Service manual

STP 11-25R13-SM-TG
3 - 70
CONDUCT QUALITY CONTROL (QC) OF VIDEO AND AUDIO SIGNALS
113-575-5017
Conditions: In a tactical or garrison environment, given video and audio sources and program outputs,
WFM, vectorscope, video audio test signal generator(s), test meters, audio amplifier, speaker(s), color TV
monitor(s), patch panels, switching equipment, multimeter with test leads, 75-ohm terminators, 75-ohm
video cables with BNC connectors attached, audio wires, alignment tool, manufacturers' manuals, signal
check log sheet, DA Pam 738-750, and DA Form 2407.
Standards: The standards are met when all signals are free of distortion and noise and displayed within
NTSC standards.
Performance Measures Results
1. Turn ON and set up the WFM. P F
a. Set VERTICAL INPUT to A DC. P F
b. Set VOLTS FULL SCALE to 1. P F
c. Depress RESPONSE to FLAT for display of the entire signal. P F
d. Horizontally and vertically center the trace on the 0 IRE graticule line. P F
e. Adjust INTENSITY, FOCUS, and SCALE ILLUMINATION for sharp, comfortable
viewing.
P F
f. Depress DC RESTORER to ON, which eliminates bouncing or floating and
stabilizes the display from variations in average picture level (APL).
P F
g. Verify VERTICAL GAIN and INTERNAL CALIBRATION by depressing the CAL
button and adjusting the VERTICAL position to place the trace on the 100 IRE and
-40 IRE lines. If the signal is not 1 V P-P at 140 IRE, adjust VERTICAL GAIN with
an alignment tool (small insulated screwdriver).
P F
2. Turn ON and set up the vectorscope. P F
a. Adjust INTENSITY for medium illumination. P F
b. Adjust FOCUS for a sharp trace. P F
c. Adjust SCALE ILLUMINATION for lighting the graticule area. P F
d. Set Astigmatism (ASTG) by depressing the VECTOR button and adjusting
FOCUS and ASTG for the smallest round spot possible in the center of the
graticule.
P F
3. Connect, patch, or select (on the switching equipment) the test signal generator(s) to
the monitoring equipment using the appropriate video and audio cables and
connectors.
P F
4. Turn ON the test signal generator(s) and verify signals on the monitoring equipment, as
well as the operation of the test-monitoring equipment.
P F
a. On the WFM: 140 IRE at 1 V P-P, composite EIA color bars. White level is at 100
IRE and sync is at -40 IRE.
P F
b. On the vectorscope: 75 percent burst amplitude with all vectors within their
respective vector boxes.
P F
c. On the color TV monitor: color bar presentation. P F
d. On the test meters: 1 kHz tone at +4 dBm. P F
e. On the speaker(s): an audible tone. P F
5. Remove test cables or patches. P F
6. Select the desired signal to check on the switching equipment and annotate test
readings on the signal check log sheet.
P F
7. The following readings are acceptable. P F
a. Video or White level at 100 IRE on the WFM. P F