Service manual

STP 11-25R13-SM-TG
3 - 78
REPAIR A TELEVISION PRODUCTION SWITCHER
113-575-0054
Conditions: In a tactical or garrison environment, given a TV production switcher reported inoperable or
malfunctioning on a DA Form 207, two color TV monitors, WFM, vectorscope, dual-trace oscilloscope with
10X test probes, multimeter with test leads, VTSG, electronic equipment tool kit, soldering tool kit (light to
medium duty), bench stock, system block diagrams, manufacturers' manuals, and DA Pam 738-750. At a
minimum, the switcher's inputs should include VTRs and cameras.
Standards: The standards are met when the switcher is restored to optimum operating condition with all
lights lit and all combinations of crosspoint buses transitioning the input signals between Preview and
Program.
Performance Measures Results
1. Review DA Form 2407. P F
2. Sectionalize the trouble to a defective stage. P F
a. Visually inspect for physical damage, missing controls, broken switches, cracked
components, loose or disconnected connectors, and other discrepancies.
P F
b. Operations check the switcher to verify that the deficiency or symptom exists and
to what extent.
P F
(1) Turn ON the switcher. P F
(2) Depress each pushbutton to ensure each lamp illuminates; replace lamp if
necessary.
P F
(3) Select Black on all buses and turn OFF the Mix Effects (ME) generators. P F
(4) Position the PGM and PVW fader bar in the PGM position. P F
(5) Check each crosspoint in the PGM bus while observing the output on the
PGM monitor, WFM, and vectorscope.
P F
(6) Check each crosspoint in the PVW bus while observing the output on the
PVW monitor, WFM, and vectorscope.
P F
(7) Check each crosspoint in the ME buses while observing the PGM and PVW
monitors, WFM, and vectorscope.
P F
(8) Check the Special Effect banks by testing ME-1, ME-2, and ME-3 separately
in PGM and PVW.
P F
( a) Select a video source (except Black or Background) on A bus and a
different source on B bus.
P F
( b) Hard wipe from A to B bus. P F
( c) Dissolve from B to A bus. P F
(9) Check the Pattern Effects generator by testing ME-1, ME-2, and ME-3
separately in PGM and PVW.
P F
( a) Select a video source (except Black or Background) on A bus and a
different source on B bus.
P F
( b) Pattern wipe from A to B bus for each effects pattern. P F
(10) Check CHROMA key. P F
(11) Check COLOR BACKGROUND for adjustable hue and saturation. P F
(12) Depress the FADE-TO-BLACK pushbutton. P F
3. Localize the trouble to a specific circuit by analyzing overall block diagrams and by
performing functional tests on suspected circuits.
P F
a. Check internal switcher timing. P F
(1) When vertical wiping from bottom to top, observe the color bars on the
monitor for any difference in hue between the two sources on the split
screen.
P F
(2) Any difference in hue indicates improperly timed cable length in the
switcher's internal paths.
P F