Service manual

STP 11-25R13-SM-TG
3 - 68
PERFORM TELEVISION SYSTEM TIMING
113-575-8018
Conditions: In a tactical or garrison environment, given a video switcher, source inputs (such as a
satellite, video cameras, VTRs, still store, paint box, and character generator), coaxial cables with
connectors, delay lines, master synchronizing (sync) reference generator, VTSG, VDAs, two color TV
monitors, WFM, vectorscope, alignment tool, prerecorded color bars test tape, DA Form 2407,
manufacturers' manuals, and one assistant.
Standards: The standards are met when all horizontal sync pulse leading edges and subcarrier zero
crossings are synchronized with the zero timing point.
Performance Measures Results
1. Turn ON all equipment (switcher, source inputs, WFM, vectorscope, and monitors). P F
2. On the switcher PVW bus, select the external reference input, color black, which is the
zero timing point, the reference for all calculations and measurements.
P F
3. Prepare the WFM for checking H timing. P F
a. Adjust INTENSITY, FOCUS, and SCALE ILLUMINATION for a clear, sharp image. P F
b. Set INT-EXT SYNC to EXT. P F
c. Depress the DC RESTORER button. P F
d. Check INT CAL for 1 V P-P at 140 IRE; adjust VERTICAL GAIN with an alignment
tool if necessary.
P F
e. Select FAST RESPONSE. P F
f. Select 5 usec/DIV, 2H MAG SWEEP, and UNCAL to magnify the time per division
setting as far out as possible.
P F
g. Adjust the H and V position controls to place the 50 percent (middle) amplitude
point of the sync pulse leading edge on one of the H axis graticule marks. Do not
move the zero timing point once set until timing is finished.
P F
4. Prepare the vectorscope for checking subcarrier (SC) phase. P F
a. Adjust INTENSITY and FOCUS for a clear, sharp image. P F
b. Set SYNC to EXT SC. P F
c. Adjust PHASE CONTROL to set the burst vector on the 180-degree reference line
(9 o'clock position), 75 percent/100 percent mark.
P F
d. Adjust UNCAL to expand the burst vector close to the edge of the display circle.
Do not move this reference point once set until phasing is finished.
P F
5. Switch through the input sources on the PVW bus and adjust each source's internal
timing and phasing.
P F
a. Select Black Burst on one bus and the source being timed on the other bus. Wipe
between the two buses and observe the leading edge of the H sync pulse for
shifting on the WFM.
P F
b. Advise your assistant to adjust the H SYNC on the source equipment being timed
with an alignment tool or adjust knob until aligning the H SYNC pulse leading edge
on the same graticule mark as the zero timing point, +/- 0.2 usec, on the WFM.
P F
c. Direct your assistant to adjust SC PHASE on the source equipment being phased
with an alignment tool or adjust knob until aligning the burst phase with the zero
timing point, +/- 2 degrees, on the vectorscope.
P F