Service manual

STP 11-25R13-SM-TG
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Performance Steps
(1) Locate the crosshatch pattern intersections in the small circles projected on the screen.
The tolerance is +/-1 percent of picture height within the central area bounded by a circle
whose diameter equals the picture height. Outside the central area, the tolerance is +/-2
percent of picture height.
(2) Adjust H and V SIZE for the best size that places the intersections of the crosshatch
pattern within the tolerances described in step (1) above.
(3) Remove the linearity graticule and light source.
(4) Turn ON the R and B SCREEN switches.
e. Adjust convergence.
(1) Display a dot signal from the VTSG.
(2) Adjust H and V STATIC to converge the center area of the display (static convergence).
(3) Adjust H PARABOLA and TILT for dynamic convergence near the edges of the display.
(4) If necessary, slightly readjust H and V STATIC while adjusting H PARABOLA and TILT.
Optimize the adjustments between FULL SIZE scan and UNDERSCAN.
NOTE: H TILT converges the left side opposite to the right side. H PARABOLA converges the left and
right sides opposite to the center.
f. Adjust screen bias with color bars from the VTSG.
(1) Set the OPERATE AFC FAST-OPERATE-SETUP switch to SETUP and the MODE switch
to MONOCHROME.
(2) Check that the back bar at the right side of the display appears dark gray due to the
increased display brightness in this mode of operation. If the black bar is not dark gray
(black, light gray, or a color shade), go to step (5) below.
(3) Set the OPERATE AFC FAST-OPERATE-SETUP switch to OPERATE.
(4) If the display shows the proper shades of gray, go to step h.
(5) Turn OFF the G and B SCREEN switches. Set the OPERATE AFC FAST-OPERATE-
SETUP switch to SETUP and the MODE switch to AUTO.
(6) Adjust R SCREEN BIAS so that the black bar areas just become black. Adjust CW until
the black areas become dimly red. Then turn the adjustment slowly CCW until the dimly
red areas become barely visible.
(7) Turn OFF the R SCREEN switch and turn ON the G SCREEN switch.
(8) Adjust G SCREEN BIAS so that the black bar areas just become black. Adjust until a faint
yellow line is visible.
(9) Turn OFF the G SCREEN switch and turn ON the B SCREEN switch.
(10) Adjust B SCREEN BIAS so that the black bar areas just become black. Adjust until a faint
white line is visible.
g. Adjust final settings for SCREEN BIAS.
(1) Set the OPERATE AFC FAST-OPERATE-SETUP switch to OPERATE. Turn ON the R,
G, and B SCREEN switches.
(2) On the VTSG, select a white flat field (20 IRE for NTSC or 10 percent for 50 Hz and 60 Hz
PAL models).
NOTE: If the VTSG does not have this capability, select a 100 IRE or 100 percent white flat field. Use
the receiver/monitor variable CONTRAST control to reduce the display to a very low light level equivalent
to approximately 20 IRE to 10 percent white flat field.
(3) Hold the reference light-source, placing the light pipe against the faceplate at the center of
the screen. Adjust the brightness of the light-source reference field to match the
brightness of the test spot.
NOTE: Ensure that the ambient lighting in the room is sufficiently low and the proper color, to not affect
the light-source reference field. Turn OFF the room lights or use a black cloth as a cover to block out
extraneous room lighting to accomplish this.
(4) Check low light color balance (the color of the test spot , with all beams on, matches the
color of the light-source reference field).
(5) Adjust the appropriate SCREEN BIAS adjustments to match the color of the test spot and
the light-source reference field. Slightly readjust the reference field brightness (if
necessary) to match the brightness of the test spot.