Service manual

STP 11-25R13-SM-TG
3 - 81
Subject Area 7: INSPECTION
INSPECT A VIDEO TEST SIGNAL GENERATOR (VTSG)
113-575-5018
Conditions: In a tactical or garrison environment, given a VTSG, color TV monitor, WFM, vectorscope,
dual-trace oscilloscope with 10X test probes, test cable (75-ohm BNC-to-BNC), manufacturers' manuals,
DA Form 2404, DA Form 2407, and DA Pam 738-750.
Standards: The standards are met when the VTSG is inspected and signals meet NTSC standards.
Performance Measures Results
1. Review DA Form 2407 P F
2. Connect and set up the color TV monitor, WFM, and vectorscope; then turn ON power
to all equipment.
P F
3. Check display switches and observe the monitoring equipment for correct signals. P F
a. Depress SMPTE color bars. P F
b. Depress FULL FIELD color bars. P F
c. Depress the /Y REF button. P F
d. Depress the /RED button. P F
e. Depress the /REVERSE button. P F
4. Check the amplitude and phase reference switches. P F
a. Depress FULL FIELD (SETUP 7.5 percent/0 percent and WHITE REF 100 IRE/75
percent) and observe the following:
P F
(1) On the video monitor, the luminance level of the white bar becomes brighter. P F
(2) On the WFM, SETUP is inserted at 7.5 IRE of the color bar display and the
white reference level adjusts from 75 IRE to 100 IRE.
P F
b. Depress the PHASE (R-Y) ALT/90-degree button and observe the following: P F
(1) On the video monitor, a loss of R-Y Chrominance lock is displayed. P F
(2) On the vectorscope, an R-Y Chrominance phase shift is displayed. P F
5. Check signal modification switches. P F
a. Depress the Y button and observe that the video monitor and WFM displays have
lost the luminance portion of the composite signal. Release the Y button.
P F
b. Depress the B-Y button and observe the following: P F
(1) On the video monitor, a loss of blue, green, magenta, and yellow Chroma is
displayed.
P F
(2) On the vectorscope, subcarrier with vertical vectors on a 90-degree axis is
displayed.
P F
(3) On the WFM, a loss of B-Y Chrominance is displayed. Release the B-Y
button.
P F
c. Depress the R-Y button and observe the following: P F
(1) On the video monitor, a loss of red, green, magenta, and cyan Chroma is
displayed.
P F
(2) On the vectorscope, subcarrier with horizontal vectors on a 180-degree axis
is displayed.
P F
(3) On the WFM, a loss of R-Y Chrominance is displayed. Release the R-Y
button.
P F
d. Depress the BURST button and observe the following: P F
(1) On the video monitor, a loss of Chroma is displayed. P F
(2) On the vectorscope, the display free runs. Release the BURST button. P F
e. Depress the SYNC button and observe the following: P F