the power regulator
card shown in figure 6-3 to check the voltage levels. Control (R1) is provided at the right side of the power regulator card
to adjust the +5v supply. Others are not adjustable.
6-36. Sync Generator Section Adjustment Procedure.
Vertical timing is controlled by the counter circuits, and
therefore is automatically locked to the horizontal rate.
NOTE
All outputs must be terminated in 75 ohms.
1. Refer to table 6-3 for proper timing relationships for the scan rate in use. See figures 4-1 and 4-4 for
conformance to typical waveforms.
2. Sync the oscilloscope from the leading edge (-) of H drive. Set oscilloscope sweep rate as desired for
inspection of timing as described in each step of adjustment.
3. Observe the H drive waveform at the rear panel. Pulses should be 8v, pk-pk (unterminated) negative going
with edges spaced as shown in table 6-3. Adjust the pulse width to the proper value by use of the control (R1) at the left
edge of the drive blanking card (see figure 6-4).
4. Observe the blanking output, with oscilloscope sync remaining at H drive. Observe amplitude, polarity and
leading edge spacing shown in table 6-3. Adjust H blanking pulse width by use of the control (R2) second from the left
edge of the drive blanking card.
6-21
